3g overview

Part I3G Overview

1Company Confidential

What’s New in WCDMA?Characteristic to WCDMA• RAKE receiver takes advantage of multipath propagation• Fast power control keeps system stable by using minimum power necessary for

links• Soft handover ensures smooth handovers


Multiservice Environment• Data speed

– In RAN1 bit rate varies from 8 kbps up to 384 kbps– Variable bit rate also available– Bit rate gradually grows up to 2 Mbps

• Service delivery type– Real-time (RT) & non real-time (NRT)

• Quality classes for user to choose– Different error rates and delays

• Traffic asymmetric in uplink & downlink• Common channel data traffic (FACH)• Inter-system handovers

Air Interface• Capacity and

coverage coupled -“cell breathing”

• Neighbor cells coupled via interference

• Soft handover• Fast power control• Interference limited

system (e.g. GSM frequency limited)


UMTS network architecture

BSS

BSC

RNS

RNC

CN

Node B Node B

A IuPS

Iur

Iubis

USIM

ME

MS

Cu

Uu

MSCSGSN

Gs

GGSNGMSC

GnHLR

Gr

GcC

D

E

AuCH

EIR

F Gf

GiPSTN

IuCSGb

VLRB

Gp

VLRG

BTSBTS

Um

RNC

Abis

SIM

SIM-ME i/f or

MSCB

PSTNPSTN

cell

Ref. 3GPP TS23.002

Microsoft Word Document

3G Spectrum Allocation


IMT2000 Frequency Allocation for UMTS

1900 1920 1980 2010 2025 2110 2170 2200

MSSUL

TDDUL/DL

TDDUL/DL

FDDUL

MSSDL

FDDDL MHz


FDL

FDL/UL

FUL

FDD Mode TDD Mode

3G Terms• IMT 2000

– Third generation mobile systems as defined by ITU– Global recommendation

• 3GPP– 3rd Generation Partnership Project (Forum for a WCDMA standardization)– Involved: ETSI (Europe), ARIB (Japan), TTA (Korea), T1P1 (USA), TTC (Japan)

and CWTS (China)• UMTS

– Third generation telecommunication system, that is subject to specifications produced by 3GPP

• WCDMA– Air Interface technology adapted for UMTS Terrestrial Radio Access (UTRA)

• UTRA-FDD– WCDMA in 3GPP, FDD mode

• UTRA-TDD– WCDMA in 3GPP, TDD mode

• CDMA2000– Air Interface technology proposal from TR45.5 (USA) on evolution of IS-95

(CDMA)


UMTS System Characteristics• W-CDMA : 5 MHz• Carrier Spacing : multiples of 200 kHz• W-CDMA spreading rate = 3.84 Mchip/s• Chip Rate = 3.84 MHz• Raised cosine filtering with roll-off 0.22• Information bit rate: between 8 kbit/s and 2 Mbit/s (currently up to 384 Kbit/s)• Spreading Factor (SF): 4 -256• Multiple Access Scheme : Wideband DS-CDMA• Duplex Scheme : FDD and TDD modes• Carrier Spacing : 4.4 – 5.4 MHz• 10 ms frame with 15 time slots• NodeB synchronization: asynchronous• Highly variable data rates, data rate constant within 10 ms frame• Bandwidth on demand, efficient resource usage• Multiple services with different variable data rates over one physical channel


Key features of WCDMA•Soft handoff: user equipment (UE) and base stations use special rake receivers that allow each UE to simultaneously communicate with multiple base stations. The diversity gain associated with soft handoff is known as the "soft handoff gain factor".

•Multipath reception: the rake receivers also allow the UE to decode multiple signals that have traveled over different physical paths from the base station. For example, one signal may travel directly from the base station to the UE, and another may reflect off a large building and then travel to the UE. This phenomenon, "multipath propagation", also provides a diversity gain. The same effect occurs on the uplink from the UE to the base station.

•Power control: transmissions by the UE must be carefully controlled so that alltransmissions are received with roughly the same power at the base station. If power control is not used, a “near-far” problem, where mobiles close to the base station over-power signals from mobiles farther away, occurs. The base station uses a fast power control system to direct the mobile to power up or power down as its received signal level varies due to changes in the propagation environment. Likewise, on the downlink, transmissions from the base stations are power-controlled to minimize the overall interference throughout the system and to ensure a good received signal by the UE.


Key features of WCDMA

Frequency reuse of 1: every base station in the CDMA system operates on the same frequency for a given carrier, so no frequency planning is required. As every site causes interference to every other site, careful attention must be paid to each site's radio propagation.

Soft capacity: capacity and coverage are intertwined in CDMA, depending on thenumber of users in the system and the amount of interference allowed before access is blocked for new users. By setting the allowed interference threshold lower, coverage will improve at the expense of capacity. By setting the threshold higher, capacity will increase at the expense of coverage. Because of the fundamental link between coverage and capacity, cells with light traffic loads inherently share some of their latent capacity with more highly loaded surrounding cells.


WCDMA Compared to GSM and CDMA IS-95 WCDMA vs. GSMWCDMA has some similarities with GSM technology, however, it is a fundamentally different technique for allowing multiple users to share the same spectrum and as a result it has many differences.



WCDMA Compared to GSM and IS-95 CDMA

Part IIWCDMA Fundamentals


WCDMA = DS-CDMA•WCDMA is a code-division multiple access technology which separates each user’s voice or data information by multiplying the information by pseudo-random bits called "chips". •The pseudo-random bit sequences have a rate of 3.84 Mcps (millions of chips per second), resulting in the narrowband information bits of the user being spread across a much wider bandwidth of approximately 5 MHz.• For this reason, CDMA technology is sometimes referred to as “spread spectrum.”•The user data (signal) is first spread by the channelisation code (based on Hadamard matrix) called Orthogonal Variable Spreading Factor (OVSF) Code.•OVSF code has the property that two different codes from the family are perfectly orthogonal if in phase


TDMA based System



W-CDMA based System

Processing Gain and Spreading


Spreading and Despreading


The spreading sequences must have good correlation properties to facilitate the separation of the wanted signal from all others:•One sharp and dominant peak of the autocorrelation function for zero phase shift•As small as possible values of the autocorrelation function for all out-of-phase shift•As small as possible values of the cross-correlation function for all phase shift

Spreading and Despreading


CDMA Multiple Access Advantages : Multiple Access Features

1. All Users’ Signals overlap in TIME and FREQUENCY2. Correlating the Received Signal despreads ONLY the WANTED SIGNAL


p

f f

S1 p

S1xC1

p

f f

S2 p

S2xC2 f

RECEIVER of USER 1

p S1 = S1 X C1 X C1p

S2 X C2 X C1

f

CDMA Multiple Access Advantages : Interference Rejection

p

f f

S1 p

S1xC1


p

f

I

f

p S1

p

f

I IxC1

Correlation Narrowband Interference Spread the powerOnly a small portion of the interfering signal energy passes the filter and remain as residual interference

CDMA Principles


m1(t)

Tb 2Tb 3Tb

1 -1 1

Tc : Chip Rate of the PN CodeTb : Information rate (voice/data)M1(f)

f1/Tb

C1(f)c1(t)

f1/Tb 1/TcTc 4Tc C1(f)* M1(f)m1(t).c1(t)

f1/Tb 1/Tc

Processing gain (Gp)•Gp = Wc/Wi•Where

–Wc: chip rate–Wi: user data rate

•The more processing gain the system has, the more the power of uncorrelated interfering signals is suppressed in the despreading process•Thus, processing gain can be seen as an improvement factor in the SIR (Signal to Interference Ratio) of the signal after despreading•Example: Voice AMR 12.2 Kbps Gp = 10*log(3840000/12200)= 25 dB•After despreading the signal power has to be typically few dB above the interference and noise: Eb/No = 5dB; therefore the required wideband signal-to-interference ratiois 5dB – Gp = -20 dB.•In other words, the signal power can be 20 dB under the interference and the WCDMA receiver can still detect the signal•Wideband signal-to-interference ratio is also called carrier-to-interference ratio: C/I •Thanks to spreading and desporeading, C/I can be much lower in WCDMA than GSM (C/I = 9-12 dB)

fWi

Wc


Spreading in WCDMAConsists of 2 operations:1. Channelization• Transforms each symbol (data bit) to the number of chips (increases

bandwidth)• Number of chips per symbol = Spreading Factor (SF)2. Scrambling• Scrambling code is applied

Data

Bit Rate

Channelization code (OVSF)

Chip Rate Chip Rate

TX

Scrambling Code


OVSF properties


•In the spreading process, information symbols, which occupy a relatively narrow bandwidth, are multiplied by a high-rate spreading code consisting of chips•The resulting spread signal has a wider bandwidth dependent on the number of chips per symbol•In the de-spreading process, the spreading code is multiplied by the spread signal to recover the original data symbols. The de-spreading process converts the wide bandwidth spread signal back to the original narrower bandwidth of the data symbols•Spreading codes (OVSF) are specially designed to allow the symbols from multiple users to occupy the same spectrum at the same time, while still allowing the original information to be retrieved.•Codes are allocated in RNC•Restrictions: another physical channel may use acertain code in the tree if no other physical channelto be transmitted using the same code tree is usinga code that is on an underlying branch, i.e. using ahigher SF generated from the intended spreading code to be used. Neither can a smaller SF code on the path to the root of the tree be used

SF4

Scrambling code properties• The OVSF codes are effective only when the channels

are perfectly synchronized at symbol level• The loss in cross-correlation, e.g. due to multipaths, is

compensated by the additional scrambling operation• Scrambling codes are used to separate different cells in

the downlink and different terminals in the uplink• They have good correlation properties (interference

averaging) and are always used on top of the spreading codes, thus not affecting the transmission bandwidth


Usage of the codesChannelization Code Scrambling Code

Usage Uplink: separation of physical data (DPDCH) and control channels (DPCCH) for the same terminalDownlink: separation of downlink connections to different users within on cell

Uplink: Separation of terminals

Downlink: Separation of sectors (cells)

Length 4-256 chipsIn downlink also 512 chips

Uplink: 10ms = 38400 chips

Downlink: 10ms = 38400 chips

Number of codes Spreading Factor indicates the number of codes under one scrambling code

Uplink: over 16 millionsDownlink: 512

Code Family Orthogonal Variable Spreading Factor (OVSF)

10ms code: Gold Code66.7µs code: Extended code family

Spreading Yes, indicates bandwidth No, does not affect bandwidth


Receivers• Both NodeB and Terminals use the same type of correlation

receivers• Due to multipath propagation it’s necessary to use multiple

correlation receivers (fingers) in order to recover (combine) the energy from all paths coherently and obtain multipath diversity


Wide Band Channel• Definition:• A channel is defined wide when its bandwidth (Bw) is greater than the

Coherence Bandwidth: Bw >> ∆fc


τπSfc 2

1=∆

Wide Band Channel – Delay SpreadChannel impulse response (power delay profile) and delay spread

Dominant Path

1τ


Wide Band Channel – Narrow/Wide Band System


Microsoft Word Document

WCDMA and GSM in TU3 Channel


Optimal Receiver for WCDMA signal• For a channel with only one signal path optimal receiver is onecorrelator (code de-spreading and integration


Basic unit of Rake Receiver

Optimal Receiver for WCDMA signal• In a multipath environment optimal receiver utilizes several correlators (Rake Fingers) tuned for dominant delays = Rake receiver Adobe Acrobat

Document


Rake Receiver• Rake finger delays tuned based on channel impulse

response estimation• Code Matched Filter, Search Finger• Fingers combined with Maximal Ratio combining• Performance of Rake Receiver depends on the channel

powers delay profile• Max path delay difference vs. chip time amount of

multipath diversity


Rake Receiver - Combining• Combined signal without and with phase estimation and correction (example 6 path channel)


Maximal Ratio Combining of Symbols

Transmitted signal

Received signal (+noise)

Finger n.1

Finger n.2

Finger n.3

Time and phase

adjustment

Combined signal (+ residual noise)

WBTS

UE


Maximal Ratio Combining of SymbolsReceived

symbol+noiseTransmitted

symbol Modified with

channel estimate and relative delay

compensation (for combining)

Combined symbol + residual noise

Finger n.1

Finger n.2

Finger n.3

WBTSUE


WCDMA in TU Channel

time

• High level of multipath diversity


WCDMA in Indoor Channel

Rake Finger RESOLUTION = 0.26µsChip period = 1/3840000 s = 0.26µs


• No multipath diversity.•0.26µs delay can be obtain if the difference in path lengths is at least 78 m (speed of light / chip rate). IS-95 (≈1Mcps) 300m path lengths difference

Part IIIScrambling Code Planning


Scrambling Code Planning


Part IVPhysical Layer


Channel Mapping


In GSM, we distinguish between logical and physical channels. In UMTS there are three different types of channels:

• Logical ChannelsLogical Channels were created to transmit a specific content. There are for instance logical channel to transmit the cell system information, paging information, or user data. Logical channels are offered as data transfer service by the Medium Access Control (MAC) layer to the next higher layer. Consequently, logical channels are in use between the mobile phone and the RNC.

• Transport Channels (TrCH)The MAC layer is using the transport service of the lower, the Physical layer. The MAC layer is responsible to organise the logical channel data on transport channels. This process is called mapping. In this context, the MAC layer is also responsible to determine the used transport format. The transport of logical channel data takes place between the UE and the RNC.

• Physical Channels (PhyCH)The physical layer offers the transport of data to the higher layer. The characteristics of the physical transport have to be described. When we transmit information between the RNC and the UE, the physical medium is changing. Between the RNC and the Node B, where we talk about the interface Iub, the transport of information is physically organised in so-called Frames.Between the Node B and the UE, where we find the WCDMA radio interface Uu, the physical transmission is described by physical channels. A physical channel is defined by the UARFCN and the a spreading code in the FDD mode.

Radio Interface Channel Organisation


Logical Channelscontent is organised in separate channels, e.g.

System information, paging, user data, link management

Transport Channelslogical channel information is organised on transport channel

resources before being physically transmitted

Physical Channels(UARFCN, spreading code)

FramesIub interface


Logical ChannelsThere are two types of logical channels (FDD mode):Control Channels (CCH):• Broadcast Control Channel (BCCH)

System information is made available on this channel. The system information informs the UE about the serving PLMN, the serving cell, neighbourhood lists, measurement parameters, etc. This information permanently broadcasted in the downlink.

• Paging Control Channel (PCCH)Given the BCCH information the UE can determine, at what times it may be paged. Paging is required, when the RNC has no dedicated connection to the UE. PCCH is a downlink channel.

• Common Control Channel (CCCH)Control information is transmitted on this channel. It is in use, when no RRC connection exists between the UE and the network. It is a bi-directional channel, i.e. it exists both uplink and downlink.

• Dedicated Control Channel (DCCH)Dedicated resources were allocated to a UE. These resources require radio link management, and the control information is transmitted both uplink and downlink on DCCHs.

Traffic Channels (TCH):• Dedicated Traffic Channel (DTCH)

User data has to be transferred between the UE and the network. Therefore dedicated resources can be allocated to the UE for the uplink and downlink user data transmission.

• Common Traffic Channel (CTCH)Dedicated user data can be transmitted point-to-multipoint to a group of UEs.


Transport Channels (TrCH)Logical Channels are mapped onto Transport Channels. There are two types of

Transport Channels (FDD mode):

Common Transport Channels:• Broadcast Channel (BCH)

It carries the BCCH information.• Paging Channel (PCH)

It is in use to page a UE in the cell, thus it carries the PCCH information. It is also used to notify UEs about cell system information changes.

• Forward Access Channel (FACH)The FACH is a downlink channel. Control information, but also small amounts of user data can be transmitted on this channel.

• Downlink Shared Channel (DSCH)This channel is used downlink. Dedicated user data and control information for several mobile phones can be transmitted with one DSCH.

• Random Access Channel (RACH)This uplink channel is used by the UE, when it wants to transmit small amounts of data, and when the UE has no RRC connection. It is often used to allocated dedicated signalling resources to the UE to establish a connection or to perform higher layer signalling. It is a contention based channel, i.e. several UE may attempt to access UTRAN simultaneously.

Transport Channels (TrCH)• Common Packet Channel (CPCH)

Similar to the RACH, it is a contention based uplink channel. In contrast to the RACH, it can be used to transmit larger amounts of (bursty) traffic.

Dedicated Transport Channels:• Dedicated Channel (DCH)

Dedicated resources can be allocated both uplink and downlink to a UE. Dedicated resources are exclusively in use for the subscriber.

On the following figures. you can see the mapping of logical channels onto transport channels, as well as the mapping of transport channels onto physical channels.


Physical Channels (PhyCH)Physical Channels are characterised by•UARFCN,•scrambling code,•channelisation code (optional),•start and stop time, and•relative phase (in the uplink only, with relative phase being 0 or π/2)

Transport channels can be mapped to physical channels. But there exist physical channels, which are generated at the Node B only, as can be seen on the next figures.



Channel Mapping DL (Network Point of View)

PCH

BCH

DCH

FACH

DSCH

LogicalChannels

TransportChannels

PhysicalChannels

CTCH

DCCH

CCCH

PCCH

BCCH

DTCH

P-CCPCH

CPICHS-SCHP-SCH

CSICH

CD/CA-ICH

AICH

PDSCH

DPDCH

S-CCPCHPICH

DPCCH

Channel Mapping UL (Network Point of View)PhysicalChannels

LogicalChannels

TransportChannels

DCCH

DCH DPDCHDTCH

CPCH

RACHCCCH

PCPCH

PRACH

DPCCHI branchQ branch


Transport Formats


TB Transport Block TF Transport FormatTBS Transport Block Set TFS Transport Format Set

TFC Transport Format CombinationTFCS Transport Format Combination Set

DCH 2TB TB TB

TBTB

TBTB

TB

TBS

TF

TFS

TFC

TFCS

TTI TTI

TTI

TTI

TTITTI

TB

TBTB

DCH 1

Cell SynchronisationWhen a UE is switched on, it starts to monitor the radio interface to find a suitable cell to camp on. But it has to determine, whether there is a WCDMA cell nearby. If a WCDMA cell is available, the UE has to be synchronised to the downlink transmission of the system information – transmitted on the physical channel P-CCPCH – before it can make a decision, in how far the available cell is suitable to camp on. Initial cell selection is not the only reason, why a UE wants to perform cell synchronisation. This process is also required for cell re-selection and the handover procedure.

Cell synchronisation is achieved with the Synchronisation Channel (SCH). This channel divides up into two sub-channels:

•Primary Synchronisation Channel (P-SCH) (SLOT and CHIP SYNCHRONIZATION)A time slot lasts 2560 chips. The P-SCH only uses the first 10% of a time slot. A Primary Synchronisation Code (PSC) is transmitted the first 256 chips of a time slot. This is the case in every UMTS cell. If the UE detects the PSC, it has performed TS and chip synchronisation. •This is typically done with a single matched filter matched to the primary synchronization code which is common for all cells. The slot timing of the cell can be obtained by decoding peaks in the matched filter output

62Company Confidential(continued on the next text slide)

Synchronisation Channel (SCH)

CP CP

2560 Chips 256 Chips

Cs1 Cs2 Cs15

Slot 1 Slot 14Slot 0

CP CP CP

Cs1

Primary Synchronisation Channel (P-SCH)

Secondary Synchronisation Channel (S-SCH)

Slot 0

10 ms Frame


Cp = Primary Synchronisation CodeCs = Secondary Synchronisation Code

• Secondary Synchronisation Channel (S-SCH) • (FRAME SYNCH and Scrambling Code Group DETECTION)

The S-SCH also uses only the first 10% of a timeslot; Secondary Synchronisation Codes (SSC) are transmitted. There are 16 different SSCs, which are organised in a 10 ms frame (15 timeslots) in such a way, that

• the beginning of a 10 ms frame can be determined, and• 64 different SSC combinations within a 10 ms frame are identified. There is a

total of 512 primary scrambling codes, which are grouped in 64 scrambling code families, each family holding 8 scrambling code members. The 15 SSCsin one 10 ms frame identify the scrambling code family of the cell‘s downlink scrambling code.

• The sequence permits downlink frame synchronization and indicate which of the code grouping the downlink scrambling code belongs to.

• This is done by correlating the received signal with all possible secondary synchronization code sequences and identifying the maximum correlation value. Since the cyclic shifts of the sequences are unique, the code group as well as the frame synchronization is determined

Cell Synchronisation


SSC Allocation for S-SCHscramblingcode group

slot number0 1 2 3 4 5 6 7 8 9 10 11 12 13 14


15

15

group 05group 04

group 62group 63

1 1 2 8 9 10 15 8 10 16 2 7 15 7 161 1 5 16 7 3 14 16 3 10 5 12 14 12 101 2 1 15 5 5 12 16 6 11 2 16 11 12

1 2 3 1 8 6 5 2 5 8 4 4 6 3 71 2 16 6 6 11 5 12 1 15 12 16 11 21 3 4 7 4 1 5 5 3 6 2 8 7 6 8

9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

9 12 10 15 13 14 9 14 15 1

1 11 13 12 16 10

group 00group 01group 02group 03

11

11 11

11 11

11 1111 11

15

15

15

15 15

15

15

15 15

15 15

5

5

I monitor the S-SCH

Common Pilot Channel (CPICH)With the help of the SCH, the UE was capable to perform chip, TS, and frame synchronisation. Even the cell‘s scrambling code group is known to the UE. But in the initial cell selection process, it does not yet know the cell‘s primary scrambling code. There is one primary scrambling code in use over the entire cell, and in neighbouring cells, different scrambling codes are in use. There exists a total of 512 primary scrambling codes. The CPICH is used to transmit in every TS a pre-defined bit sequence with a fixed data rate of 30 kbps, which corresponds to spreading factor 15. The CPICH divides up into a mandatory Primary Common Pilot Channel (P-CPICH) and optional Secondary CPICHs(S-CPICH). The P-CPICH is in use over the entire cell. And it is the first physical channel, where a spreading code is in use. A spreading code is the product of the cell‘s scrambling codeand the channelisation code. The channelisation code is fixed: Cch,256,0. I.e., the UE knows the P-CPICH‘s channelisation code, and it uses the P-CPICH to determine the cell‘s primary scrambling code by trial and error (UE tries 8 SC Codes of the group identified). The P-CPICH is not only used to determine the primary scrambling code. It also acts as- phase reference for most of the physical channels,- measurement reference in the FDD mode (and partially in the TDD mode).There may be zero or several S-CPICHs. Either the cell‘s primary scrambling code or its secondary scrambling codes can be used. In contrast to the P-CPICH, it can be broadcasted just over a part of the cell.


Primary Common Pilot Channel (P-CPICH)

CP

2560 Chips 256 ChipsSynchronisation Channel (SCH)

P-CPICH

10 ms Frame

applied speading code =cell‘s primary scrambling code ⊗

Cch,256,0


P-CPICH

Cell scrambling

code? I get it with trial &

error!

• Phase reference• Measurement reference

CPICH as Measurement Reference


The UE has to perform a set of L1 measurements, some of them refer to the CPICH channel:

• CPICH RSCPRSCP stands for Received Signal Code Power. The UE measures the RSCP on the Primary-CPICH. The reference point for the measurement is the antenna connector of the UE. The CPICH RSCP is a power measurement of the CPICH. The received code power may be high, but it does not yet indicate the quality of the received signal, which depends on the overall noise level.

• UTRA carrier RSSI.RSSI stands for Received Signal Strength Indicator. The UE measures the received wide band power, which includes thermal noise and receiver generated noise. The reference point for the measurements is the antenna connector of the UE.

• CPICH Ec/NoThe CPICH Ec/No is used to determine the „quality“ of the received signal. It gives the received energy per received chip divided by the band‘s power density. The „quality“ is the primary CPICH‘s signal strength in relation to the cell noise. (Please note, that transport channel quality is determined by BLER, BER, etc. )If the UE supports GSM, then it must be capable to make measurements in the GSM bands, too. The measurements are based on the

• GSM carrier RSSIThe wideband measurements are conducted on GSM BCCH carriers.

P-CPICH as Measurement ReferenceReceived Signal Code Power (in dBm)CPICH RSCPreceived energy per chip divided by the power density in the band (in dB)CPICH Ec/No

received wide band power, including thermal noise and noise generated in the receiver

UTRA carrier RSSI

CPICH Ec/No = CPICH RSCPUTRA carrier RSSI

CPICH Ec/No


CPICH RSCP0: -1151: -1142: -113:88: -2789: -26

RSCP values in dBm

UTRA carrier RSSI0: -1101: -1092: -108:71: -3972: -3873: -37

RSSI values in dBm

0: -241: -23.52: -233: -22.5...47: -0.548: 0

Ec/No values in dB

Primary Common Control Physical Channel (P-CCPCH)The UE knows the cell‘s primary scrambling code. It now wants to gain the cell system information (MIB,SIB), which is transmitted on the physical channel P-CCPCH. The channelisation code of the P-CCPCH is also known to the UE, because it must be Cch,256,1 in every cell for every operator. By reading the cell system information on the P-CCPCH, the UE learns everything about the configuration of the remaining common physical channels in the cell, such as the physical channels for paging and random access. As can be seen from the P-CCPCH‘s channelisation code, the data rate for cell system information is fixed. The SCH is transmitted on the first 256 chips of a timeslot, thus creating here a peak load. The cell system information is transmitted in the timeslot except for the first 256 chips. By doing so, a high interference and load at the beginning of the timeslot is avoided. This leads to a net data rate of 27 kbps for the cell system information. Channel estimation is done with the CPICH, so that no pilot sequence is required in the P-CCPCH. (The use of the pilot sequence is explained in the context of the DPDCH later on in this document.) There are also no power control (TPC) bits transmitted to the UE‘s.


Primary Common Control Physical Channel (P-CCPCH)10 ms Frame

CP

2560 Chips 256 ChipsSynchronisation Channel (SCH)

P-CCPCH


P-CCPCH

Finally, I get the cell system

information• channelisation code: Cch,256,1• no TPC, no pilot sequence• 27 kbps (due to off period)• organised in MIBs and SIBs

Primary Common Control Physical Channel (P-CCPCH)


Nokia Parameters for Cell Search

• WCEL: PtxPrimaryCPICHThe parameter determines the transmission power of the primary CPICH channel. It is used as a reference for all common channels. [-20 dBm … 43 dBm], step 1 dB, default: 33dBm (WPA power = 43 dBm)

• WCEL: PtxPrimarySCHTransmission power of the primary synchronization channel, the value is relative to primary CPICH transmission power.[-35 dB … 15 dB], step size 0.1 dB, default: -3 dB

• WCEL: PtxSecSCHTransmission power of the secondary synchronization channel, the value is relative to primary CPICH transmission power.[-35 dB… 15 dB], step size 0.1 dB, default: -3 dB


Nokia Parameters for Cell Search

• WCEL: PtxPrimaryCCPCHThis is the transmission power of the primary CCPCH channel, thevalue is relative to primary CPICH transmission power.[-35 dB … 15 dB], step size 0.1 dB, default: -5 dB

• WCEL: PriScrCodeIdentifies the downlink scrambling code of the Primary CPICH (Common Pilot Channel) of the Cell.[0 ... 511], default: 0 dB


Secondary Common Control Physical Channel (S-CCPCH)

The S-CCPCH can be used to transmit the transport channels

• Forward Access Channel (FACH) and • Paging Channel (PCH).

More than one S-CCPCH can be deployed. The FACH and PCH information can multiplexed on one S-CCPCH – even on the same 10 ms frame -, or they can be carried on different S-CCPCH. The first S-CCPCH must have a spreadingfactor of 256, while the spreading factor of the remaining S-CCPCHs can range between 256 (30 Kbps or 15 Ksps) and 4 (1920 Kbps). UTRAN determines, whether a S-CCPCH has the TFCI (Transport Format Combination Indicator) included (supports variable rates). Please note, that the UE must support both S-CCPCHs with and without TFCI.

S-CCPCH is on air ONLY when there is data to transmit (FACH or Paging)We use SF = 64 120 Kbps (60 Ksps)


Secondary Common Control Physical Channel (S-CCPCH)

10 ms Frame

Slot 0 Slot 1 Slot 2 Slot 14

TFCI(optional) Data Pilot bits


S-CCPCH

• carries PCH and FACH• Multiplexing of PCH and FACH

on one S-CCPCH, even one frame possible

• with and without TFCI (UTRAN set)

• SF = 4..256• (18 different slot formats)• no inner loop power control


S-CCPCH and the Paging Process• The network has detected, that there is data to be transmitted to the UE (MTC).

Both in the RRC idle mode and in the RRC connected mode (e.g. in the sub-state CELL_PCH) a UE may get paged. But how does the mobile know, when it was paged? And in order to save battery power, we don‘t want the UE to listen permanently to paging channel – instead, we want to have discontinuous reception (DRX) of paging messages. But when and where does the UE listen to the paging messages?

• Cell system information is broadcasted via the P-CCPCH. The cell system information is organised in System Information Blocks (SIB). SIB5 informs the mobile phones about the common channel configuration, including a list of S-CCPCH descriptions. The first 1 to K entries transmit the (transport channel) PCH, while the remaining S-CCPCH in the list hold no paging information.

• The UE determines the S-CCPCH, where it is paged, by its IMSI and the number of PCH carrying S-CCPCHs K. When paging the UE, the RNC knows the UE‘s IMSI, too, so that it can put the paging message on the correct PCH transport channel.

• Discontinuous Reception (DRX) of paging messages is supported. A DRX cycle length k has to be set in the network planning process for the cs domain, psdomain, and UTRAN. k ranges between 3 and 9. If for instance k=6, then the UE is paged every 2k = 640 ms. If the UE is in the idle mode, it takes the smaller k-value of either the cs- or ps-domain. If the UE is in the connected mode, it has to select the smallest k-value of UTRAN and the CN, it is not connected to.

S-CCPCH and the Paging Process


Node B

UTRANBCCH (SIB 5)common

channeldefinition,

including

S-CCPCH carrying one PCH



S-CCPCH without PCH

S-CCPCH without PCH

a lists ofUE

Index of S-CCPCHs

01

K-1

UE‘s paging channel:Index = IMSI mod K

e.g. if IMSI mod K = 1 „my pagingchannel“

RNC

The Paging Process


Paging Indicator Channel (PICH)UMTS provides the terminals with an efficient sleep mode operation. The UEs do not have to read and process the content, transmitted during their paging occasion on their S-CCPCH. Each S-CCPCH, which is used for paging, has an associated Paging Indicator Channel (PICH). A PICH is a physical channel, which carries paging indicators. A set of (paging indicator) bits within the PICH indicate to a UE, whether there is a paging occasion for it. Only then, the UE listens to the S-CCPCH frame, which is transmitted 7680 chips after the PICH frame in order to see, whether there is indeed a paging message for it. The PICH is used with spreading factor 256. 300 bits are transmitted in a 10 ms frame, and 288 of them are used for paging indication. The UE was informed by the BCCH, how many paging indicators exist on a 10 ms frame. The number of paging indicator Np can be 18, 32, 72, and 144, and is set by the operator as part of the network planning process. The higher Np, the more paging indicators exist, the more paging groups exist, among which UEs can be distributed on. Consequently, the lower the probability, that a UE reacts on a paging indicator, while there is no paging message in the associated S-CCPCH frame. But a high number of paging indicators results in a comparatively high output power for the PICH, because less bits exists within a paging indicator to indicate the paging event. The operator then also has to consider, if he has to increase the number of paging attempts.

S-CCPCH and its associated PICH

PICH frame

S-CCPCH frame, associated with PICH frame

τPICH= 7680chips

b287 b288 b299b286b0 b1

for paging indication no transmission

τS-CCPCH

80Company Confidential{b2q, b2q+1} = {1,1} {b2q, b2q+1} = {0,0}

# of pagingindicators per frame

(Np)

Subscribers withPq indicator

paged =>18 (16 bits)32 (8 bits)72 (4 bits)144 (2 bits)

Subscribers withPq indicatornot paged =>

{b4q, …, b4q+3} = {1,1,…,1} {b4q, …, b4q+3} = {0,0,…,0}

{b8q, …, b8q+7} = {1,1,…,1} {b8q, …, b8q+7} = {0,0,…,0}

{b16q, …,b16q+15} = {1,1,…,1} {b16q, …,b16q+15} = {0,0,…,0}

Nokia Parameters for S-CCPCH and Paging

RAN 1 & RAN1.5 support data rates of 15, 30, and 60 ksym/s for the S-CCPCH. FACH Open Loop power control can be implemented only if the S-CCPCH is dedicated, uplink PC information through the RACH (RAN 2)

• WCEL: NbrOfSCCPCHsThe parameter defines how many S-CCPCH are configured for the given cell.Range: [1,2], step: 1; default = 1 (1 = FACH&PCH; 2 = FACH on 1st / PCH on 2nd)

• WCEL: PtxSCCPCH1 (carries FACH & PCH)This is the transmission power of the 1st S-CCPCH channel, the value is relative to primary CPICH transmission power.Range: [-35 dB … 15 dB] , step size 0.1 dB, default: - 5dB

• WCEL: PtxSCCPCH2 (carries PCH only)This is the transmission power of the 2nd S-CCPCH channel, the value is relative to primary CPICH transmission power.Range: [-35 dB … 15 dB] , step size 0.1 dB, default: - 5dB


Nokia Parameters for S-CCPCH and Paging

• WCEL: PtxPICHThis is the transmission power of the PICH channel. It carries the paging indicatorswhich tell the UE to read the paging message from the associatedsecondary CCPCH. This parameter is part of SIB 5.[-10 dB..5 dB]; step 1 dB; default: -8 dB (with Np =72)NPRepetition of PICH bits[18, 36, 72, 144] with relative power [-10, -10, -8, -5] dB

• RNC: CNDRXLengthThe DRX cycle length used for CN domain to count paging occasions for discontinuous reception. This parameter is given for CS domain and PS domain separately. This parameter is part of SIB 1.[640, 1280, 2560, 5120] ms; default = 640 ms.

• WCEL: UTRAN_DRX_lengthThe DRX cycle length used by UTRAN to count paging occasions fordiscontinuous reception.[80, 160, 320, 640, 1280, 2560, 5120] ms; default = 320 ms



FACH and S-CCPCHThe transport channel Forward Access Channel (FACH) is used, when relatively small amounts of

data have to be transmitted from the network to the UE. In-band signalling is used to indicate, which UE is the recipient of the transmitted data (see MAC PDU with UE-ID type). This common downlink channel is used without (fast) closed loop power control and is available all over the cell. FACH data is transmitted in one or several S-CCPCHs. FACH and PCH data can be multiplexed on one S-CCPCH, but they can also be be transmitted on different S-CCPCHs.

The FACH is only transmitted downlink. The FACH is organised in FACH Data Frames via the Iub-interface. Each FACH Data Frames holds the Transmission Blocks for one TFS. The used TFS is identified by the TFI. A TFI is associated with one Transmission Time Interval (TTI), which can be either 10, 20, 40 or 80 ms. The TTI identifies the interleaving time on the radio interface. A FACH Data Frame has header fields, which identify the CFN, TFI, and the Transmit Power Level.

The Transmit Power Level gives the preferred transmission power level for the FACH and for the TTI time. The values specified here range between 0 and 25.5 dB, with a step size of 0.1 dB. The value is taken as a negative offset to the maximum power configured for the S-CCPCHs, specified for the FACH.

The pilot bits and the TFCI-field may have a relative power offset to the power of the data field, which may vary in time. (The offset is determined by the network.) The power offsets are set by the NBAP message COMMON TRANSPORT CHANNEL SETUP REQUEST, which is sent from the RNC to the Node B. There are two power offset information included:

• PO1: defines the power offset for the TFCI bits; it ranges between 0 and 6 dB with a 0.25 step size.

• PO3: defines the power offset for the pilot bits; it ranges between 0 and 6 dB with a 0.25 step size.

Another important parameter is the maximum allowed power on the FACH: MAX FACH Power.

FACH and S-CCPCH


Node B RNC

FACH Data FrameCFNTFI

Transmit Power Level

TB TB

Iub

UE

Uu

TFCI(optional) Data

Pilot bits

max. transmitpower for S-CCPCH

0..25.5 dB,

step size 0.1

Transmit Power Level

PO1 PO3

Power offsets for TFCI and

TPC defined during

channel setup

Nokia Parameters for S-CCPCH Power Setting

Currently, either one or two S-CCPCHs are supported. • WCEL: PowerOffsetSCCPCHTFCI

Defines the power offset for the TFCI symbols relative to the downlink transmission power of a Secondary CCPCH. This parameter is part of SIB 5.P01_15/30/6015 ksps: [0..6 dB]; step 0.25 dB; default: 2 dB30 ksps : [0..6 dB]; step 0.25 dB; default: 3 dB60 ksps : [0..6 dB]; step 0.25 dB; default: 4 dB

• WCEL: PowerOffsetSCCPCHPilotDefines the power offset for the pilot symbols relative to the downlink transmission power of a Secondary CCPCH. This parameter is part of SIB 5.P03_15/30/6015 ksps : [0..6 dB]; step 0.25 dB; default: 2 dB30 ksps : [0..6 dB]; step 0.25 dB; default: 3 dB60 ksps : [0..6 dB]; step 0.25 dB; default: 4 dB


Code Tree Capacity


Part VPower Control


Effect of TX & RX Powers on Interference Levels

Downlink transmission power = Interference to the network

Uplink received power = Interference to own cell users

Uplink transmission power = Interference to other cells


Since every TX and RX power is causing interference to others, PC is necessary to limit the interference

CDMA Fundamentals : Power Control


MS2

Pr,2Pr,1

MS1

P = 21 dBmP = 21 dBm

Near-Far Problem

PL1 = 100 dB

PL2 = 90 dBPr,1 = EIRP(MS1) - PL1 = 21 - 100 = -79 dBmPr,2 = EIRP(MS2) - PL2 = 21 - 90 = -69 dBm

(S/N)1 = Pr,1 - Pr,2 = -10 dB(S/N)2 = Pr,2 - Pr,1 = +10 dB

MS2 must be Power Controlled by -10 dB to have the same S/N for both users MS1 and MS2

Near-Far Effect


Purpose of Power Control in WCDMA


Physical Random Access (Open loop Power Control)Outer Loop Power Control

Fast Closed Loop (Inner) Power Control



Physical Random Access (Open loop Power Control)In the random access (based on Slotted ALOHA approach with fast acquisition

indication) , initiated by the UE (MOC), two physical channels are involved:

• Physical Random Access Channel (PRACH)The physical random access is decomposed into the transmission of preambles in the uplink. Each preamble is transmitted with a higher output power as the preceding one. After the transmission of a preamble, the UE waits for a response by the Node B. This response is sent with the physical channel Acquisition Indication Channel (AICH), telling the UE, that the Node B as acquired the preamble transmission of the random access. Thereafter, the UE sends the message itself, which is the RACH/CCCH of the higher layers. The preambles are used to allow the UE to start the access with a very low output power. If it had started with a too high transmission output power, it would have caused interference to the ongoing transmissions in the serving and neighbouring cells. Please note, that the PRACH is not only used to establish a signalling connection to UTRAN. It can be also used to transmit very small amounts of user data.

• Acquisition Indication Channel (AICH)This physical channel indicates to the UE, that it has received the PRACH preamble and is now waiting for the PRACH message part.


Random Access – the Working Principle

Node BUEPRACH (preamble)

PRACH (preamble)

PRACH (preamble)

PRACH (message part)

AICH

No responseby theNode B

No responseby theNode B

I just detecteda PRACH preamble

OLA!

Random Access Timing


The properties of the PRACH are broadcasted (SIB5, SIB6). The candidate PRACH is randomly selected (if there are several PRACH advertised in the cell) as well as the access slots (= 2 TIME SLOTS) within the PRACH. 15 access slots are given in a PRACH, each access slot lasting two timeslots or 5120 chips. In other words, the access slots stretch over two 10 ms frames. A PRACH preamble, which is transmitted in an access slot, has a length of 4096 chips. Also the AICH is organised in (AICH) access slots, which stretch over two timeslots. AICH access slots are time aligned with the P-CCPCH. The UE sends one preamble in uplink access slot n. It expects to receive a response from the Node B in the downlink (AICH) access slot n, τp-a chips later on. If there is no response, the UE sends the next preamble τp-p chips after the first one. The maximum numbers of preambles in one preamble access attempt can be set between 1 and 64. The number of PRACH preamble cycles can be set between 1 and 32. If the AICH_Transmission_Timing parameter in the SIB is set to BCCH SIB5 & SIB6 to•0,then, the minimum preamble-to-preamble distance is 3 access slots, the minimum preamble-to-message distance is 3 access slots, and the preamble-to-acquisition indication is 3 timeslots.•1,then, the minimum preamble-to-preamble distance is 4 access slots, the minimum preamble-to-message distance is 4 access slots, and the preamble-to-acquisition indication is 5 timeslots.

Random Access Timing

SFN mod 2 = 0 SFN mod 2 = 0SFN mod 2 = 1P-CCPCH


AICH accessslots0 1 1282 1175 964 13103 14 0 1 2 75 643

5120chips

Preamble

5120 chips

Preamble

AS # i

4096 chips

preamble-to-preambledistance τp-p

UE point of view

PRACHaccess slots

AICHaccess slots

Messagepart

preamble-to-messagedistance τp-m

AcquisitionIndication

preamble-to-AIdistance τp-a

(distances depend on AICH_Transmission_Timing )

AS # i

PRACH Power SettingPreamble_Initial_Power =

UL interference + Primary CPICH TX power – CPICH_RSCP

+ Constant Value

UL interferenceat Node B

1st preamble: power setting

attenuation in the DL estimated receive level

Constant Value

Pre-amble

MessagepartPre-

amble

Pre-amble

Pp-p Pp-mPp-p


1..8 dB

-5..10 dB

# of preambles: 1..64 # of preamble cycles: 1..32

Nokia Parameters Related to the PRACH and AICH

WCEL: PRACHRequiredReceivedCIThis UL required received C/I value is used by the UE to calculate the initial output power on PRACH according to the Open loop power control procedure. This parameter is part of SIB 5.[-35 dB..-10 dB]; step 1 dB; default -25 dB. We use - 20

WCEL: PowerRampSteponPRACHPreambleUE increases the preamble transmission power when no acquisitionindicator is received by UE in AICH channel. This parameter is part of SIB 5.[1dB..8dB]; step 1 dB; default: 2 dB. We use 1

• WCEL: PowerOffsetLastPreamblePrachMessageThe power offset between the last transmitted preamble and the control part of the PRACH message.[-5 dB..10 dB]; step 1 dB; default 2dB

• WCEL: PRACH_preamble_retransThe maximum number of preambles allowed in one preamble ramping cycle, which is part of SIB5/6.[1 ... 64]; step 1; default 8. We use 7




• WCEL: RACH_tx_MaxMaximum number of RACH preamble cycles defines how many times the PRACH pre-amble ramping procedure can be repeated before UE MAC reports a failure on RACH transmission to higher layers. This message is part of SIB5/6.[1 ... 32]; default 8. We use 16

WCEL: PRACHScramblingCodeThe scrambling code for the preamble part and the message part of a PRACH Channel, which is part of SIB5/6.[0 ... 15]; default 0.

• WCEL: AllowedPreambleSignaturesThe preamble part in a PRACH channel carries one of 16 differentorthogonal complex signatures. Nokia Node B restrictions: A maximum of four signatures can be allowed (16 bit field).[0 ... 61440]; default 15. We use 4

• WCEL: AllowedRACHSubChannelsA RACH sub-channel defines a sub-set of the total set of access slots (12 bit field).[0 ... 4095]; default 4095.


• WCEL: PtxAICHThis is the transmission power of one Acquisition Indicator (AI) compared to CPICH power. This parameter is part of SIB 5.[-22 ... 5] dB, step 1 dB; default: -8 dB.

• WCEL: AICHTraTimeAICH transmission timing defines the delay between the reception of a PRACH access slot including a correctly detected preamble and the transmission of the Acquisition Indicator in the AICH.0 ( Delay is 0 AS), 1 ( Delay is 1 AS) ;default 0.

• WCEL: RACH_Tx_NB01minIn case that a negative acknowledgement has been received by UE on AICH a backoff timer TBO1 is started to determine when the next RACH transmission attempt will be started. The backoff timer TBO1 is set to an integer number NBO1 of 10 ms time intervals, randomly drawn within an Interval 0 ≤ NB01min ≤ NBO1 ≤ NB01max (with uniform distribution).[0 ... 50]; default: 0.

• WCEL: RACH_Tx_NB01max[0 ... 50]; default: 50.


Outer Loop Power Control

OL PC is needed to keep the quality of the communication at the required level (BLER, SIR, BER,…) by setting the target (SIR) for the fast power control. It aims at providing the required quality: no worse, no better. Too high quality would waste capacity. It is needed in both UL and DL since there is Fast PC (Closed Loop or Inner Loop) in both UL and DL



In RADIO BEARER SETUP Message you can find the Target BLER (for the DL)For AMR and PS 128 = 1% BLER, CS T (VIDEO) = 0.1%, CS NT = 0.2%



UL Outer Loop Power Control Algorithm

Case of Soft Handover

UL Outer Loop Power Control Algorithm


UL OL PC: BLER Eb/No (Initial SIR Target, SIR Target Max, SIR Target Min)


DL Outer Loop Power Control

DeltaSIR(1,2), DeltaSIR after (1,2),…..


The adjustments of the SIR Target done by the UE is a proprietary algorithm that provides the same measured quality (BLER) as the quality target set by the RNC


• UL (Near-Far Problem): UE1 and UE2 operate within the same frequency, separable at the base station only by their respective spreading codes. It may happen that UE1 at the cell edge suffers a path loss, say 70 dB above that of UE2 which is near to NodeB. If there were no mechanism for UE1 and UE2 to be power-controlled to the SAME level at the NodeB, UE2 could easily overshoot UE1 and thus a large part of the cell. Power control tries to equalizes the Rx power per bit of all UE’s at NodeB. Since Fast Fading is uncorrelated between uplink and downlink (large freq separation between uland dl bands in FDD) we can not use only a method based on Open Loop Power Control. Solution: Closed Loop PC: in UL the NodeB performs frequent (1.5 KHz) estimates of the received SIR and compares it to the SIR Target (calculated during Outer Loop PC).

• DL: We do not have Near-Far Problem due to one-to-many scenario: all the signals within one cell originate from one NodeB to all mobiles. However it is desirable to provide a marginal amount of additional power to UE at the cell edge, as they suffer from increased other-cell-interference.



DL Fast Closed (Inner) Loop Power ControlInner loop power control is also often called (fast) closed loop power control. It takes place

between the UE and the Node B. We talk about UL inner loop power control, when the Node B returns immediately after the reception of a UE‘s signal a power control command to the UE. By doing so, the UE‘s SIR ratio is kept at a certain level (the details will be discussed later on in the course). DL inner loop power control control is more complex. When the UE receives the transmission of the Node B, the UE returns immediately a transmission power control command to the Node B, telling the Node B either to increase or decrease its output power for the UE‘s DPCH. The Node B‘s transmission power can be changed by 0.5, 1, 1.5 or 2 dB. 1 dB must be supported by the equipment. If other step sizes are supported or selected, depends on manufacturer or operator. The transmission output power for a DPCH has to be balanced for the PICH, which adds to the power step size.

There are two downlink inner loop power control modes:• DPC_MODE = 0: Each timeslot, a unique TPC command is sent uplink.• DPC_MODE = 1: 3 consecutive timeslots, the same TPC command is transmitted. One reason for the UE to request a higher output power is given, when the QoS target

has not been met. It requests the Node B to transmit with a higher output power, hoping to increase the quality of the connection due to an increased SIR at the UE‘s receiver. But this also increases the interference level for other phones in the cell and neighbouring cells. The operator can decide, whether to set the parameter Limited Power Increase Used. If used, the operator can limit the output power raise within a time period.

DL Fast Closed (Inner) Loop PC Algorithm


Every 1500 Hz (time slot)UE measures SIR= (RSCP/ISCP)×SF

Downlink Inner Loop Power Control

DPC_MODE = 0

unique TPC commandper TS

DPC_MODE = 1

same TPC over 3 TS,then new command

two modescell

TPC

TPCest per1 TS / 3 TS


UL Inner Loop Power Control

time

SIRest

SIRtarget

TCP = 1

TCP = 1

TCP = 0

TCP = 0 TPC ⇒TPC_cmd

in FDD mode:1500 times per

second112

Company Confidential

UL Fast Closed (Inner) Loop PC Algorithm


UL Inner Loop Power ControlPower Control Algorithm 1 is applied in medium speed environments. Here, the UE

is commanded to modify its transmit power every timeslot. If the received TPC value is 1, the UE increases the transmission output at the DPCCH by ∆DPCCH, otherwise it decreases it by ∆DPCCH. The ∆DPCCH is either 1 or 2 dB, as set by the higher layer protocols. TPC values from the same radio link set represent one TLC_cmd. TPC_cmds from different radio link sets have to be weighted, if there isno reliable interpretation.

Power Control Algorithm 2 (300 times/s) was specified to allow smaller step sizes in the power control in comparison to PCA1. This is necessary in very low and high speed environments. In these environments, PCA1 may result in oscillating around the target SIR.

PCA2 changes only with every 5th timeslot, i.e. the TPC_cmd is set to 0 the first 4 timeslots. In timeslot 5, the TPC_cmd is –1, 0, or 1. For each radio set, the TPC_cmd is temporarily determined. This can be seen in the next figure. The temporary transmission power commands (TPC_temp) are combined as can be seen in the figure after the next one. Here you can see, how the final TPC_cmd is determined.


UL Inner Loop Power Control Algorithms (1 and 2)


• The optimum PC step size varies depending on the UE speed. For a given quality target, the best UL PC step size is the one that results in the lowest target SIR. With an update rate of 1500 Hz, a PC step size of 1dB can effectively track a typical Rayleigh fading channel up to Doppler frequency of about 55 Hz (30 Km/h). At higher speeds, up to about 80 Km/h, a PC step size of 2dB gives better results.

• For speeds greater than 80 Km/h the inner loop PC can no longer follow the fades and just introduces noise into the UL transmission. This adverse effect on the UL performance could be reduced if a PC step size smaller than 1 dB was employed. Also, for UE speeds lower than about 3 Km/h where the fading rate of the channel is very small, a smaller step size is more beneficial.

• Algorithm 1 is used when the UE speed is sufficiently low to compensate for the fading of the channel (PC step size should be 1 or 2 dB)

• Algorithm 2 was designed for emulating the effect of using a PC step size smaller than 1 dB and can be used to compensate for the slow fading trend of the propagation channel rather than rapid fluctuations. It performs better than Alg 1 when the UE moves faster than 80 Km/h or slower than 3 Km/h. The UE does not change its transmission power until it has received 5 consecutive TPC commands.

UL Inner Loop Power Control

PCA2 PCA1 PCA2

algorithms for processing power control commands

TPC_cmd

PCA1TPC_cmd for each TSTPC_cmd values: +1, -1step size ∆ TPC: 1dB or 2dB

PCA2TPC_cmd for 5th TSTPC_cmd values: +1, 0, -1step size ∆ TPC: 1dB

UL DPCCH power adjustment: ∆DPCCH = ∆ TPC × TPC_cmd

km/h0 ≈ 3 ≈ 80Rayleigh fading can be compensated116


UL Inner Loop Power Control Algorithm 1


Example: reliable transmission

Cell 1Cell 2

Cell 3

TPC1 = 1 TPC3 = 0

TPC3 = 1

⇒TPC_cmd = -1

UL Inner Loop Power Control Algorithm 2 (Part 1)


TPC = 1TPC = 1TPC = 1TPC = 1TPC = 1TPC = 1TPC = 0TPC = 1TPC = 0TPC = 1TPC = 0TPC = 0TPC = 0TPC = 0TPC = 0

TPC_temp00001000000000-1

• if all TPC-values = 1⇒ TPC_temp = +1

• if all TPC-values = 0⇒ TPC_temp = -1

• otherwise⇒ TPC_temp = 0

UL Inner Loop Power Control Algorithm 2 (Part 2)

TPC_temp1 TPC_temp2 TPC_temp3

Example:

N = 3 cells

∑=

N

iiN 1

TPC_temp1

-1


-0.5 0.50 1

-1 10TPC_cmd =

Part VIDedicated Physical

Channels



Downlink Dedicated Physical Channel (DPCH)The downlink DPCH is used to transmit the DCH data. Control information and user

data are time multiplexed. The control data is associated with the Dedicated Physical Control Channel (DPCCH), while the user data is associated with the Dedicated Physical Data Channel (DPDCH).

The transmission is organised in 10 ms radio frames, which are divided into 15 timeslots. The timeslot length is 2560 chips. Within each timeslot, following fields can be found:

• Data field 1 and data field 2, which carry DPDCH information• Transmission Power Control (TPC) bit field• Transport Format Combination Indicator (TFCI) field, which is optional• Pilot bitsThe exact length of the fields depends on the slot format, which is determined by

higher layers. The TFCI is optional, because it is not required for services with fixed data rates. Slot format are also defined for the compressed mode; hereby different slot formats are in used, when compression is archived by a changed spreading factor or a changed puncturing scheme.

The pilot sequence is used for channel estimation as well as for the SIR ratio determination within the inner loop power control. The number of the pilot bits can be 2, 4, 8 and 16 – it is adjusted with the spreading factor. A similar adjustment is done for the TPC value; its bit numbers range between 2, 4 and 8.

The spreading factor for a DPCH can range between 4 and 512. The spreading factor can be changed every TTI period.

Superframes last 720 ms and were introduced for GSM-UMTS handover support.

Downlink Dedicated Physical Channel (DPCH)

Superframe = 720 ms

Radio Frame0

Radio Frame1

Radio Frame2

Radio Frame71

10 ms Frame


TPCbits Pilot bits

TFCIbits

(optional)Data 2 bitsData 1 bits


DPDCHDPDCH DPCCH DPCCH• 17 different slot formats• Compressed mode slot

format for changed SF & changed puncturing

2,4,8,16 bits (SIR estimation)2,4,8 bits



Following features are supported in the downlink:• Blind rate detection, and• Discontinuous transmission.Rate matching is done to the maximum bit rate of the connection. Lower bit rates are

possible, including the option of discontinuous transmission. Please note, that audible interference imposes no problem in the downlink, since Common Channels have continuous transmission.

Multicode usage:Several physical channels can be allocated in the downlink to one UE. This can

occur, when several DPCH are combined in one CCTrCH in the PHY layer, and the data rate of the CCTrCH exceeds the maximum data rates allowed for the physical channels. Then, on all downlink DPCHs, the same spreading factor is used. Also the downlink transmission of the DPCHs takes place synchronous. One DPCH carries DPDCH and DPCCH information, while on the remaining DPCHs, no DPCCH information is transmitted.

But also in the case, when several DPCHs with different spreading factors are in use, the first DPCH carries the DPCCH information, while in the remaining DPCHs, this information is omitted (discontinuous transmission).

Multicode usage is not implemented in RAN1.

Physical Layer Bit Rates (Downlink)

Spreading factor

Channel symbol

rate(ksps)

Channel bit rate(kbps)

DPDCH channel bit rate range

(kbps)

Maximum user data rate with ½-

rate coding (approx.)

512 7.5 15 3–6 1–3 kbps256 15 30 12–24 6–12 kbps128 30 60 42–51 20–24 kbps64 60 120 90 45 kbps32 120 240 210 105 kbps16 240 480 432 215 kbps8 480 960 912 456 kbps4 960 1920 1872 936 kbps

4, with 3 parallel codes

2880 5760 5616 2.8 Mbps

• The number of orthogonal channelization codes = Spreading factor

Half rate speechFull rate speech

128 kbps384 kbps

2 Mbps



TS TS

maximum bit rate

TS TS TS

discontinuous transmission with lower bit rate

Multicode usage:

TS TS TS


TS TS TS

DPCH 1

DPCH 2

DPCH 3


Power Offsets for the DPCH

Node B RNC

DCH Data Frame

Iub

UE

Uu

PO1

NBAP: RADIO LINK SETUP REQUEST

TPCbits Pilot bits

TFCIbits

(optional) Data 2 bitsData 1 bits

PO3PO2

• Power offsets• TFCS• DL DPCH slot

format• FDD DL TPC

step size

P0x: 0..6 dBstep size: 0.25

dB

Nokia Parameters Related to DPCHs• RNC: PowerOffsetDLdpcchPilot

The parameter defines the power offset for the pilot symbols in relative to the data symbols in dedicated downlink physical channel [0 … 6 dB]; step size 0.25 dB; default: 3 dB for 12.2 kbps

• RNC: PowerOffsetDLdpcchTpc,The parameter defines the power offset for the TPC symbols relative to the data symbols in dedicated downlink physical channel[0 … 6 dB]; step size 0.25 dB; default: 3 dB for 12.2 kbps

• RNC: PowerOffsetDLdpcchTfci,The parameter defines the power offset for the TFCI symbols relative to the data symbols in dedicated downlink physical channel. [0 … 6 dB], step size 0.25 dB; default: 3 dB for 12.2 kbps


Uplink Dedicated Physical Channels


The uplink dedicated physical channel transmission, we identify two types of physical channels:Dedicated Physical Control Channel (DPCCH),which is always transmitted with spreading factor 256 (3840/256=15Ksps=15Kbps). Following fields are defined on the DPCCH:- pilot bits for channel estimation. Their number can be 3, 4, 5, 6, 7 or 8. - Transmitter Power Control (TPC), with either one or two bits- Transport Format Combination Indicator (TFCI), which is optional, and a- Feedback Indicator (FBI). Bits can be set for the closed loop mode transmit diversity and site selection diversity transmission (SSDT)6 different slot formats were specified for the DPCCH. Variations exist for the compressed mode. Dedicated Physical Data Channel (DPDCH), which is used for user data transfer. Its spreading factor ranges between 4 and 256. 7 different solt formats are defined, which are set by the higher layers.The DPCCH and DPDCH are combined by I/Q code multiplexing with each multiframe.

Multicode usage is possible. If applied, additonal DPDCH are added to the uplink transmission, but no additional DPCCHs! The maximum number of DPDCH is 6; when more than one DPDCH is used (Multicodes) they all use SF = 4.

The transmission itself is organised in 10 ms radio frames, which are divided into 15 timeslots. The timeslot length is 2560 chips.

Superframe = 720 ms


10 ms Frame

TPCbitsPilot bits TFCI bits

(optional)

Data 1 bits

Radio Frame0

Radio Frame1

Radio Frame2

Radio Frame71

DPDCH


DPCCH FBI bits

• 7 different slot formats

• 6 different slot formats

• Compressed mode slot format for changed SF & changed puncturing

Feedback Indicator for• Closed loop mode transmit

diversity, &• Site selection diversity

transmission (SSDT)

Uplink Dedicated Physical Channels


Discontinuous Transmission and Power OffsetsDiscontinuous transmission (DTX) is supported for the DCH both uplink and

downlink. If DTX is applied in the downlink – as it is done with speech – then 3000 bursts are generated in one second. (1500 times the pilot sequence, 1500 times the TPC bits) This causes two problems:

• Inter-frequency interference, caused by the burst generation. At the Node B, the problem can be overcome with exquisite filter equipment. This filter equipment is expensive and heavy. Therefore it cannot be applied in the UE. The UE‘s solution is I/Q code multiplexing, with a continuous transmission for the DPCCH. DPDCH changes can still occur, but they are limited to the TTI period. The minimum TTI period is 10 ms. The same effects can be observed, then the DPDCH data rate and with it its output power is changing.

• 3000 bursts causes audible interference with other equipment – just see for example GSM. By reducing the changes to the TTI period, the audible interference is reduced, too.

Determination of the power difference between the DPCCH and DPDCHI/Q code multiplexing is done in the uplink, i.e. the DPCCH and DPDCH are transmitted with different codes (and possible with different spreading factors). Gain factors are specified: βc is the gain factor for the DPCCH, while βd is the gain factor for the DPDCH. The gain factors may vary for each TFC. There are two ways, how the UE may learn about the gain factors:

• The gain factors are signalled for each TFC.If so, the nominal power relation Aj between the DPDCH and DPCCH is βd/βc.

• The gain factor is calculated based on reference TFCs.

DPCCH

DPDCH

DPCCH

DPDCH

DPCCH

DPDCH


TTI TTI TTI

UL DPDCH/DPCH Power Difference:

DPCCH

DPDCH

=βd

βc=Nominal Power Relation Aj

two methods to determine the gain factors:• signalled for each TFCs• calculation based on reference TFCs

Discontinuous Transmission and Power Offsets


Initial Uplink DCH TransmissionWhen we look to the PRACH, we can see, that a preambles were used to avoid UEs

to access UTRAN with a too high initial transmission power. The same principle is applied for the DPCH. After PRACH procedure the UE transmits between 0 to 7 radio frames only the DPCCH uplink (the period is called DPCCH power control Preamble), before the DPDCH is code multiplexed. The number of radio frames is set by the higher layers (RRC resp. the operator). Also for this period of time, only DPCCH can be found in the downlink.The UE can be also informed about a delay regarding RRC signalling – this is called SRB delay, which can also last 0 to 7 radio frames. The SRB delay followsafter the DPCCH preamble.

How to set the the transmission power of the first UL DPCCH preamble? Its power level is

DPCCH_Initial_power = – CPICH_RSCP + DPCCH_Power_offsetThe DPCCH Power Offset is retrieved from RRC messages. It’s value ranges between –164 and –6 dB (step size 2 dB). CPICH_RSCP is the received signal code power on the P-CPICH, measured by the UE.

Initial Uplink DCH Transmission

T0

DPCCH only DPCCH & DPDCH

receptionat UE

trans-mission

at UE

0 to 7 frames for power control preamble

DPCCH only, always based on PCA1

DPCCH & DPDCHPCA based on RRC


DPCCH_Initial_power = – CPICH_RSCP + DPCCH_Power_offset

Radio frame timing and access slot timing of downlink physical channels


k:th S-CCPCH

AICH access slots

Secondary SCH

Primary SCH

τ S-CCPCH,k

10 ms

τPICH

#0 #1 #2 #3 #14#13#12#11#10#9#8 #7#6#5#4

Radio frame with (SFN modulo 2) = 0 Radio frame with (SFN modulo 2) = 1

τ DPCH,n

P-CCPCH

Any CPICH

PICH for k:th S-CCPCH

Any PDSCH

n:th DPCH

10 ms

Subframe# 0

HS-SCCH Subframes

Subframe#1

Subframe#2

Subframe#3

Subframe#4

Part VIIWCDMA Planning


Radio Network Planning Process

CoveragePlanning andSite Selection

Path lossprediction

Cell isolationoptimisation

System Dimensioning

DEFINITION PLANNING and IMPLEMENTATION

Traffic distribution

Pilot PowerSoft handover

Blocking objectives

NetworkOptimisation

O & M

Surveymeasurements

Statisticalperformanceanalysis

Capacity Optimisation

Requirementsand strategyfor coverage,quality andcapacity,per service

Coverageoptimisation

CoveragePlanning andSite Selection

Path lossprediction

Cell isolationoptimisation

System Dimensioning

DEFINITION PLANNING and IMPLEMENTATION

Traffic distribution

Pilot PowerSoft handover

Blocking objectives

NetworkOptimisation

O & M

Surveymeasurements

Statisticalperformanceanalysis

Capacity Optimisation

Requirementsand strategyfor coverage,quality andcapacity,per service

Coverageoptimisation


Planning issues• Planning should meet current standards and demands and also comply with future

requirements.• Uncertainty of future traffic growth and service needs.• High bit rate services require knowledge of coverage and capacity enhancements

methods.• Real constraints– Coexistence and co-operation of 2G and 3G for old operators.– Environmental constraints for new operators.• Network planning depends not only on the coverage but also on load.

Objectives of Radio network planning• Capacity:– To support the subscriber traffic with sufficiently low blocking and delay.• Coverage:– To obtain the ability of the network ensure the availability of the service in the entire

service area.• Quality:– Linking the capacity and the coverage and still provide the required QoS.• Costs:– To enable an economical network implementation when the service is established and a

controlled network expansion during the life cycle of the network.


Planning methods• Preparation phase– Defining coverage and capacity objectives– Selection of network planning strategies– Initial design and operation parameters• Initial dimensioning– First and most rapid evaluation of the network elements count and capacity of

these elements– Offered traffic estimation– Joint capacity coverage estimation• Detailed planning– Detailed coverage capacity estimation– Iterative coverage analysis– Planning for codes and powers• Optimization– Setting the parameters

• Soft handover• Power control• Verification of the static simulator with the dynamic simulator


A strategy for dimensioning• Plan for adequate load and number of sites.• Enable optimized site selection.• Avoid adding new sites too soon.• Allow better utilization of spectrum.• Recommended load factor 30- 70 %


Dimensioning process


Capacity&Coverage Trade Off


•The coverage for a WCDMA system is generally limited by the uplink. This is because the maximum output power of the mobile is lower than for the base station, so the base station can reach longer than the mobile can.

•Capacity is generally limited by the downlink. This is because better receiver techniques can be used in the base station than in the mobile. Since most forecasts predict an asymmetric load where the users download data to a larger extent than sending, the downlink will be most important from a capacity point of view.

•Capacity and coverage is closely related in a WCDMA system. When traffic increases, the level of interference in the system increases. To compensate for this, the mobile has to increase its output power in order to defeat the increased noise, or in already at max power, make the connection closer to the base station.

• Due to the increase of traffic, the effective cell area has shrunk. This behavior is known as cell breathing. In an FDMA or TDMA-system this problem does not arise, since coverage and capacity is largely independent.

•To reduce cell breathing interference margins are included when dimensioning the network, which has the effect of increasing site density.

Coverage Limited Uplink• Another way to reduce cell breathing would be to add a frequency, which would

mean that the users could be spread over two or more carriers. Since the different carriers are not interfering with each other, the interference level is reduced, and an increase in capacity or coverage is achieved

• When making the initial design, the aim is to provide a certain capacity, or service level, over an area. One design strategy could be to design a very low-density network, capable of providing low capacity over a wide area.

• This would reduce the number of base stations as compared to building for higher capacity. Since the cost of base stations are a large part of the cost of building a network, minimizing the number of base stations are important.

• On the other hand, it is important to be able to provide attractive services to the customers. This could be difficult if not enough bandwidth is available. Building less dense means that the maximum distance between the mobile and base station is increased, which is the same as allowing a higher maximum path loss between the two.

• A higher path loss between the mobile and the base station can be tolerated if the interference is decreased. If the interference in a cell were reduced by a certain amount of dB, the maximum allowed path loss would increase by the same amount.


Coverage Limited Uplink•Using a propagation model like for example Okumura-Hata, it is possible to convert a change of the interference level into a changed site density, compared to a reference case.

•Table below shows the change in number of sites if the interference margin in the link budget is changed. A negative dB value means that the link budget is worse compared to the reference case, and thus more sites are needed.


Uplink Load FactorInterference degradation margin: describes the amount of increase of interference due to multiple access . It is reserved in the link budget.Can be calculated as the Noise Rise: the ratio of the total received power Itotal to the Noise Power PN


[ ]1,0 Where)1(log10- toequal is (dB) Rise Noise

)/(1

1)1()1(

as written becan factor loaduplink The

connection one offactor load theis ,

:Factor Load Where

11

11 Rise Noise

10

11

1

UL

1

∈−⋅

⋅⋅+

⋅⋅+=⋅+=

=

−=

−==

∑∑

∑

∑

==

=

=

UL

UL

N

j

jjjOb

SN

j jUL

jN

j jUL

ULN

j jN

total

RNEW

NiLi

LL

is

LPI

ηη

υζ

η

η

η

η


Uplink Load FactorDefinitions Recommended Values

N Number of users per cell

Activity Factor of user j at physical layer 0.67 for speech

Eb/No Signal energy per bit divided by noise spectral density that is required to meet a predefined BLER. Noise includes both thermal and interference

Dependent on service, bit rate, mulitpath, fading channel, receive antenna diversity, mobile speed, etc

W WCDMA chip rate 3.84 Mcps

Rj Bit Rate of user j Dependent on service

Sectorisation Gain 1 Sector (Omni): 1; 3 Sectors (90°): 2.57;3 Sectors (65°): 2.87; 3 Sectors (33°): 2.824 Sectors (90°): 3.11; 6 Sectors (65°): 4.70

NS Number of Sectors

i Other cell to own cell interference ratio seen by the base station receiver

Macro Cell with omni antennas: 55%. Macro Cell with 3 sectors: 65%

jυ

ζ

Uplink Noise Rise as a Function of Throughput

Noi

se R

ise

(dB

)

Throughput (Kbps)

123456789

101112

200 400 600 800 1000 1200 1400 1600

Voice (12.2 Kbps)144 Kbps



• For voice services a typical noise rise would be between 1-3 dB, which corresponds to a throughput between 150 kbps and 375 kbps. A network is designed for a certain throughput.

• After some time that throughput is reached, and as a result the noise rise rises over the design value.

• The choice is then to either increase site density, or add more frequencies. Adding a frequency has its own set of problems, most notably that soft handover does not work between frequencies. This problem is less of an issue if new frequencies are added to a number of sites over a wider area.

• The mobile can then move freely on the frequency it has been assigned, and the probability of making a hard inter-frequency handover is reduced

• Assume that traffic increases so that the actual noise rise is 4 dB, 1 dB above the design level. The noise figure needs to be improved, for example down to 2 dB, to improve quality and make room for future capacity demands. In other words, the average throughput per cell needs to be reduced.

• Building more sites, or adding another frequency can do this. • Adding a second frequency would half the throughput for each cell and carrier.

For a 4 dB noise rise the throughput is 450 kbps according to the graph. A new throughput of 450/2 kbps=225 kbps per carrier gives a noise rise of 1.5 dB, an improvement of 2.5 dB. A 2.5 dB lower allowable path loss corresponds roughly to 40% more sites, that is, The cost of building these sites can then be said to be the value of having one extra frequency. Adding a second and a third frequency follows the same pattern, with a slight difference. The relative decrease in noise rise will be lower. When a third frequency is added the traffic is spread over three carriers, and reduced with a third for each frequency.

Coverage Limited Uplink

• It is also possible to do the other way around, that is, build sites less dense to start with. This saves money in the roll out phase, but could cause problems if high capacity is needed in the future. Using figures from the example above, assume a design for a maximum throughput of 375 kbps for one carrier, which corresponds to a noise rise of 3 dB. Using two carriers gives a throughput per carrier of 375/2 kbps=190 kbps, which corresponds to a noise rise of 1.3 dB. The saving is 2.7 dB, which converts to roughly 70% of the original number of sites is needed. This is the same as each site covers approximately 1.4 times the area of the original one carrier site.

Coverage Limited Uplink

0

0.5

1

1.5

2

2.5

3

3.5

32 kbps 64 kbps 144 kbps 384 kbps 1024 kbps 2048 kbps

Rang

e [k

m]

Uplink Coverage of Different Bit Rates


Suburban area with 95% outdoor location probability

Downlink Load Factor

( )[ ]

[ ]1,0 Where)1(log10- toequal is

ceinterferen access multiple todue noise alover therm Rise Noise

-1)/(

10

j1

∈−⋅

+⋅⋅= ∑ =

DL

DL

jN

jj

jObjDL i

RWNE

ηη

αυη


Definitions Recommended Values

N Number of users per cell

Activity Factor of user j at physical layer 0.58 for speech

Eb/No Signal energy per bit divided by noise spectral density that is required to meet a predifinedBLER. Noise includes both thermal and interference

Dependent on service, bit rate, mulitpath, fading channel, receive antenna diversity, mobile speed, etc

W WCDMA chip rate 3.84 Mcps

Rj Bit Rate of user j Dependent on service

Orthogonality of channel of user j Dependent on the multipath propagation1: fully orthogonal 1-path channel0: no orthogonalityITU Vehicular A channel: ~ 50%ITU Pedestrian A channel: ~ 90%

Ratio of other cell to own cell base station power, received by user j

Each user sees a different , depending on its location in the cell and log-normal shadowing. Macro Cell with omni antennas: 55%. Macro Cell with 3 sectors: 65%

jα

jiji

jυ

• Compared to the uplink load equation, the most important new parameter is , which represent the orthogonality factor in the downlink. WCDMA employs orthogonal codes in DL to separate users, and without multipath propagation the orthogonality remains when the base station signal is received by the mobile.

• The DL load factor exhibits very similar behavior to the UL load factor, in the sense that when approaching unity, the system reaches its pole capacity and the noise rise over thermal noise goes to infinity

• For downlink dimensioning, it’s important to estimate the total amount of base station transmission power required. This is based on average transmission power for user

jα

Downlink Load Factor

( )( )

dB) 9-(5 Figure Noise mobile is NF ,/101.381 ofconstant Boltzmann theisk

290K)T (assuming 174

mobile theofdensity spectral noise theis Where1

_

23-

1

KJ

NFdBmNFTkN

N

RWNE

LWNTxPwBS

rf

rf

DL

N

jj

jobjrf

⋅

=+−=+⋅=

−

⋅⋅⋅=

∑ =

η

υ


• Part of the downlink power has to be allocated for the common channels that are transmitted independently of the traffic channels

Downlink Common Channels

Downlink common channels

Relative to CPICH Activity Average Power allocation with 20W max Power

CPICH 0 dB 100% 2.0 W

P-SCH -3 dB 10% 0.1 W

S-SCH -3 dB 10% 0.1 W

P-CCPCH -5 dB 90% 0.6 W

PICH -8 dB 100%¹ 0.3 W

AICH -8 dB 100%¹ 0.3 W

S-CCPCH 0 dB² 10%³ 0.2 W

Total Common channels Power

3.6 W

Remaining power for traffic channels

20-3.6 = 16.4 W

Almost 50% is for CPICH


¹ Worst case; ² Depends on the FACH bit rate; ³ Depends on PCH and FACH traffic

Relation of Uplink and Downlink Load

• Downlink load is always higher than uplink load due to:

– asymmetry in user traffic– different Eb/No values in

uplink and downlink– orthogonality in downlink– overhead due to soft-

handover

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50

UL Load [%]

DL

Load

[%]

Increasing asymmetry



• As the demand for downlink capacity increases, there are several different ways of increasing capacity. The most common ways are adding more frequencies and power amplifiers, and introducing transmit diversity

• Upgrading capacity in the ways just mentioned is of course dependant on the base station equipment being able to handle it. It is reasonable to assume that as the capacity demand increases, the equipment vendors will produce equipment that can handle it

• Assume an initial base station configuration of one 20W power amplifier per sector, one carrier per sector and three sectors per site. This is called the baseline configuration, and has a baseline capacity

• The first step to upgrade the capacity is to add a second frequency. This gives a capacity increase of 80%. The reason why the increase is not 100% is that the power amplifier only can deliver 20W, which has to be split between the two frequencies, making the output 10W per carrier.

• The second step could be to add a second 20W power amplifier (restoring the power per frequency to 20W) and introduce transmit diversity.

• With these two upgrades the capacity now is 180% compared to the baseline. Adding a third frequency would decrease the output power to 13 W per carrier, but the extra carrier would still mean a capacity increase of 290% compared to the baseline

• If there are no more frequencies available, changing the power amplifiers from two 20W to two 40W will give a modest capacity increase, making the increase compared to baseline 320%. Adding a fourth frequency and at the same time changing out the two 20W power amplifiers to two 40W amplifiers, if that has not been done before, gives a capacity increase 460% compared to the baseline.

Capacity Limited Downlink

• Upgrading the power amplifier restores the power per frequency to 20W, the same as the baseline case. With the stronger PA’s there is power to add a fifth and a sixth carrier. This would give capacities of 550% respectively 680% compared to the baseline

• Using two PA’s means that no modification to the antenna system is required. Adding a third PA means that either a combiner, or an extra antenna needs to be used. A combiner typically has a 3dB insertion loss, offsetting the gain achieved

• Adding a third antenna is complicated from a site-engineering point of view. An extra feeder cable is needed, and adding an extra antenna could be difficult since it means renegotiating the agreement with the house owner.

• With a third PA the 6 frequencies is transmitting at 20W, giving a 740% increase gain compared to the baseline capacity.

Capacity Limited Downlink


Example upgrade path

Typical Pathlosses for different Bearer Services


Low Data Scenario

140,00

145,00

150,00

155,00

160,00

165,00

0 10 20 30 40 50 60 70 80

UL Load

Path

loss

[dB

] Speech 12,2k UL PathlossRT Data 14k UL PathlossRT Data 64k UL PathlossNRT Data 144k UL PathlossNRT Data 384k UL PathlossDL Pathloss

Low Asymmetry Scenario

bette

r cov

erag

e

Capacity is downlink limited

Coverage is uplink limited

Part VIIIWCDMA Link Budget


WCDMA Link Budget


WCDMA Link Budget – Cell Sizes•Output of Link Budget is MAPL (Maximum Allowed Path Loss) based on different:

- Clutter types (Dense Urban, Urban, Sub-Urban, Rural)- Services (AMR, PS64, CS64, PS128, PS384,…)- Indoor/Outdoor- Area Location Probability- Mobile speed: Pedestrian/Vehicular

•Given an area to be covered (Km²) the cell count has to be performed based on Cell Area ( Cell Radius)•Cell Radius can be calculated using Propagation models (Cost231, Hokumura-Hata, Walfish-Ikegami,…)•The models need as input:

•MAPL•UE antenna height•NodeB antenna height•Frequency•Clutter correction factors


rr = Cell Radius

Surface of a tri-sectorial cell :

Number of Sites = Number of Cells /3

Intersite Distance = 1.5*r

2

233 rACell =

Example:r = 0.409 km Acell = 0.432 km2

Stotal = 100 km²Number of Tri-secotrial sites = 100/0.432 ≈ 230

WCDMA Link Budget – Cell Count


Part IXCoverage-Capacity

enhancement



Coverage Improvement Alternatives

• Mast head amplifier– basic solution for optimized uplink performance– compensates feeder cable loss– supported by Nokia's base stations– can be used together with Smart Radio Concept

• 6 sectored site– utilizing narrowbeam antennas – ~ 2 dB better antenna gain than in 3

sectored site

• Nokia Smart Radio Concept, SRC– 4-branch uplink diversity


Capacity Improvement Alternatives

• 6 sectored site– ~ 80% capacity gain compared to 3

sectors (not 100% due to inter-sector interference)

• More carriers (frequencies) per sector– doubling the amount of carriers with

power splitting gives roughly 60% more capacity

• Smart Radio Concept– transmit diversity

Smart Radio Concept


Received signal powerUplink coverage

– 4-branch diversity reception per sector– Maximal ratio baseband combining of 4

uplink signals forms a beam

Combinedreceived signal

WCDMATransceiverWCDMA

Transceiver

RX + TXRXRX

RX+ TX

Downlink capacity upgrade– Upgrade transmit diversity when needed

0 0.5 1 1.5 2 2.5-15

-10

-5

0

5

10dB

Seconds, 3km/h

SRC Rx diversity

144 kbps Coverage / Capacity in Macro CellsMax. allowed path loss [dB]


145

150

155

160

165

170

100 200 300 400 500 600 700 800 900 1000110012001300Load per sector [kbps]

Better coverage

Downlink load curve

Uplink load curve with RX diversity for 144 kbps

Capacity isdownlink limited

Coverage isuplink limited

Nokia Smart Radio ConceptPhase 1: Increase Uplink Coverage

Max. allowed path loss [dB]


145

150

155

160

165

170


Uplink load curve with SRC

Uplink load curve without SRC

2.5-3.0 dB coverage improvement with SRC

Nokia Smart Radio ConceptPhase 2: Increase Downlink Capacity

Max. allowed path loss [dB]


145

150

155

160

165

170


Downlink 20W

no diversity

Downlink with TX diversity, 20W per

branch

70% increase in capacity

Coverage : 30 % less sites with SRC

Sites / km2

0

0.05

0.1

0.15

0.2

0.25

0.3

3-sector (rx div) 3-sector (SRC)

2.5 - 3.0 dB gaincorresponds to 30% less sites with SRC

2.5 - 3.0 dB gaincorresponds to 30% less sites with SRC


Capacity Upgrade with Smart Radio Concept• No changes to antennas or antenna cables • All these capacity upgrades within one Ultrasite cabinet


0

50

100

150

200

250

300

350

Speech Erlang per site

20W 2x10W + 2x10WDownlink power per sector

Add tx diversity +take 2nd frequency

into use

Add tx diversity +take 2nd frequency

into use

Cost / Erlang isdecreasing with

capacity upgrades

Cost / Erlang isdecreasing with

capacity upgrades

Capacity OptimisationThe impact of MHA, SRC & 6 -sector site 3G Radio Network Planning case study

Assumptions:•The geographic area under study is defined by the suburban area of London •The site's location was given, antennas´ directions are the same as the DCS network. Two antenna type has been used, 60 and 90 degrees horizontal opening•1800MHz measurements provided. Assumption that narrow band 1800MHz propagation is representative of wideband 2GHz propagation•15dB of building penetration loss included in the link budget for Indoor Coverage. •Multiple simulation runs. MS positions and slow fading changed for each run


Area under Investigation

Suburban area of London12km by 11kmIntended to be representative of suburban areas across the UK

Morphology analysis

Morphology Percentage AreaSuburban 65.2%

Open/Fields 13.7%Open in Urban 10.1%

Industrial 6.3%Roads in Urban 2.2%

Forest 2.0%Urban 0.5%Water 0.1%


Radio Network Configuration


Parameter Value Max. transmit power 43dBm Max. power per link not limited Min. transmit power per link not limited CPICH power 30dBm Common channel power 30dBm Cable/connector loss 3dB Soft handover window 5dB RF carriers available 1 Slow fading standard dev. 8dB Maximum uplink load 50%

51 sites (3 sector)

existing 1G and 2G sites, plussites to be acquired prior to 3G

Link level simulations used to define Eb/No requirements, SHO Gain

Vehicular A channel assumed

Parameter Assumptions

Antenna Configuration1G and 2G antenna list

60° antenna x 5685° antenna x 97

3G antenna list60° antenna x 5690° antenna x 97

Differences in elec. tilt compensated with mech. tilt


Antenna Type HorizontalBeamwidth

VerticalBeamwidth

ElectricalDowntilt

Antenna Gain

741415 60° 7° 0° 18dBiCS72138 90° 7° 2° 16.5dBi

741415 CS72138

Traffic ModelingPriority placed on modeling traffic services separately

12.2kbps speech64kbps data144kbps data

Symetric data services

Uniform distribution of mobile terminals

System loaded to maximum capability

fixed uplink load limitfixed BTS power capability

Link level simulations used to define Eb/No requirements, SHO Gain

ServiceParameter 12.2 kbps

voice64 kbps data 144 kbps data

Max. transmit power 21 dBm 21 dBm 21 dBmMin. transmit power -50 dBm -50 dBm -50 dBmAntenna height 1.5 m 1.5 m 1.5 mAntenna gain 0 dBi 0 dBi 2 dBiBody loss 3 dB 0 dB 0 dBUplink bit rate 12.2 kbps 64 kbps 144 kbpsDownlink bit rate 12.2 kbps 64 kbps 144 kbpsUplink activity factor 0.67 1 1Downlink activity factor 0.67 1 1Mobile speed 50 km/hr 3 km/hr 3 km/hr

12.2kbps speech 15000 ~5400

64kbps data 5000 ~1100

144kbps data 1500 ~500

Distrib. Supp.

MS Numbers


Benchmark ResultsMHA, SRC, 6 Sector not included

Only coverage and capacity presented here


CapacitiesService Envir. network per cell

Outdoor 5074 33.212.2kbpsSpeech Indoor 5336 34.9

Outdoor 966 6.364kbpsData Indoor 1100 7.2

Outdoor 470 3.1144kbpsData Indoor 501 3.3

Uplink limited

Uplink limited

Number of 12.2kbps speech users0 30 60

100

Perc

enta

ge o

f Cel

ls

12

6

0

Num

ber o

f Cel

ls

0

Depends upon polygon

Envir. Service of theProbe Mobile

Mean

Speech 99.8364kbps Data 98.54

Outdoor

144bps Data 96.74Speech 88.05

64kbps Data 70.05Indoor

144bps Data 59.71

Impact of MHAMHA introduced at all sitesImproves uplink power budget


Remains approximately the sameuplink and downlink approximately balanced

ImprovedExample

indoor speech: 88 93%indoor 64kbps data: 70 79%indoor 144kbps data: 60 71%

Trend of results as expected

Impact of SRC (rx only)2 scenarios

SRC introduced at all sitesSRC introduced at TACS sites only

Reduces uplink Eb/No target

Improved

speech by 9%64kbps data by 11%144kbps data by 30%

Becomes limited by BTS tx power

Improved

indoor speech: 88 92%indoor 64kbps data: 70 77%indoor 144kbps data: 60 68%

Remains uplink limitedObservations:

Once downlink limited, soft handover window has great impact upon capacity

Introducing SRC at TACS sites only, increases capacity of surrounding sites


Impact of SRC (rx & tx)

Tx and Rx SRC introduced at all sitesReduces uplink and downlink Eb/No targets

Further Improved

Example: outdoor speechno SRC 5000 usersrx SRC 5800 users (+15%)rx&tx SRC 7500 users (+49%)

Tx SRC offers no coverage improvement over Rx SRCCoverage remains uplink limited


Impact of 6 Sectors


DoubledExample, outdoor

speech, 2500 5100 users64kbps data, 440 950 users144kbps data, 230 450 users

2 scenarios6 Sector introduced at all sites6 Sector introduced at TACS sites only

33º beam width antennas increased gain

ImprovedExample,

indoor speech: 85 93%indoor 64kbps data: 65 80 %indoor 144kbps data: 50 70 %

Not true in this case due to antenna pattern selected:reduced SHO and inter-cell interference

Usual message for 6S:capacity improves by less than a factor of 2 due to increased SHO & inter-cell interference

Part XWCDMA/GSM

Co-siting issues


Antenna System Co-siting


• GSM 900 / GSM 1800 shared antenna lines by diplexers/triplexers

• GSM 900 / GSM 1800/WCDMA multi band antennas

Antennas: WCDMA/GSM Co-site

Shared antenna lines• GSM 900 / GSM 1800 /

WCDMA triplexers

Shared antennas• Dual Band GSM 900 /

WCDMA • Dual Band GSM

1800/WCDMA• Triple Band

900/1800/WCDMA

Mast Head Amplifiers• Triplexer supports MHA in one

branch• Additional MHAs to be

equipped with direct DC feed

Antenna 1:

GSM 900 / 1800

Dual Band X-pol

Antenna 2:

WCDMA X-pol

GSM 900 / GSM 1800 / WCDMA Triplexer-1

WCDMA

MHA

WCDMA

MHA

WCDMA

BTS with Bias-TsGSM 900

BTS

GSM 1800

BTS

GSM 900 / GSM 1800 / WCDMA Triplexer-2

3 sector si te:

GSM 900/1800 antennas: 3 pcs

WCDMA antennas: 3 pcs

WCDMA MHAs: 6 pcs

Triplexers: 6 pcs

Feederlines: 6 pcs


Upgrades to Current GSM Antennas

Upgrade :space + polarizationdiversity

Space diversity improves performance 0.5..1.0 dB compared

to single radome. The gain of 2.5 dB

assumes single radome.

Space diversity improves performance 0.5..1.0 dB compared

to single radome. The gain of 2.5 dB

assumes single radome.

Current :space diversity


Upgrade:2 x polarization diversity withinone radome

300 mm

Antennas can be shared with GSM

Current :polarization diversity

1300 mm

150 mm

Example: common feeders, separate antennas


• GSM 900/1800 BTS & WCDMA BTS• Triplexers

– common feeders• Separate antennas

– 900/1800 MHz dual-band– 2 GHz

DPX

DPX

WCDMABTS

GSMBTS

Iub

Abis/IubTo/FromBSC/RNC

SiteSupportSystem

Triplexer

Triplexer

TPX

Power

Nokia Base Stations and Co-SitingAir-interface issues

• WCDMA - WCDMA Co-Siting– This has been taken into account in 3GPP Air Interface Specifications– Nokia WCDMA base station products are compliant with 3GPP

• WCDMA - GSM900 Co-Siting– This has been taken into account with Nokia's WCDMA and GSM900

base station design • WCDMA - GSM1800 Co-Siting

– This is as with GSM900– If GSM1800 Transmitter Frequency separation within same sector is

more than 57 MHz( bottom channels) or 40 MHz (top channels), extra transmitter filtering (~10 dB) may be required in GSM1800 BTS

• Note: 30 dB Minimum Coupling Loss (MCL) assumed between antennas


Co-Siting with other manufacturersAir-interface issues

• WCDMA Co-Siting with other manufacturers' equipment

– theoretical worst case requires 50 dB extra isolation in GSM BTS

– in practice this much will not be needed– Nokia can provide assistance with co-siting

issues• Note: 30 dB Minimum Coupling Loss (MCL)

assumed between antennas


WCDMA - GSM Interference Outline

• Spurious emissions• Nonlinear distortion • Specifications and isolation requirements• Interference mitigation methods• Co-located sites


• Site and equipment sharing is an important issue to cut costs down and to guarantee proper function of the networks.

• Common • base station mechanics• site support• transmission• antennas and feeders• site construction• network management

• By proper site design (antenna installation etc.) interference coupling between systems can be reduced and unreasonable degradation of service due to co-sited installations avoided.

• Co-siting preferred to avoid high path loss differences between ownand neighbour systems.

WCDMA - GSM Interference Outline


Spurious emissions

• ITU-R definition of Spurious Emission (ITU-R: 329-7_ww7.doc):– Spurious Emission: Emission on a frequency or frequencies which

are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmissions of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products, but exclude out-of-band emissions.

• Normally the intermodulation distortion (IMD) is handled separately due to its importance.

• Spurious signals can be coupled by– radiation– conduction– combination of radiation and conduction


Nonlinear system• Nonlinear system transfer function can be expressed as a series expansion

• In the case of one input frequency, vin = cos ω1t, output will consist of harmonics, mω1

– Fundamental (m = 1) frequency is the desired one.– If m > 1, there are higher order harmonics in output => harmonic

distortion.– Can be generated both inside an offender or a victim system.

• In the case of two input frequencies, vin = cos ω1t + cos ω2t , output will consist of harmonics mω1 + nω2, where n and m are positive or negative integers.

– Intermodulation is a process generating an output signal containing frequency components not present in the input signal and it is called intermodulation distortion (IMD).

– Most harmful are 3rd order (|m| + |n| = 3) products.– Can be generated both inside an offender or a victim system.

x y = a0 + a1x + a2x2 + a3x3 + ...System


Nonlinear components

• Nonlinearities of active components like amplifiers under normaloperation.

• Nonlinearities of passive components– Antennas– Feeders– Connectors

• Antenna mismatching– Reflected wave can cause IMD in the power amplifier.

• Damaged feeders => mismatching• Loose connectors => mismatching, reflections and rectification.


Active nonlinear distortion


• Active nonlinear distortion is generated in nonlinearities of active components like amplifiers and modulators

• The nonlinearity effect is especially strong in power amplifiers if they are driven to saturation.

• Intermodulation levels of the amplifiers can be decreased by backing-off of them.

Desired signalslope = 1

3rd orderIMDslope = 3

3rd order intercept point• The amplitude of the 3rd order product

increases 3 dB compared to the fundamental frequencies due to x3 term of it.

• Active IMD generated inside an offender BTS can be removed by BTS TX filtering.

Passive nonlinear distortion

• Passive nonlinear distortion is generated in nonlinearities of passive components like connectors, antennas and feeders.

• Contact and material nonlinearities– Loose connectors– Oxidation of joints– Cracks in materials– Electron tunneling through layers – Nonlinear resistivity of materials– B/H nonlinear hysteresis

• Levels normally lower than in active IMD.• Aging of the components increases IMD• Can NOT be filtered out in BTS TX.

I

V

B

H


Harmonic distortion

• Harmonic distortion can be a problem in the case of co-siting of GSM900 and WCDMA.

• GSM900 DL frequencies are 935 - 960 MHz and second harmonics may fall into the WCDMA TDD band and into the lower end of the FDD band.

• 2nd harmonics can be filtered out at the output of GSM900 BTS.

2nd harmonics


GSM900935 - 960 MHz

fGSM = 950 - 960 MHz

WCDMATDD

WCDMA FDD1920 - 1980

...

1900 -1920 MHz

IMD3 from GSM1800 DL to WCDMA UL

f1 f2fIM3

fIM3 = 2f2 - f1

• GSM1800 IM3 products are hitting into the WCDMA FDD UL RX band if

• 1862.6 ≤ f2 ≤ 1879.8 MHz• 1805.2 ≤ f1 ≤ 1839.6 MHz

X dBc

• For active elements IMproducts levels are higherthan IM products producedby passive components• Typical IM3 suppressionvalues for power amplifiers are -30 … -50 dBc depending on frequencyspacing and offset• Typical values for passiveelements are -100 … -160 dBc

GSM1800UL

GSM1800DL

WCDMAUL

WCDMADL


1710 - 1785 MHz 1805 - 1880 MHz40 MHz1920 - 1980 MHz 2110 - 2170 MHz

Nonlinear distortion conclusions• Second harmonics from the GSM900 system may fall into the WCDMA TDD

band.• Intermodulation can be a problem if an operator has a splitted GSM1800 band or

in multioperator systems.• The most harmful intermodulation products are 3rd order products which may fall

into the WCDMA RX band:

fIM3 = 2f1,2 — f2,1

• IM products can be avoided by proper frequency planning in GSM. • fIM3 is hitting into the WCDMA FDD RX band (1920 - 1980 MHz) if GSM1800

channels are from 512 to 684 (f2) and from 799 to 885 (f1).• Active intermodulation products can be filtered out in GSM1800 BTS TX

– IM products generated inside a WCDMA receiver cannot be filtered out.• Passive IM products can not be filtered out in BTS TX if they are generated in

feeder lines and connectors after the filtering unit of BTS.• Some aging problems may be avoided by installation, site administration and

maintenance recommendations.


RF Specifications

• GSM 05.05-8.7.1, WCDMA TS 25.104-3.5.0• Two main reasons to isolate GSM and WCDMA

– Blocking– Sensitivity

Transmitter Frequency[MHz]

Level[dBm] / [MHz]

Parameter affected Required[dBm] / MHz

Requiredisolation [dB]

GSMspurious

1920 – 1980(FDD UL)

−96 / 0.1-80 / 4.0

UMTS BTSsensitivity

< −108 / 4.0(Noise floor)

28

GSMmain

1805 −1880

+40 / 0.2Typical

UMTS BTSblocking

< −15 / CW(Specifications)

55

UMTSspurious

1710 −1785

−98 / 0.1−95 / 0.2

GSM BTSsensitivity

< −110 / 0.2(Typical)

15

UMTSmain

2110 – 2170(FDD DL)

+43 / 4.0Typical

GSM BTSblocking

0(Specifications)

43


Interference mitigation methods

• Means to achieve the required isolation– RF-methods

• Tighter filtering of the GSM BTS TX signal• Proper frequency planning in GSM• Di- or triplexer in case of feeder and antenna sharing between

different systems • By proper antenna selection and placing

– Baseband methods• Interference cancellation receivers• If the interferer is known its effect can be removed easily

– Combined RF and baseband methods


Antenna isolation measurements

• Measurements performed in an anechoic room in a GSM1800 band with a HP8753/D network analyzer.

• According to the most common definition the far field assumption is valid if

where D is the largest dimension of an antenna, λ is wavelength and df

is the distance from antenna.• The far field assumption is not valid => measurements needed. • For a typical GSM1800 antenna dimensions (D ≈ 1 m) df ≈ 13 m.• Let's assume coupling loss of 65 dB from the near field to the far field =>

– Extra 10 dB means therefore about 30 m distance by deploying a free space model from d0 = 10 m.

λλ

>>= DdDd ff , and ,2 2


Isolation measurements Antennas and configurations

AntennaHorizontalbeamwidth Gain Polarisation Frequency band

Vert. Pol A 65º 18 dBi Vertically linear 1710 – 1880 MHzB 90º 16 dBi Vertically linear 1710 – 1880 MHzC 90º 17.5 dBi Vertically linear 1710 – 1880 MHz

Dual. Pol D 90º 16 dBi +/- 45º dual pol. 1710 – 1880 MHz

V (Vertical)

dd

III (180°) IV (Horizontal)

d

II (120°)

120°d

I (90°)

dd


1TSG-RAN Working Group 4 (Radio) Meeting #8 TSGR4#8(99)631

Sophia Antipolis, France26-29 October 1999Source: Allgon

Antenna isolation measurementsSetup Antenna d [mm] / Min

isolation [dB]d [mm] / Maxisolation [dB]

I A 250 / 50 850 / 63B 250 / 46 975 / 59C 250 / 54 950 / 62D, Co-polar 200 / 46 1250 / 59D, Cross-polar 200 / 49 1000 / 58

II A Same mast / 49 1050 / 66B Same mast / 38 1100 / 66C Same mast / 53 1150 / 68D, Co-polar Same mast / 38 1100 / 65D, Cross-polar Same mast / 43 1050 / 63

Setup Antenna d [mm] / Minisolation [dB]

d [mm] / Maxisolation [dB]

I A 250 / 50 850 / 63B 250 / 46 975 / 59C 250 / 54 950 / 62D, Co-polar 200 / 46 1250 / 59D, Cross-polar 200 / 49 1000 / 58

II A Same mast / 49 1050 / 66B Same mast / 38 1100 / 66C Same mast / 53 1150 / 68D, Co-polar Same mast / 38 1100 / 65D, Cross-polar Same mast / 43 1050 / 63

I (90°)

dd

II (120°)

120°d




III A Same mast / 52 750 / 71

B Same mast / 49 1300 / 69C Same mast / 52 1150 / 76D, Co-polar Same mast / 38 1250 / 62D, Cross-polar Same mast / 53 1250 / 62

IV A 250 / 37 6000 / 57B 250 / 27 6000 / 52C 250 / 34 6000 / 48D, Co-polar 250 / 33 4250 / 53D, Cross-polar 250 / 36 6000 / 57

d

III (180°)

IV (Horizontal)

d





V A 2250 / 50 6000 / 70B 2250 / 55 5500 / 69C 2250 / 61 6000 / 66D, Co-polar 1500 / 42 6000 / 61D, Cross-polar 1500 / 44 5500 / 65V (Vertical)

d




• Measurements performed in a more realistic environment by Nokia.• The used antennas are listed in the table below

Band Manufacturer Model No HorizontalBeamwidth

Polarisation VerticalBeamwidth

Gain ElectricalDowntilt

UMTS Racal UMTSXP/65/17.7/2 65 deg. X-polar 7 deg 17.7dB 2 degGSM1800 CSA PCNV065-13-0B 65 deg. X-polar 7 deg 18 dBi 0 degGSM1800 CSA PCNV065-13-0B 65 deg. X-polar 7 deg 18 dBi 0 degGSM1800 CSA PCNV085-13-0B 85 deg. X-polar 7 deg 16 dBi 0 degGSM1800 CSA PCNA115-19-0B 115 deg. Vertical 5 deg 17dBi 0 deg

• Horizontal, vertical and combined displacement configurations measured.• Rooftop, face and tower mounted measurements.• Both co- and cross-polar feed used.



• Measured frequencies from 1710 to 1980 MHz and results collected from 1900, 1950 and 1980 MHz.

• Measurement corresponds spurious emissions attenuation from the

GSM1800 band into the WCDMA band.


output input

Antenna A (fixed) Network Analyser Antenna B

Figure 3. Equipment set up

Antenna isolation measurements: Horizontal


Antenna A(fixed)

Antenna BUMTS

horizontalseparationdistance

Front View

direction of radiation

2000mm

1000mm

400mm

Side View

650mm

Figure 5. Sketch of measurement configuration


GSM1800 65 deg to UMTS 65 degHorizontal co-polar measurements

40.00

45.00

50.00

55.00

60.00

65.00

70.00

75.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

1...

Distance (m)

Isol

atio

n (d

B) 1900MHz

1950MHz1980MHz

50dB marker



GSM1800 85 deg to UMTS 65 degHorizontal co-polar measurements

30.00

35.00

40.00

45.00

50.00

55.00

60.00

65.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

Distance (m)

Isol

atio

n (d

B)

1900MHz1950MHz1980MHz

50dB marker



GSM1800 115 deg to UMTS 65 degHorizontal measurements

30.00

35.00

40.00

45.00

50.00

55.00

60.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

Distance (m)

Isol

atio

n (d

B)


50dB marker


Antenna isolation measurements: Face


Antenna AGSM1800

Antenna BUMTS

1m 5m


300mm


2000mm

1000mm

400mm

Side View

650mm


Front View

Antenna isolation measurements: Face

Face mounting GSM1800 85 deg to UMTS 65 deg - Co-polar

70.00

75.00

80.00

85.00

0.00 1.00 2.00 3.00 4.00 5.00



Antenna isolation measurements: Vertical



10m

Antenna BUMTS

Antenna AGSM1800

(fixed)

Antenna isolation measurements: Vertical

Noise Floor

GSM1800 115 deg to UMTS 65 deg

50.00

55.00

60.00

65.00

70.00

75.00

80.00

85.00

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Distance (m)

Isol

atio

n (d

B)


Noise Floor


Antenna measurement conclusions

• According to the measurements it's easy to find a configuration,which provides isolation of 30 - 60 dB.

• Lowest isolation (27 dB) was measured in an anechoic room antennas horizontally displaced 0.25 m

– with 6 m distance isolation was already about 50 - 55 dB.• Highest isolation values were measured with the face mounted

antenna and the isolation was more than 70 dB.• In Allgon's measurements both antennas were for GSM1800 and in

Nokia's measurements for GSM1800 and WCDMA. – There is also attenuation between GSM1800 and WCDMA due to

frequency difference of them => isolation figures are higher forthe spurious emissions.


Horizontal Separation : XPol 900 65° _ XPol UMTS(824-960) (1710-2170)

Isolation 800/900 - UMTS


Isolation 800/900 - UMTSHorizontal Separation : XPol 900 90° _ XPol UMTS

(824-960) (1710-2170)


Vertical Separation : XPol 900 65° _ XPol UMTS(824-960) (1710-2170)



Isolation 800/900 - UMTSSeparation by 120° : XPol 900 65° _ XPol UMTS

(824-960) (1710-2170)



(824-960) (1710-2170)



(1710-1990) (1710-2170)



(1710-1880) (1710-2170)



(1710-1990) (1710-2170)



(1710-1880) (1710-2170)


Isolation Dualband GSM 900/1800 - UMTSHorizontal Separation : XXPol 900/1800 65°/65° _ XPol UMTS

(870-960/1710-1880) (1710-2170)


Isolation Dualband GSM 900/1800 - UMTSVertical Separation : XXPol 900/1800 65°/65° _ XPol UMTS

(870-960/1710-1880) (1710-2170)


Isolation UMTS - UMTSHorizontal Separation : XPol UMTS 65° _ XPol UMTS

(1710-2170) (1710-2170)



Vertical Separation : XPol UMTS 65° _ XPol UMTS(1710-2170) (1710-2170)

Isolation UMTS - UMTS

Isolation UMTS - UMTSSeparation by 120°: XPol UMTS 65° _ XPol UMTS

(1710-2170) (1710-2170)


Part XIWCDMA Optimization


Network Optimization ProcessObjective: To optimize the outdoor part of the 3G network, this done cluster wise, as they are being integrated.

The main elements for this process are:1.Pre-optimisationsurvey2.Network check3.Initial drive test, baseline4.Pre-Launch optimization

•Cluster tuning until break-out point is reached•Ready for network acceptance & reporting


Pre Launch Optimization-Overview


Pre Launch Optimization-Process


Optimization-Overview


Optimization-Overview Block A


Optimization-Overview Block B


Optimization-Overview Block C


Optimisation - required performance


• Examples of performance metrics– Area of service availability or coverage performance– Average FER, BLER– Access failures including paging and SMS– MOC/MOT Call Setup Failures– Dropped call performance– Handover percentage (Soft/Hard)– Ec/Io&RSCP performance

• UMTS Bearer Service Attributes– Maximum/Average bitrate (kbps)– Residual bit error ratio– Transfer Delay– Guaranteed bitrate (kbps)

Key Performance Indicators, KPI• KPIs are a set of selected indicators which are used for measuring the

current network performance and trends.• KPIs highlight the key factors of network monitoring and warn in time of

potential problems. KPIs are also used to prioritise the corrective actions.• KPIs can be defined for circuit switched and packet switched traffic

separately and be measured by field measurement systems and Nokia NetActTM network management system.

• An example set of KPIs– RRC Setup Complete Ratio– RAB Setup Complete Ratio– RAB Active Complete Ratio– Call Setup Success Ratio– Call Drop Rate– Softer/Soft Handover Fail Ratio


WCDMA RAN Optimisation


Network Management• Nokia NetActTM for 3G• Field Tool Server

RAN Optimisation• pre-defined procedures• semi / full automated

configuration

Start

WindowAddChange 1 stepsize

WindrowDropChange 1 stepsize

CompThresholdChange 1 stepsize

DropTimerChange 1 stepsize

NMS: Collectnetwork

performance data

Evaluate KPI 'HO Overhead'.

OK ?

Evaluate allnetwork KPIs.

OK ?

Yes

Go to relevantoptimisation flow-chart

No

End

Yes

No

measurements

KPIs, counters

air-interface

Field Tool

WCDMA RAN

KPIs, measurements

Configuration

WCDMA Field Tool


Phase 1

Phase 2

Data Logging Tool

Post Processing Tool

Field Tool Server• map data• network configuration

information

•Measurement data withlocation and timestamp

•Measurement data withlocation and timestamp

•File & remote IP basedinterface

• connection to NMS

• Map data• Network configuration

information

Part XIIRadio Resource

Management


Radio Resource Management


RRM Control Processes


WCDMA Radio Resource Management: Logical Model

• AC Admission Control

• LC Load Control

• PS Packet Scheduler

• RM Resource Manager

• PC Power Control

• HC HO ControlPC

HCConnection based functions

LC

ACNetwork based functions

PS

RM


RRM control processes• Admission control:

–Performs the admission control for new bearers to enter/leave the network.

–Predicts the interference caused by the bearer and checks whether there is room for it.

–Power allocation• Packet Scheduler

–Scheduling packets to the radio interface (UL/DL)

• Load Control:–Takes care of radio network stability–Gathers interference information and produces

a load vector• Resource manager

–Manages the physical resources of RAN and maintains the code allocation


RRM control processes• Power Control

–Closed loop PC compares the measured SIR with SIR-target and accordingly transmits an up/down PC command at 0.667 ms interval

–Open loop PC estimates the needed power based on pathloss + interference measurements (RACH).

–Outer loop PC sets the SIR target for the fast closed loop PC

• Handover Control–Soft (intra-frequency) handovers: softer

between cells within one BS, intra-RNC soft, inter-RNC soft

–Inter-frequency (hard) handovers: Intra-BS, Intra-RNC, Inter-RNC (-MSC)

–Inter-RAT handovers: WCDMA <-> GSM 265


Power ControlPower Control loops in WCDMA

RNCMS BTS

Open Loop Power Control (Initial Access)

Closed Loop Power Control



Power Control Loops


• Effective power control is essential in WCDMA due to frequency re-use factor of one (in ideal case)

• Closed loop e.q. Fast power control– Makes Eb/No requirements lower– Equalizes received powers at BTS in uplink (avoids near-far

effect)– Introduces interference peaks in the transmission

• Open loop power control for initial power setting of the UE• Outer PC loop at a slower rate, across the Iub interface in

uplink– At a much slower rate, across the Iub interface in uplink– Adjusts the SIR target to achieve a target BLER– Also similar outer loop power control in MS– There is also similar outer loop power control in UE

Power Control & Diversity

• At low UE speed, power control compensates the fading : fairly constant receive power and Tx power with high variations

• With diversity the variations in Tx power is less• At UE speed >100kmph fast power control cannot follow

the fast fading, therefore diversity helps keep receive power level more or less constant

• In the UL Tx affects adjacent cell interference and Rx power affects interference within the cell.


Admission Control & Packet Scheduler

• AC handles new incoming traffic to the RAN by –estimating the total load caused by adding a new

RAB in uplink and downlink –and decides whether or not this can be admitted.

• AC also sets :–initial DL transmission power for the channel–the power control range as well as many other

parameters, e.g. Transport Format Set. • PS handles all the NRT data connections. PS is

determining the time a packet is sent and which bit rate is used.


• The key function of AC and PS is to maximize capacity (throughput) by estimating the load and to fill the system up to maximum loading while still ensuring the required quality of service for RT traffic.

• In uplink, the basic measured quantity indicating load is the total received power of a BS, PrxTotal

• In downlink, the basic measured quantity indicating load is the total transmitted power of a BS, PtxTotal

Admission Control & Packet Scheduler


Admission Control Uplink admission control

• In uplink the total received wideband interference power measured indicates the traffic load of the radio resources .

• The fundamental criteria of evaluation is based on

• Ithreshold indicates the traffic load of the radio resources • In uplink, the total received power is the function of the

maximum interference received in the wideband spectrum.


thresholdtotal_old III <∆+

power

max planned load

max planned power

?Itotal_old

Ithreshold

∆I =

load

Admission Control Uplink admission control

TRHO_threshold

Prx_target

Prx_target_BS

UL interference power

Load

Planned load area

Marginal load area

planned uplink interference power

Prx_offset


Prx_target defines the optimal operating point of the cell interference power, up to which the AC of the RNC can operate.

Admission Control Downlink admission control

TRHO_threshold

Ptx_target

Ptx_target_BS

DL transmission power

Load

Planned load area

Marginal load area

planned Downlink interference: carrier transmission power

Ptx_offset


Downlink power increase estimation is done for non-controllable load just like UL power increase.

Packet Scheduler

• Packet scheduler is a general feature, which takes care of scheduling radio resources for NRT radio access bearers for bothuplink and downlink.

• The packet access procedure in WCDMA should keep the interference caused to other users as small as possible.

• Packet access is implemented for both dedicated (DCH) and common control transport channels (RACH/FACH).

• There are three scenarios for WCDMA packet access:

• infrequent transmission of short packets,• frequent transmission of short packets (RACH/FACH)• transmission of long packets (DCH)

• Packet scheduler makes the decision of the used channel type fordownlink direction. For uplink direction the decision of the used channel type is made by UE


Packet Scheduler Capacity Division

• The proportion between RT and NRT traffic varies all the time• It is characteristics for RT traffic that the load caused by it cannot be

controlled in efficient way.• The available capacity, which is not used for non-controllable load,

can be used for NRT radio access bearers on best effort basis.


load

time

planned target loadfree capacity, which can beallocated for controllableload on best effort basis

non-controllable load

Packet Scheduler Load Decrease Example


Packet Scheduling Principle


Load ControlCapacity


Overload area

Load TargetOverload Margin

Pow

er

Time

Estimated capacity for NRT traffic.

Measured load causedby noncontrollable load

• The traffic can be divided into two groups– Real Time (RT)– Non-Real Time (NRT)

• THUS some portion of capacity must be reserved for the RT traffic for mobility purposes all the time. The proportion between RT and NRT traffic varies all the time.

Load Control Definition of Non-controllable traffic

• Since it is not enough to divide the load to RT and NRT one must take into account the interference coming from surrounding cells.

Traffic is divided into controllable and non-controllable traffic.

Non-controllable traffic = RT users +other-cell users +noise +other NRT users which operate minimum bit rate

Controllable traffic = NRT users


Logical description of load control

• The purpose of load control is to optimize the capacity of a cell and prevent overload situation.

• Load control consists of Admission Control (AC) and Packet Scheduler (PS) algorithms, and Load Control (LC) which updates the load status of the cell based on resource measurements and estimations provided by AC and PS.

LC

AC

PS

Load change info

Load status

NRT load


Handover Control


Handover Control - WCDMA Handovers


• Supported WCDMA handovers for PS and CS services :• Soft handover

– MS simultaneously connected to many cells– Mobile Evaluated HandOver (MEHO)– Intrafrequency handover

• Hard handover– Intrafrequency hard handover

• Arises when interRNC SHO is impossible• Decision procedure is the same as SHO; MEHO and RNC

controlled• Causes temporary disconnection of the user

– Inter-frequency handover• Can be intraBS hard handover, intraRNC hard handover,

interRNC hard handover• Network Evaluated HandOver (NEHO)• Decision algorithm located in RNC

– Inter-RAT handover • Handovers between GSM and WCDMA

Softer Handover


Sector/Antenna RAKEcombining(MRC)

RNC

• Handover between cells within a BS

• softer handover is handled by BS internally

• softer handover probability about 5 - 15 %

• no extra transmissions across Iub

• basically same RAKE MRC processing as for multipath/antenna diversity (BS / MS). More RAKE fingers needed.

• provides additional diversity gain

• softer handover does create additional interference and needs BS PA resources

Soft handover


CNRNC

frame reliability info

frame reliability info

frame selection /duplication

Except for the TPC symbolexactly the same information(symbols) sent over air.Differential delay in order of fraction of symbol duration

• Handover between cells from different BS's

• Soft handover probability about 20 - 50 %

• Required to avoid near/far effects• Extra transmission across Iub, more

channel cards are needed

• DL/MS: Maximal ratio combining• UL/RNC: Frame selection combining• Soft handover does create additional

interference in downlink and needs BS power amplifier resources

• DL Power drifting in soft HO BSs a problem due to independent errors in uplink commands

Handover Control – IntraFrequency Handovers


Handover ControlIntraFrequency Handovers Measurements


Handover ControlIntraFrequency Measurement Reporting Events


Differences between Handovers


Benefits from Inter-System handover


Load and coverage reasons handover


Service Control


Resource Manager


• The main function of RM is to allocate logical radio resources of BS according to the channel request by the RRC layer for each radioconnection

• The RM is located in the RNC and it works in close co-operation with the AC and the PS

• The actual input for resource allocation comes from the AC /PS and RM informs the PS about the resource situation

• The RM is able to switch codes and code types for different reasons such as soft handover and defragmentation of code tree.

• Manages the BS logical resources– BS reports the available logical HW resources

• Maintains the code tree, – Allocates the DL channelization codes, UL scrambling code, UL

channelization code type• Allocates UTRAN Registration Area(URA) specific Radio Network

Temporary Identifier(RNTI) allocated for each connection and reallocated when updating URA

Resource ManagerSpreading

• Spreading = channelization and scrambling operations (producing the signal at the chip rate, i.e. spreads the signal to the wideband)

• Downlink: Scrambling code separates the cells and channelizationcode separates connection

• Uplink: Scrambling code separates the MS's, channelization code separates the DPDCHs in case of multicode

• The length of the channelization code is the spreading factor• All physical channels are spread with channelization codes, Cm(n)

and subsequently by the scrambling code, CFSCR

• The code order, m and the code number, n designates each and every channellization code in the layered orthogonal code sequences.


user data widespread data

chanellizationcode

scramblingcode

3g overview

Documents