Benefits of 3GPP WCDMA

• Higher Capacity - about 2X IS-95, 7X GSM• Ability to Send up to 384 kbps High Speed Data while Moving• (Internet, video, multimedia, etc.)• Up to 2 Mbps Throughput for Fixed Applications• 5 MHz Bandwidth is more Immune to Fading• No Accurate Base Station Synchronization Needed• Support for Hand-off To and From GSM

Differences between WCDMA & GSM

WCDMA GSM

Carrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 1–18

Power controlfrequency

1500 Hz 2 Hz or lower

Quality control Radio resourcemanagement algorithms

Network planning(frequency planning)

Frequency diversity 5 MHz bandwidth givesmultipath diversity with

Rake receiver

Frequency hopping

Packet data Load-based packetscheduling

Timeslot basedscheduling with GPRS

Downlink transmitdiversity

Supported forimproving downlink

capacity

Not supported by thestandard, but can be

applied

High bit rates

Services withDifferent quality

requirements

Efficient packet data

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 kbps 256 15 30 12–24 6–12 kbps 128 30 60 42–51 20–24 kbps 64 60 120 90 45 kbps 32 120 240 210 105 kbps 16 240 480 432 215 kbps 8 480 960 912 456 kbps 4 960 1920 1872 936 kbps

4, with 3 parallel codes

2880 5760 5616 2.3 Mbps

Half rate speechFull rate speech

128 kbps384 kbps

2 Mbps

Symbolphyb RR 2_SF

WRSymbol

(QPSK modulation)

Physical Layer Bit Rates (DL)

RRM Functionalities• LC Load Control

• AC Admission Control

• PS Packet Scheduler

• RM Resource Manager

• PC Power Control

• HC HO ControlPC

HCFor each connection/user

LC

AC

For each cell

PS

RM

Resource Manager (RM)

– Responsible for managing the logical radio resources of the RNC in co-operation with AC and PS

– On request for resources, from either AC(RT) or PS(NRT), RM allocates:

• DL spreading code• UL scrambling code

Code Type Uplink Downlink

Scrambling codes

Spreading codes

User separation Cell separation

Data & control channels from same UEUsers within one cell

Node BU

plin

k an

d D

ownl

ink

Ded

icat

ed C

hann

els

The introduction of 3G made use of uplink and downlink dedicated channels to transfer user plane and control plane data in CELL_DCH

Applicable to• All 3GPP Releases

Uplink air-interface capacity defined by maximum planned increase in uplink interferenceDownlink air-interface capacity defined by downlink transmit power capability

Cell_DCH

CS and PS services

Channel Types for User Plane Data (R99)

Node B

In R5 3G evolved to include HSDPA for transferring packet switched user plane data in the downlink direction

Applicable to• 3GPP Release 05• NSN RAS05, RAS05.1

HSDPA makes use of a downlink transmit power allocation and so has a direct impact upon downlink capacity

The resource shared between multiple HSDPA users is the HSDPA downlink transmit power

The Node B scheduler assigns timeslots & codes to specific UE to allow access to the HSDPA downlink transmit power

Upl

ink

Ded

icat

ed

Chan

nels

Cell_DCH

HSD

PA

PS services CS services continue to use R99 dedicated channels

Channel Types for User Plane Data (R5)

Node B

• 3G has further evolved to include HSUPA for transferring packet switched user plane data in the uplink direction

• Applicable to– 3GPP Release 06

– NSN RAS06, RU10

• HSUPA makes use of a uplink interference allocation and so has a direct impact upon uplink capacity

• The resource shared between multiple HSUPA users is the uplink interference

• The Node B scheduler assigns transmit power ratios to specific UE to allow a contribution towards the total increase in uplink interference

HSU

PA

Cell_DCH

HSD

PA

PS services CS services continue to use R99 dedicated channels

Channel Types for User Plane Data (R6)

3GPP Frame Structure ( need some diagram)

Physical Channels Have a Two Layer Structure:• Radio frame: 10 ms frame consisting of 15 timeslots• Timeslot: 667 usec slot consisting of a number of Symbols

Symbols are Defined as:• One Symbol Consists of a Number of Chips .• The Number of Chips per Coded Symbol is Equal to the Spread Factor of the

PhysicalChannel• Chip is a Bit at the Final Spreading Rate of 3.84 Mchips/s

3GPP Timing Options

The 3GPP System has Two Timing Modes:• Asynchronous Operation - Original Mode• GPS Synchronized - Added after HarmonizationAsynchronous Mode:• Eliminates need for GPS Satellite Receivers• Allows Operation in Tunnels, Buildings, and Subways Where Satellite

Reception is Difficult• Requires Greater Search Time, More Difficult HandoffsGPS Synchronized Mode:• Simpler, Faster Searching to Ease Soft Handoffs• Requires Base Station to Receive GPS Satellite SignalsAs

Transport vs. Physical Channels

•3GPP Supports the Concept of Multiple Services Sharing a Physical Connection

•The Concept of “Transport” Channels is used to Support these Services

•Adds an Extra Layer Where Transport Channel are Multiplexed together Prior to Transmission on a Physical Channel

Downlink Physical Channels• CPICH (Common Pilot Channel): used as a timing and frequency reference by mobile stations• P-CCPCH (Primary Common Control Physical Channel).

carries a transport channel called the Broadcast Channel (BCH). The BCH carries the system overhead information.

• S-CCPCH (Secondary Common Control Physical Chan).carries the Forward Access Channel or the Paging Channel (FACH or PCH, both of

which are transport channels). • SCH (Synchronization Channel).

To aid mobile synchronization to the network, each base station also transmits this channel.

• DPCH (Dedicated Physical Channel).carries the Dedicated Channel (DCH, which is a transport channel). The DPCH is composed of

two sub-channels: the Dedicated Physical Data Channel (DPDCH) and the Dedicated Physical Control Channel (DPCCH).

• PDSCH (Physical Downlink Shared Channel).carries information to multiple mobiles at the same time.

• AICH (Acquisition Indication Channel).used to indicate to a mobile that the base station has acquired the mobile’s attempt to

contact the network.• PICH (Page Indication Channel).

informs mobiles when pages directed to that mobile will be sent in an future Paging Channel slot.

Pilot Structure

3GPP Uses Two Types of Pilot Channels:

1. Code Based Pilot (CPICH - Common Pilot Channel)• Used To Broadcast Timing Information to All Mobile Stations

Operating in a Cell or Sector• is assigned a unique spreading code. This allows all mobiles in that

cell to decode the pilot channel and use it as a timing reference• The CPICH allows mobile stations to use coherent detection to

increase demodulation performance.

2. Embedded Pilot Signals:• Some Downlink Channels also Included Embedded Pilot Information• Pilot Data is Time Multiplexed into the Channel• Used by Mobiles to Send Timing Information to Base Stations

Common Pilot Channels (CPICH)

Primary CPICH:• Always Uses the 256 bit OVSF Spreading Code 0• Always Uses the Cell’s Primary Scrambling Code• One Per Cell and is Broadcast Over the Entire Cell• send timing information to mobile stations to synchronize with the base station by

using pilot data.

Secondary CPICH:• Same as the Primary CPICH Except - >• Assigned Arbitrary 256 bit OVSF Spreading Code• Can use the Primary or a Secondary Scrambling Code• There can be Any Number of Them• The primary use of the Secondary CPICH will be in the future when beam formed

antennas are implemented.

Downlink P-CCPCH (Primary Common Control Physical Channel)

• Transmits the BCH (Broadcast Channel) Transport Channel.• Sends Cell Information.• Rate Is Fixed to 27 kbps.• Broadcast over the Entire Cell.• The P-CCPCH Does Not Contain Pilot, Power Control, or Rate• Information.• Every Cell Uses only OVSF Code 1 (256 bit).

P-CCPCH Frame Structure

Each Frame is 10 milliseconds in Duration.Each Frame is Divided into 15 Timeslots:• Data Rate is Fixed to 27,000 bps• 18 Data symbols are Sent in each Timeslot• Each timeslot is divided into two sections: an off period where no data is

transmitted, and a data portion that carries the BCH information. • The P-CCPCH Does Not Transmit in the first 66.7 usec. This is done to reduce the

effects of the Sync channel which directly interferes with the other channels in the downlink (more on this in a minute).

P-CCPCH Channel Coding

• the System Frame Number (SFN) is carried by 12 bits of data. The SFN is used by the mobile to align data received from various cells during soft handoff.

• Eight tail bits are also added to reset the initial state of the convolution encoder to all zeroes so as to be ready for the next frame of data.

• At this point, the combined data is passed through a one-half rate convolutional encoder that doubles the data rate to 25.6 kbps.

• Rate matching is performed to bring the final rate up to 27 kbps.

Downlink S-CCPCH (Secondary Common Control Physical Channel)

• Sends the FACH (Forward Access Channel) and the PCH (Paging Channel) Transport Channels.

• The FACH is Pages Mobiles when Their Location is Known.• The PCH is Pages Mobiles when Their Location is Not Known.• The FACH and PCH Can be Combined on one SCCPCH or Sent on Separate SCCPCH Channels.

• Like P-CCPCH , the S-CCPCH Has No Power Control Data, but Optionally Carries Rate Information (TFCI).

• The Rate is Fixed in a Cell but Can Be Different between Cells Depending on Cell Loading 9 (number of pages that need to be sent in a cell).

Downlink Sync ChannelThe Primary SCH is:• An unmodulated, 256 bit Gold Code (Long 10ms code: Gold code)• The Code is Sent at the Beginning of each Timeslot (first 10% of each timeslot (256 bits at 3.84 Mcps = 66.7

usec, eachtimeslot is 667 usec))

• All Base Station use the Same, 256 bit Gold Code, Mobiles search for this pattern when looking for suitable base stations to use.

The Secondary SCH is:• Instead of using a single 256 bit code, the uses a Sequence of 15, 256 bit Gold Codes in each frame.• The Pattern is Sent using the first 256 bits of each Timeslot (15 )• This provides a “hint” to the mobile of which scramble code the base stations is using.• The Pattern of Codes (64 total) correspond to the Scrambling Code (Long Code) Group being used by the

Base Station• The pattern used by the Secondary Sync channel indicates the scramble code group that the base station is

using. In each scramble code group, there are 8 possible scramble codes. Once the mobile reads the Secondary Sync channel and determines the pattern it is using, the mobile then searches for the primary scramble code from the indicated group . The mobile cannot communicate with the base station until it has identified the exact primary scramble code being used.

Both Channels are Orthogonal to Each Other, but are NOT Orthogonal to the Other Channels.

Paging Indicator Channel (PICH)

• This is an optional feature.• Designed to Increase Battery Life for “Sleep Mode”.• Each Phone is Assigned:• A Paging Slot to Check for Paging Messages on the S-CCPCH (Paging Channel)• An Associated Paging Indicator Position on the PICHThe PICH is Aligned to Transmit Ahead of the Associated Paging Slot on the S-

CCPCHMobile Decodes the PICH Channel:• Active Indicator Tells Mobile that a Page is Coming• No Indicator Tells Mobile to Return to Sleep Mode without Reading the Paging

Channel Slot

Downlink DPCH

• The Transport DCH (Dedicated Channel) is Carried on the DPCH (Dedicated Physical Channel)

• The DPCH Consists of the DPDCH (Dedicated Physical DataChannel) and the DPCCH (Dedicated Physical Control Channel).

• The DPDCH and DPCCH are Time Multiplexed together into one Physical Channel.• The DPDCH Carries the User Data for one or more services.• The DPCCH Carries the Control Information for the Physical Layer.

This control information includes embedded pilot data transmit power control bits to control the closed loop transmit power of the

mobile Transport Format Combination Information (TFCI) (optional)

Downlink Convolutional Encoder• Convolutional encoding is used to provide increased error detection and correction

capabilities for the receiver. • The BCH, PCH, and FACH use a one half rate convolutional encoder that double the

bit rate of the input data stream. • The DPCH uses a one third rate or one half rate convolutional encoder for lower

rate services and and a one third rate turbo encoder for higher data rate services.• Uses either a 1/2 or 1/3 Rate Coder• Optionally can use no Encoder

Turbo Coding Option

• To lower the transmit power required for data transmissions (and thus lower the interference and raise capacity), new error correction and detection encoding schemes have been developed.

• These encoders are designed to replace the convolutional encoders and have better correction performance while maintaining the same data rate.

• Unlike Convolutional Codes, Turbo Codes cannot be Described inClosed Mathematical Form:“Trial and Error” Development

• Can Yield up to 0.5 dB Performance Improvement in Required S/N as this reduced the transmit power up to 0.5 dB for the same error rate performance .

Turbo Coder Example

This slide shows the general Turbo Coder specified by 3GPP for high speed data transmissions. Here in this example, data is input to the encoder at arate of 64 kbps. One path in the Turbo Coder simply sends the original data through to the output without modification. This path is known as theSystematic Path. A second path adds redundancy by clocking the data through a feedback shift register system that modifies the data in a predictablemanner. The output of this path is also at a rate 64 kbps. This coded path is called a Parity Path. The third path uses the same coder as the first ParityPath except that the input data is passed through an interleaver. The output of the interleaved Parity Path also runs at 64 kbps. The three resultingdata streams are then multiplexed together to form a single stream that runs at three times the original rate. The net result is that the Turbo Coder has0.5 dB better performance than the convolutional encoder.

Rate MatchingUnequal Repeat or Puncture:• Data is Punctured to a Lower Rate if: 0.8 < Ratio < 1• Otherwise the Data is Repeated up to the Next Rate

In this Example, the DTCH Data is Punctured from 804 bits/frame to 688 bits/frame (40,200 bps to 34,400 bps)

Frame Segmentation & Interleaving

The Logical Channels are:• Individually Interleaved• Converted to 10 ms Frame Structures• Interleaved Together to Form a Dedicated Channel (Transport Channel)

Symbol rate × SF = 3.84McpsWCDMA， SF of uplink channelized code： 4~256

SF of downlink channelized code:4~512OVSF: Orthogonal Variable Spreading Factor

Symbol rate × SF = 3.84McpsWCDMA， SF of uplink channelized code： 4~256

SF of downlink channelized code:4~512OVSF: Orthogonal Variable Spreading Factor

OVSF Code Scramble Code

Data bitChip after Spreading

Spreading of WCDMA

Symbol

Spreading

Despreading

1-1

1-1

1

-1

1-1

1-1

Data = 010010

Spreading code

Spread signal= Data × code

Spreading code =1 -1 -1 1 -1 1 1 -1 ( SF = 8 )

Data = Spread signal × Spread code

Chip

Spreading and Despreading

Orthogonal Variable Spreading Factor Codes -OVSF

• Is used to uniquely identify each channel in the downlink and uplink

• The length of the OVSF code is known as the Spread Factor (SF) since each channel’s data is multiplied by the length of the OVSF code used to spread the channel.

• This Code tree continues down until it reaches SF=512. At the SF=512 point, the set contains 512 unique codes each of which have 512 bits.

• The 3GPP system accommodates channels with different throughput by spreading them with OVSF codes that have a different SF.

• High rate channels must use small SF’s while low rate channels ca nuse longer SFs.

• An OVSF code is first distinguished from other codes in the label Cch (Channelization Code).

Effects of Variable OVSF Codes

• Every code at a given SF is orthogonal to any other code at the same SF.

• codes with a different SF that are not on the same branch are also orthogonal.

• codes that are on the same branch with different SF are NOT orthogonal

• In this picture, a channel uses an OVSF with spread factor equal to four, then all OVSF codes derived from that code ( on the same branch) cannot be used by the base station.

• The more high rate channels are allocated, the number of available OVSF codes for the system to use is greatly reduced.

SF=8

SF=32

SF=16

Characteristic of channelization code

• Premise of code allocation:– ensure not occupied for the code in the root direction and

downwards subtree

• Result of code allocation:– block all low rate SC in subtree and high rate in upwards root

direction

Example

SF=64

SF=32

SF=16

SF= 8

0 1 2 3 4 5 6 7` ` ` `

` `0 1 2 3

` 0 1

0

SF=64

SF=32

SF=16

SF= 8

0 1 2 3 4 5 6 7` ` ` `

` `0 1 2 3

` 0 1

0

0 1 2 3 4 5 6 7` ` ` `

` `0 1 2 3

` 0 1

0

0 1 2 3 4 5 6 7` ` ` `

` `0 1 2 3

` 0 1

0

(a) (b)

(c) (d)

`

Idle

Allocated

Blocked

Orthogonality of OVSF Codes

Like Walsh Codes Used in IS-95 CDMA,OVSF codes are :• Orthogonal with each Other and Their

Inverses:• Orthogonality = Equal Number of

Matches andMismatches Voice Channels Uses the OVSF Code with a SF (spread factor) of 128 The CPICH channel is always spread

with the first 256 bit OVSF code, is denoted by Cch, 256,0

The P-CCPCH is always spread with the second OVSF code with length 256 bits: Cch, 256,1 .

All other channels are assigned OVSF codes by the network.

Downlink Scrambling

OVSF Code Scramble Code

Data bitChip after Spreading

• In addition to spreading, part of the process in the transmitter is the scrambling operation. • This is needed to separate terminals or base stations from each other.• Without the scrambling, each adjacent cell would be using the same OVSF codes, which

would result in high interference.• Scrambling is used on top of spreading, so it does not change the signal bandwidth but only

makes the signals from different sources separable from each other.

Characteristic of Scrambling code• There are 224 Uplink Scrambling Codes, they are used to distinguish

different users in one cell. • Uplink Scrambling codes include long scrambling codes and short

scrambling codes. The Short Scrambling codes are used for multi-user detecting

• There are 218-1 Downlink Scrambling Codes, used to distinguish different cells– Scrambling codes in common use are 0， 1，……， 8191， they are divided

into 512 aggregations， each aggregation has 1primary scrambling code and 15 secondary scrambling codes that are associated with that groups’ Primary code.

– The P-CCPCH always uses the Primary scramble code. Optionally, other channels may be scrambled using the Secondary codes associated with the Primary code.

– 512 primary scrambling codes are further divided into 64 scrambling code groups ,there is 8 primary scrambling in each group. These groups directly correspond to the 64 possible Secondary Sync Channel code patterns.

– When the mobile determines the Secondary Sync Channel code pattern, the mobile then knows which of the 64 Primary scramble codes groups to search to find the exact Primary scramble code of the base station (8 possible codes).

Channelisation code Scrambling code

Usage Uplink: Separation of physical data (DPDCH) and control channels (DPCCH) from same terminal

Downlink: Separation of downlink connections to different users within one cell

Uplink: Separation of mobile

Downlink: Separation of sectors (cells)

Length 4–256 chips (1.0–66.7 s)

Downlink also 512 chips

Different bit rates by changing the length of the code

Uplink: (1) 10 ms = 38400 chips or (2) 66.7 s = 256 chips

Option (2) can be used with advanced base station receivers

Downlink: 10 ms = 38400 chips

Number of codes Number of codes under one scrambling code = spreading factor

Uplink: 16.8 million

Downlink: 512

Code family Orthogonal Variable Spreading Factor Long 10 ms code: Gold code

Short code: Extended S(2) code family

Spreading Yes, increases transmission bandwidth No, does not affect transmission bandwidth

Channelisation and Scrambling Codes

Acquisition Indication Channel ( AICH)

• AICH Provides an Indicator to the Mobile that a PRACH or PCPCHfrom the Mobile has been Detected

• Uses 1.33 ms Access Slots (15 slots per 20ms)• Each Access Slot Provides 16 Access Indicators for 16 Mobiles in

the first 1.067 ms Transmission Period• Each of the 16 AI’s directly corresponds to one of the 16 signature codes

sent by a mobile PRACH or PCPCH .• No Data is Sent Last 4 Symbols of Each Slot• Uses the Same Physical Channel Structure, spreading and modulation as

DPDCH/DPCCH.

Compressed Mode Operation

• Allows “Off” Reception Times for Mobile to Make Measurements on Other Frequencies.

• Two Methods: - Reduce Spread Factor by 2 (Shorter OVSF)

- Puncture Coder (1/3 rate to 1/2 rate)• During the unused timeslots, the mobile can tune its receiver to another

frequency and measure its signal quality.

Physical Uplink Channels

PRACH (Physical Random Access Channel).• Carries the RACH (Random Access Channel)• Used for System Access

PCPCH (Physical Common Packet Channel)• Carries the CPCH (Common Packet Channel)• Used to Carry Small to Medium Packets and Support Contention Resolution

DPCH (Dedicated Physical Channel) Composed of:• DPDCH (Dedicated Physical Data Channel).• DPCCH (Dedicated Physical Control Channel).

Uplink PRACH

• Sends Signaling Information to the Base Station• Is Composed of Two Parts:

• One or More 1.067 ms Duration Preambles which the Base Station Searches for to Acquire PRACH channels

• A 10 ms Message Section• The preambles are repeated until the base station acknowledges receiving

the preamble on the AICH. Once the mobile receives a reception indication on the AICH, it transmits the message portion of the PRACH.

Uplink DPDCH & DPCCH

• DPDCH carries the Data• DPCCH carrier the Layer 1 Control Information(pilot data, TPC, feedback, and

optionally TFCI).• Unlike the Downlink, These Channels are I/Q Multiplexed (BPSK Modulation)• For Higher Data Rate Services, Additional DPDCHs are Added to Both the I and Q

Branches• The DPDCH & DPCCH are Spread with Different OVSF Codes (independent

Channels)– The DPCCH is always spread with the first OVSF code of length 256 (Cch, 256,0). – If only one DPDCH is used, then it is assigned the OVSF code that equals the spread factor divided

by four.In the case of SF=64, as in this example, the DPDCH is spread with OVSF code number 16 (Cch, 64,16)

– If more than one DPDCH is used (multi-code operation for higher rate services), then each are spread with a 4 bit OVSF code (Cch, 4,k).

Call Processing

• Mobile Synchronization• Read Broadcast Channel• Mobile Initial Access:

• Base Station Page, Mobile Response• Mobile Initiated Call

• Move to DPDCH/DPCCH• Soft Handoff

Mobile Initial Search

• The first task for the mobile is to find all receivable primary SCH channels. At this point the mobile station has no timing reference at all

• Since the 3GPP system is completely unsynchronized, the Primary SCH signal from each base station will be received at arbitrary time offsets. Once all of the receivable primary SCHs have been located, the mobile selects the strongest assuming that it probably is the closest base station.

• In this example, the mobile would select Base Station 1 since it provides the strongest signal.

Mobile Synchronization

• Find and Time Sync to Primary SCH Chip Rate• Find and Decode Secondary SCH • Determine Which of the 64 Possible Code Patterns the Secondary SCH is Sending• Begin Search for which of the 8 Possible Scrambling Codes the• Base Station is Using Within the Code Group Defined by the Secondary SCH

Read Broadcast Channel• Once Scrambling Code is Determined, Decode the Broadcast Channel (BCH)• BCH Messages Provide System Specific Information and Cell Parameters

Required for Proper Operation• Cell May Require Registration• Once Complete, Mobile Enters Sleep Mode• Reads PICH to Determine if it Needs to Read PCH• Monitors the PCH or FACH for Page

Mobile Initiated Call

• Sends PRACH Preamble, Waits for AICH Response• Sends PRACH Message• Response on PCH To Get DPDCH/DPCCH Assignment

WCDMA handover types.

• Intra-system handovers: Intra-frequency handovers.• MS handover within one cell between different sectors: softer• MS handover between different BS:

– Soft.– Hard.

Inter-frequency handovers.– Hard

• Inter-system handovers:– Handover between WCDMA <--> GSM900/1800: Hard– Handower between WCDMA/FDD <--> TDD: Hard

Soft Handoff

• A mobile station communicates with two base stations simultaneously• Mobile Searches for Other Cells - looks for Sync Channel• Reports Candidate Cells to System• Receives Assignment for Soft Handoff from Network• Must Determine System Frame Number from Each Cell to Properly

Time Align Each Cell’s Transmissions.– The System Frame Number (SFN) is multiplexed with the BCH transport

channel and is carried over-the-air on the P-CCPCH.

Soft Handover, uplink and downlink

Softer Handover

Handover procedure

• Strength of the A becomes equal todefined lower threshold. Theneighbouring signal has adequatestrength. B is added to active set.• Quality of signal B starts to becomebetter than signal A. The RNC keepsthat point as starting point forhandover margin calculation.• The strength of signal B becomesequal or better than the defined lowerthreshold. Thus its strength isadequate to satisfy the required QoSof the connection. The strength of thesummed signal exceeds thepredefined upper threshold, causingadditional interference to the system.As a result, RNC deletes signal Afrom the Active Set.

Parameter in the handover algorithm• Upper threshold: the level at which the signal strength of the connection is atthe maximum acceptable level in respect with the requested QoS.• Lower threshold: is the level at which the signal strength of the connection isat the minimum acceptable level to satisfied the required QoS. Thus the signalstrength of the connection should not fall below it.• Handover margin: is a predefined parameter, which is set at the point wherethe signal strength of the neighbouring cell (B) has started to exceed the signalstrength of current cell (A) by a certain amount and/or for a certain time.• Active Set: is a set of signal branches (Cells) through which the MS hassimultaneously connection to the UTRAN.• Candidate Set: is a list of cells that are not presently used in the soft handoverconnection, but whose pilot E/I are strong enough to be added to the active set.– Candidate set is not used in WCDMA handover algorithm.• Neighbour Set: The neighbour set or monitored set is the list of cells that themobile station continuously measures, but whose pilot E/I are not stron enoughto be added to the active set.

Active Set Management

HSxPA Motivation and General Principle

• Improved performance and spectral efficiency in DL and UL by introducing a shared channel principle:– Significant enhancement with peak rates up to 14.4 Mbps (28 Mbps in Rel7) in DL, and 2

Mbps (11.5 Mbps with 16QAM) in UL– Huge capacity increase per site; no site pre-planning necessary– Improved end user experience: reduced delay/latency, high response time

HSDPA (3GPP Rel5)

Fast pipe is shared among UEs

Scheduling A,B,C

HSUPA (3GPP Rel6)

Dedicated pipe for every UE in ULPipe (codes and grants) changing with timeE-DCH scheduling

E-DCH - A

E-DCH - B

E-DCH - C

Rel. 99

DCH -A

DCH -B

DCH -C

Dedicated pipe for every UE

HSDPA Overview

15 Code Shared

transmission

16QAMModulation

TTI = 2 ms Hybrid ARQwith incr. redundancy

Fast Link Adaptation

AdvancedScheduling

BenefitHigher Downlink Peak rates: 14 Mbps

Higher Capacity: +100-200%Reduced Latency: ~75 ms

Maximum code allocation for HSDPA

SF=1

SF=2

SF=4

SF=8

SF=16

SF=32

SF=64

SF=128

SF=256

15 HS-PDSCH codes15 HS-PDSCH codes

Up to three HS-SCCH codesUp to three HS-SCCH codesCodes for common channels in the cellCodes for common channels in the cell

Codes for associated DCHs and non-HSDPA users

Codes for associated DCHs and non-HSDPA users

Used by 2 HSDPA UEs no SF256 available for the 3rd UE for associated

DCH

Used by AMR user only one SF128 code remains for associated DCH

Used by HSDPA UE as associated DCH and HS-SCCH

Case1:

Case2:

Case1+2:

– Code tree limitation makes it hard to have 15 codes allocated for HSDPA• Still commonly 14 or 12 or lower amounts are easily available• Note that current terminals support only 10 codes so 15 codes means more than 1 users per TTI

– 15 codes is available but not commonly for cells where has reasonable high traffic (noticing terminal limitation 10 codes, thus fully utilise 15 codes needs minimum 2 HSDPA users)

• Case 1: Allocation of 15 is not possible when more than 2 HSDPA users are active (i.e. 3 HSDPA users)• Case 2: Allocation of 15 is not possible (with two HSDPA users) when 1 AMR12.2 user exists in the cell

HSDPA - UE Categories– QPSK and 16QAM modulation with multicode transmission used to achieve high data

rates– 12 different UE categories defined, categories are characterised by

• Number of parallel codes supported• Minimum inter-TTI interval

– Theoretical peak bit rate up to 14.4 Mbps for category 10 UE using 15 codes and 16QAM

HSUPA Overview

TTI = 10 ms1-4 Code Multi-Codetransmission

FastPower Control

Hybrid ARQwith incr. redundancy

NodeB ControlledSc

heduling

BenefitHigher Uplink Peak rates: 2.0 Mbps

Higher Capacity: +50-100%Reduced Latency: ~50-75 ms

HSUPA - UE Categories– BPSK modulation with multicode transmission used to achieve high data rates– 6 different UE categories defined, categories are characterised by

• Number of parallel codes supported• Support of 2ms TTI - 10ms TTI supported by all the HSUPA UEs

– Theoretical peak bit rate up to 5.74 Mbps for category 6 UE using 2 ms TTI• No coding and no retransmissions - all bits must be delivered correctly over the air…

11484

20000

20000

5772

20000

14484

2798

14484

7110

Transport Block size

2 Mbps102 x SF24

2.89 Mbps22 x SF24

1.45 Mbps102 x SF42

1.40 Mbps22 x SF42

2 Mbps102xSF2 + 2xSF46

6

5

3

1

HSUPACategory

2

10

10

10

TTI

2xSF2 + 2xSF4

2 x SF2

2 x SF4

1 x SF4

Codes x Spreading

5.74 Mbps

2 Mbps

1.45 Mbps

0.71 Mbps

Data rate

HSPA mobility

• HSDPA– Soft handover on associated DCH channels (signalling, UL data)– Serving cell change for HSDPA data channel

• Connected only to one cell at a time

• HSUPA– Soft handover utilised for uplink channels as required due to near-far

problem– Only Serving Cell can allocate more UL capacity/power

HS-SCCH

HS-PDSCH

DPCH

DPCHServing HS-DSCH cell

Notice that soft/softer handoveris not supported for HS-SCCH/HS-PDSCH

UL DCH vs HSDPA vs HSUPA Concepts

HSDPAHSDPA HSUPAHSUPA

ModulationModulation QPSK and 16-QAMQPSK and 16-QAM BPSK and Dual-BPSKBPSK and Dual-BPSK

Soft handoverSoft handover NoNo YesYes

HSUPA is like “reversed HSDPA”, except

Fast power controlFast power control NoNo YesYes

SchedulingScheduling Point tomultipoint

Point tomultipoint Multipoint

to point

Multipoint to point

Non-scheduled transmission

Non-scheduled transmission NoNo Yes, for minimum/

guaranteed bit rate

Yes, for minimum/guaranteed bit rate

Required for near-far avoidance

Efficient UE power amplifier

Scheduling cannot be as fast as in HSDPA

Similar to R99 DCH but with HARQ

HSUPA could be better described as Enhanced DCH in the uplink than “reversed HSDPA”

Feature

Variable spreading factor

Fast power control

Adaptive modulation

BTS based scheduling

DCH

Yes

Yes

No

No

HSUPA

Yes

Yes

No

Yes

Fast L1 HARQ No Yes

HSDPA

No

No

Yes

Yes

Yes

Multicode transmission Yes(No in practice) Yes Yes

HSUPA (E-DCH) is an uplink DCH with BTS-based HARQ and scheduling and true multicode support

Soft handover Yes Yes No(associated DCH only)

Any question???

Thank you