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What do YOU hear...

If you only speak Japanese?

If you only speak English?

If you only speak Italian?

If you only speak Japanese, but the Japanese-speakingperson is all the way across the room?

If you only speak Russian, but the Spanish-speakingperson is talking very loudly?

WCDMA Cocktail Party

2


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Duplex Spacing: 190 MHz

FDD

Time

Frequency

Power

5 MHz 5 MHz

Code

Multiplex

UL DL

UMTS USER 1

UMTS USER 2

Time

Frequency

Power

TDD

5 MHz

Code Multiplex

&

Time Division

666.67 s

DL

UL

DL

DL

UL

UMTS USER 2

UMTS USER 1

W-CDMA: FDD or TDD

3

UMTS Air Interface technologies


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W-CDMA FDD mode for the paired band

uplink and downlink are separated in frequency

TD-CDMA TDD modefor the unpaired band

uplink and downlink are separated in time flexible time duration for uplink and downlink for asymmetrical traffic

4

UMTS Air Interface technologies


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UMTS & GSM Network Planning

GSM900/1800: 3G (WCDMA):

Diff b WCDMA & GSM


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Differences between WCDMA & GSM

7

WCDMA GSM

Carrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 118

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

WCDMA F


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WCDMA Features

Separate users through different codes

Large bandwidth

Code planning - Frequency reuse is 1

No frequency planning

Scrambling code planning

5 MHz carrier separation

Fast Power Control

Soft/Softer Handover

Admission Control

Load Control

8

frequency

Code-DivisionMult ip le Access

code

CDMA


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Separates users through different codes

Codes are used for two purposes:

Differentiate channels/users

Spreading the data over the entire bandwidth

f

Code

t

MS 1

MS 2

MS 3

5 MHz

Spreading Principle

9

Direct Sequence Spreading - Code Division Multiple Access (DS-CDMA)


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WCDMA Codes

Scrambling codes Separates different mobiles (in uplink)

Separates different cells (in downlink)

Channelization codes Separates different channels that are transmitted on the same

scrambling code

Orthogonal Variable Spreading Factor (OVSF) codes

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CDMA i i l Chi & Bi & S b l


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Spreading Code

Spread Signal

Data

Air Interface

Bits (In this drawing, 1 bit = 8 Chips SF=8)

Baseband Data

-1

+1

+1

+1

+1

+1

-1

-1

-1

-1

ChipChip

CDMA principle - Chips & Bits & Symbols

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Spreading Technology


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Spreading Technology

Spreading consists of 2 steps Channelization operation: Transforms data symbols into chips. Thus

increasing the bandwidth of the signal. The number of chips per datasymbol is called the Spreading FactorSF.The operation is donethrough multiplication with OVSF code.

Scrambling operation is applied to the spreading signal.

Data bit

OVSFcode Scramblingcode

Chips afterspreading

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DL & UL Ch li i C d


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DL & UL Channelisation Codes

Walsh-Hadamard codes: orthogonal variable spreading factor codes (OVSF

codes) SF for the DL transmission in FDD mode = {4, 8, 16, 32, 64, 128, 256, 512}

SF for the UL transmission in FDD mode = {4, 8, 16, 32, 64, 128, 256}

Orthogonal codes are suited for channel separation.

Downlink channels under one cell

Uplink channels from a single user

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Channelization Codes


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Channelization Codes

14

CC1, CC2CC3, CC4

CC5, CC6, CC7

CC1 , CC2, CC3CC1, CC2

CC1, CC2, CC3, CC4

In the Uplink, Channelization Codes are used to distinguish between data (andcontrol) channels from the same UE

In the Downlink, Channelization Codes are used to distinguish between data

(and control) channels coming from the same NodeB

Channelization Codes have different length depending on the bit rate

Scrambling Codes


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After the Channelization Codes, the data stream is multiplied by a special code todistinguish between different transmitters.

Scrambling codes are not orthogonal so they do not need to be synchronized

The separation of scrambling codes is proportional to the code length longercodes, better separation (but not 100%)

Scrambling codes are 38400 chips long

Scrambling Codes

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DL & UL Scrambling Codes


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DL & UL Scrambling Codes

DL Scrambling Codes

Pseudo noise codes used for cell separation

512 Primary scrambling codes

Always long scrambling codes used

UL Scrambling Codes

Two different types of UL scrambling codes are generated

Long scrambling codes of length of 38 400 chips = 10 ms radio frame

Short scrambling codes of length of 256 chips

Long code used if base station uses rake receiver, otherwise short codesused

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512 DL Primary Scrambling Codes16.8 million UL Scrambling Codes

Scrambling Codes


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Scrambling Codes

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SC3 SC4

SC5 SC6

SC1 SC1

Cell 1 transmits using SC1

SC2 SC2

Cell 2 transmits using SC2

In the Downlink, the Scrambling Codes are used to distinguish each cell(assigned by operator SC planning)

In the Uplink, the Scrambling Codes are used to distinguish each UE (assignedby network)

Transmission Power


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Transmission Power

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Frequency

5MHz

Power density

Time

High bit rate user

Low bit rate user

Correlation between: Capacity, Interference, Load & Power

Channelisation and Scrambling Codes


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Channelisation code Scrambling code

Usage Uplink: Separation of physical dataand control channels from same

terminal

Downlink: Separation of downlinkconnections to different users withinone cell

Uplink: Separation of mobile

Downlink: Separation of sectors(cells)

Length 2256 chips (0.566.7 ms)

Different bit rates supported bychanging the length of the code

10 ms = 38400 chips

Number ofcodes

Number of codes under onescrambling code = spreading factor

Uplink: 16.8 million

Downlink: 512

Code family Orthogonal Variable SpreadingFactor, walsh codes

10 ms code: Gold code

Spreading Yes, increases transmissionbandwidth

No, does not affect transmissionbandwidth

g

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Codes Multiplexing


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Scrambling code

Channelization code 1



User 1 signal

User 2 signal

User 3 signal

Node B

p g

1 - Downlink Transmission on a Cell Level

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Codes Multiplexing


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NodeB

Channelization code

2 - Uplink Transmission on a Cell Level

21

Scrambling code 2

User 2 signal

Scrambling code 3

User 3 signal

Channelization code

Channelization code

Scrambling code 1

User 1 signal

p g


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WCDMA Channels

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WCDMA Channels


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Logical Channels are not actually the channel rather they can defined as a different

task performed by the network and the UE at different times.They describes the type of information to be transferred..

It comes into two groups:

Control Channels

Traffic Channels

Controls channels carry the control plane information

Traffic Channels carry the user plane information

Transport channels describes how the logical channels to be transferred. Or it can

be defined by how and with what characteristics data is transferred over the

interface.


Dedicated Channels

Common Channels

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Physical Channel

A physical channel is defined by a specific carrier frequency, code (scramblingcode, spreading code) and relative phase.

In UMTS system, the different code (scrambling code or spreading code) candistinguish the channels.

Most channels consist of radio frames and time slots, and each radio frameconsists of 15 time slots.

Two types of physical channel: UL and DL

Physical Channel

Frequency,code,phase

Radio Interface Channel Organization


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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

g

Radio Frame Structure


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26

In WCDMA the information is spread over 5MHz band (Wide Bandwidth). There

are separate radio channels for both uplink and downlink of 5MHz.One radio frame consist of 38400 chips and 15 slots. The duration of the radio

frame is 10ms which have ship rate of 3.84 Mcps. Each slots in the radio frame

comprises of 2650 chips.

frame #i frame #i+1

timeslot #0 timeslot #1 timeslot #2 timeslot #13 timeslot #14

Radio Frame (10ms)

Time Slot (2560*Tc)

Logical Channels


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Broadcast Control Channel (BCCH):

It broadcast system control information for all mobiles in a cell like Code values in

the cell, neighbors information, allowed power levels in downlink direction.

Paging Control Channel (PCCH):

It transfer paging information in downlink direction. Network page the mobile to

discover the UE location or UE in a cell connected state.

Common Control Channel (CCCH):

Network may have certain tasks which are or may be common to UE in the cell. Itsbeing used in both direction downlink & uplink. The CCCH is also used when UE is

accessing a new cell after cell reselection.

Dedicated Control Channel (DCCH)

When there is dedicated/active connection means RRC connection between the

network and the mobile, the control information transferred using DCCH. Its an bi-directional channel.

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Logical Channels


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Dedicated Traffic Channel (DTCH):

It is used transfer the user data between the network and the

mobile in both uplink and downlink direction.

Common Traffic Channel (CTCH):

It is used the transfer the data from one point to all mobile or a

specified group of mobiles.

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Transport Channels


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Transport channels describes how the logical channels to be transferred

Transport channel is defined by how and with what characteristics data is transferred overthe interface.


Dedicated Channels

Common Channels

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Transport Channels


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Common Transport Channels:

Forward Access Channel (FACH):

It is a downlinkcommon channel used to send small amounts of control and user data.

Broadcast Channel (BCH):

It broadcast system information in the downlinkdirection for all mobile stations in a cell.

Paging Channel (PCH):

Its a downlinkcommon channel used to send paging notification messages.Random Access Channel (RACH):

It is used to send a control information from UE in the uplinkdirection. Also may carry short users

packet.

Dedicated Transport Channels:

Dedicated Channel(DCH)

It is a channel that is used to send dedicated control and user data between the UE and the network in

both uplink & downlink direction.

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Physical Channel


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In uplink and downlink direction, each slot in a radio frame defined with a

code or a set of codes that carries a set of common and dedicated channelscalled Physical Channel.

The information rate of the channel varies from 15 kbps to 1920 kbps for

downlink and 30 kbps to 1920 kbps corresponding to available Spreading

Factor. In Uplink spreading factor from 256 to 4 and in downlink from 512 to

4.

Physical channels are the transmission media providing platform (radio)

through which information is going to be transferred

Physical Channels means different kinds of bandwidths allocated for

different purposes, its actually is the physical existence of the Uu interface

between UE domain and Access domain.

Physical channel are defined by specific carrier freq, scrambling andchannelization code

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Downlink Physical Channel


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Downlink Common Physical Channel

Common Pilot Channel (CPICH)

Synchronization Channel (SCH)

Common Control Physical Channel (CCPCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Downlink Dedicated Physical Channel Downlink DPCH

Downlin

PhysicaChanne

Uplink Physical Channel


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Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel

(Uplink DPDCH)

Uplink Dedicated Physical Control Channel

(Uplink DPCCH)

Uplink

Physica

Channe

Physical Channels- Uplink


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Dedicated Physical Control Channel(DPCCH)

For each radio link, there is one DPCCH, it carries control information like

Pilot bits (used to support channel estimation at rake receiver) Transmit Power Control (TPC) commands (Used power control)

Feedback information (FBI) needed with transmit diversity

Transport Format Combination Indicator (TFCI)

Spreading factor is always 256.

Dedicated Physical Data Channel(DPDCH)

Each radio link may have no DPDCHs or several DPDCHs.

Spreading factor for the DPDCH can be between 256 and 4.

DPCCH & DPDCH are time multiplexed in downlink but in uplink these are I/Q

modulation.

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PilotNpilotbits

TPCNTPCbits

DataNdatabits

Slot #0 Slot #1 Slot #i Slot #14

Tslot= 2560 chips, 10 bits

1 radio frame: Tf= 10 ms

DPDCH

DPCCHFBI

NFBIbitsTFCI

NTFCIbits

Tslot= 2560 chips, Ndata= 10*2kbits (k=0..6)

Slot #2 Slot #3

Subframe #0 Subframe #1 Subframe #2 Subframe #3 Subframe #4

1 subframe = 2 ms

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Physical Random Access Channel (PRACH)

It carries the Random Access Channel (RACH transport Channel). UE useswhen physical random access procedure is initiated.

36

Message partPreamble

4096 chips

10 ms one radio frame

Preamble Preamble

Message partPreamble

4096 chips 20 ms (two radio frames)

Preamble Preamble



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RACH Preamble Part

Each preamble is of length 4096 chips and consist of 256 repetitions of a signature of

length 16 chips.

RACH Message PartThe 10 ms message part spilt into 15 slots each length of 2560 chips. Each slot consis

of data part onto which RACH transport part is mapped and control part tha

carries layer 1 control information. The 20ms message consists of two consecutive

10ms message part radio frames.

37

Pilot

Npilotbits

Data

Ndatabits


Tslot= 2560 chips, 10*2kbits (k=0..3)

Message part radio frame TRACH= 10 ms

Data

ControlTFCI

NTFCIbits

Physical Channels- Downlink


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Downlink Dedicated Channel:

In downlink there is only one dedicated channel DPCH. The controldata and user data are time multiplexed with one DPCH.

The length of frame is 10 ms divided into 15 slots

The no. of bits in the data part depends on the spreading factorbetween 512 and 4 correspondence of 15kbps to 1,920kbps.

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DPCCH + DPDCH

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Primary Common Pilot channel (P-CPICH)

It has following characteristics:

The same channelization code is always used

The P-CPICH is scrambled by primary scrambling code

There is only one P-CPICH per cell

The P-CPICH broadcast over the entire cell

Secondary Common Pilot Channel (S-CPICH)

It has following characteristics:

An arbitrary channelization code is used SF256

A S-CPICH may scrambled with primary or secondaryscrambling code

There may be zero, one or several S-CPICH per cell

A S-CPICH transmitted over the entire cell or part of the cell41



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Primary Common Control Physical Channel (P-CCPCH) (Cell n N/w Info)

It has fixed bit rate of 30 Kbps (Fixed Scrambling code 256)

There are no TPC, Pilot bits and first 256 chips of the slot are used for the primaryand secondary synchronization Channel. This used to carry the FACH and thePCH.

42

DataNdata1=18 bits


Tslot= 2560 chips , 20 bits


(Tx OFF)

256 chips


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P-CCPCH + SCH

43



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Secondary Common Control Physical Channel (S-CCPCH)

It has variable bit rate from 30kbps to 1,920 kbps. There are data bits, pilot bits andoptional TFCI bits. It is transmitted only to smaller are of the cell.

44


Tslot= 2560 chips, 20*2kbits (k=0..6)

Pilot

Npilotbits

Data

Ndata1bits


TFCI

NTFCIbits


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Synchronization ChannelThis channel used in the cell search procedure. It is divided into the Primary Synchronization

and Secondary Synchronization Channel

Primary Synchronization Channel

It carries primary synchronization codes transmitted in each slot of a radio frame. It is samefor cells in the network.

Secondary Synchronization Channel

It consist of the secondary Synchronization codes (SSC). System selects the SSC to be

transmitted in a slot, based on the scrambling code group and the slot number.

46

PrimarySCH

SecondarySCH

256 chips

2560 chips

One 10 ms SCH radio frame

acs,

acp

acs,

acp

acs,

acp

Slot #0 Slot #1 Slot #14



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Acquisition Indicator Channel (AICH)

It is used in a random access procedure by the network to indicate that the RACH preamblewas detected.

It has 15 consecutive access slots.

Length of access slot is 5120 chips

Each access slot is further divided into 32 Acquisition indicators and one part has no

transmission.

47

1024 chips

Transmission Off

AS #14 AS #0 AS #1 AS #i AS #14 AS #0

a1

a2

a0

a31

a30

AI part =

4096 chips, 32 real-valued signals

20 ms

WCDMA Physical Channels


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48

Node B

UserEquipment

(UE)

P-CCPCH- Primary Common Control Physical Channel

SCH - Synchronization Channel

CPICH - Common Pilot Channel

Channels broadcast to all UE in the cell

DPDCH - Dedicated Physical Data Channel

DPCCH - Dedicated Physical Control Channel

Dedicated Connection Channels

PICH - Page Indicator Channel

Paging Channels

S-CCPCH - Secondary Common Control Physical Channel

PRACH - Physical Random Access Channel

AICH - Acquisition Indicator Channel

Random Access and Packet Access Channels


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Thank you

02.wcdma fundamantels and channels

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