Tài liệu WCDMA Channels pptx

In uplink and downlink direction, each slot in a radio frame is defined with a code or a set of codes that carries a set of common and dedicated channels called Physical Channel.. Dedica

WCDMA Channels

10th Aug 2007

Deepak

Logical Channels are not actually channels but rather they can

be defined as different tasks performed by the network and the

UE at different times

• They describe the type of information to be transferred

•Logical channels are categorized into control channels and traffic channels

•Control channels carry the control plane information

•Traffic Channels carry the user plane information

Transport channels describes how the logical channels will be transferred, or it can be defined as how and with what

characteristics data is transferred over the interface

It comes into two groups:

Dedicated Channels

Common Channels

WCDMA Channels

Radio Frame Structure

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)

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

defined with a code or a set of codes that carries a set of common

and dedicated channels called 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 Downlink 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 and channelization code

Physical Channel

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 Its being 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 a bi-directional channel

Logical Channel

Dedicated Traffic Channel (DTCH):

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

UE in both uplink and downlink directions

Common Traffic Channel (CTCH):

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

a specified group of mobiles

Transport Channels

 Transport channels describes how the logical channels to be

transferred

 Transport channel is defined by how and with what characteristics

data is transferred over the interface.

 It comes into two groups:

 Dedicated Channels

 Common Channels

Transport Channels

 Dedicated Traffic Channels:

Dedicated Channel (DCH):

It is the channel used to send dedicated control and user data between UE and the

network in both uplink & downlink directions

Enhanced Dedicated Channel (E-DCH):

It is a enhanced uplink transport channel

 Common Transport Channel :

Random Access Channel (RACH):

It is used to send a control information from UE in the uplink direction Also may carry

short user packets

Common Packet Channel (CPCH):

Its an uplink shared channel used for packet data Several UE can use the same

channel for data transfer

Transport Channels

Forward Access Channel (FACH):

It is a downlink common channel used to send small amounts of control and

user data.

Downlink Shared Channel (DSCH):

It is common channel used to send dedicated control and user data.

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

UE and the network in both directions.

Physical Channels

channels.

Dedicated Channels:

Dedicated Physical Data Channel (DPDCH)

Dedicated Physical Control Channel (DPCCH)

Common Channels:

Physical Random Access Channel

Physical Common Packet Channel

Physical Channels

Dedicated Physical Control Channel

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

information like

control)

Spreading factor is always 256.

Tslot = 2560 chips, 10 bits

Physical Channels

Dedicated Physical Data Channel

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

uplink these are I/Q modulation.

Physical Channels

It carries the Random Access Channel (RACH transport Channel)

UE uses when physical random access procedure is initiated.

Message part Preamble

4096 chips

10 ms (one radio frame) Preamble Preamble

Message part Preamble

Preamble Preamble

Physical Channels

RACH Preamble Part

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

signature of length 16 chips.

RACH Message Part

The 10 ms message part spilt into 15 slots each length of 2560 ships Each slot

consist of data part onto which RACH transport part is mapped and control part that carries layer 1 control information The 20ms message consists of two consecutive 10ms message part radio frames.

Pilot

N pilot bits

Data

N data bits

T slot = 2560 chips, 10*2k bits (k=0 3)

Message part radio frame T RACH = 10 ms

Data

TFCI bits

Physical Channels

 Physical Common Packet Channel (PCPCH)

It carries Common Packet Channel (CPCH Transport Channel) The

access transmission consists of Access Preambles (AP), one

collision Detection Preamble (CDP), a DPCCH Power Control Preamble (PCP) and message Check out the Structure from ECE book.

Physical Channels

Downlink Dedicated Channel

control data and user data are time multiplexed with one DPCH.

between 512 and 4 correspondence of 15kbps to 1,920kbps.

One radio frame, Tf = 10 ms

TPC

NTPC bits

Tslot = 2560 chips, 10*2k bits (k=0 7)

Data2

Ndata2 bits

DPDCH TFCI

DPCCH + DPDCH

Physical Channels

Common Pilot Channel

It has pre-defined bit sequence transmitted with a bit rate of 30 Kbps (Fixed

Scrambling code 256)

CPICH is divided into pilot channels:

Primary Common Pilot Channel (P-CPICH)

Secondary Common Pilot Channel (S-CPICH)

Reason for low bit rate as it is transmitted with high power to reduce the

interference It is phase reference, must be transmitted in whole cell.

Pre-defined bit sequence

T slot = 2560 chips , 20 bits

1 radio frame: T f = 10 ms

Physical Channels

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 secondary scrambling code

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

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

Physical Channels

Primary Common Control Physical Channel (P-CCPCH)

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

primary and secondary synchronization Channel This used to carry the FACH and the PCH

Data

Ndata1=18 bits

Tslot = 2560 chips , 20 bits

1 radio frame: Tf = 10 ms (Tx OFF)

256 chips

P-CCPCH + SCH

Physical Channels

Secondary Common Control Physical Channel (S-CCPCH)

It has variable bit rate from 30kbps to 1,920 kbps There are data bits, pilot

bits and optional TFCI bits It is transmitted only to smaller are of the cell.

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

NTFCI bits

The only difference between the P-CCPCH and S-CCPCH the transport channel mapped on this can only have fixed

predefined transport format combination and in case S-CCPCH support multiple transport format combination using TFCI

Physical Channels

Physical Channels

Synchronization Channel

This 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

same for 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

Physical Channels

Physical Downlink Shared Channel (PDSCH)

It is used for data transmission by one or-several simultaneous users in the

The CPCH Status Indicator Channel (CSICH) is associated with a CPCH This

is uses the free spaces that occurs in the AICH It is used to inform the

UE about CPCH existence and configuration The duration of CSICH is 20ms Each frame consist of 15 slots The length of slot is 40 bits Each slot has a part that is no transmitted and a status indicator part that includes 8 status indicator bits.

Physical Channels

Acquisition Indicator Channel (AICH)

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

preamble was 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

1024 chips Transmission Off

Channel Mapping

•The data can be sent through logical layer via

different channels in the transport layer

•And also one transport channel can be sent via different physical channels

•These selection of channels in the transport and physical layer depends on the data itself and radio resource management and its parameters.

Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) Fractional Dedicated Physical Channel (F-DPCH) E-DCH Dedicated Physical Data Channel (E-DPDCH) E-DCH Dedicated Physical Control Channel (E-

DPCCH) E-DCH Absolute Grant Channel (E-AGCH) E-DCH Relative Grant Channel (E-RGCH) E-DCH Hybrid ARQ Indicator Channel (E-HICH) Physical Random Access Channel (PRACH)

Common Pilot Channel (CPICH) Primary Common Control Physical Channel (P- CCPCH)

Secondary Common Control Physical Channel CCPCH)

(S-Synchronisation Channel (SCH) Acquisition Indicator Channel (AICH) Paging Indicator Channel (PICH)

MBMS Notification Indicator Channel (MICH) High Speed Physical Downlink Shared Channel (HS- PDSCH)

HS-DSCH-related Shared Control Channel SCCH)

(Dedicated Physical Control Channel (uplink) for

Burst Types – Dedicated Physical Channel

 There are four different types of bursts

 All contains two data fields, midamble and GP.

 Length of each is different in each bursts.

 The no of data symbol depends on SF or burst type.

Burst Type - I

 This burst type used for both Uplink and Downlink

 It has larger training sequence due to longer midamble field

 Data field has 976 chips long, no of symbol depends on the SF

 Midamble is 512 chips long and GP is 96 chips period.

Chip number (CN) Length of field in chips Length of field in symbols Contents of field

2560*Tc

Burst Type - II

 This burst type used for both Uplink and Downlink

 It has shorter training sequence due to longer midamble field

 Data field has 1104 chips long, no of symbol depends on the SF

 Midamble is 256 chips long and GP is 96 chips period.

Chip number (CN) Length of field in chips Length of field in symbols Contents of field

2560*Tc

Data symbols

1104 chips

Burst Type - III

 This burst type used for Uplink only

 It has longer guard period suitable for initial access or accss to new cell after

handover

 Data field has 976 and 880 chips long, no of symbol depends on the SF

 Midamble is 512 chips long and GP is 192 chips period.

Data symbols

976 chips Midamble512 chips

GP 192 CP

2560*Tc

Data symbols

880 chips

Chip number (CN) Length of field in chips Length of field in symbols Contents of field

Burst Type - IV

 This burst type used for downlink MBSFN

 It has longer guard period suitable for initial access or accss to new cell after

handover

 It has two data fiels each of 1056 chips long, no of symbol depends on the SF

 Midamble is 320 chips long and GP is 128 chips period.

Data symbols

1056 chips

Midamble 320 chips

Data symbols

1056 chips

GP 128 CP

2560*Tc

Chip number (CN) Length of field in chips Length of field in symbols Contents of field

 Transmission of TPC burst is done in the data parts of traffic burst.

 Data in TPC is always transmit at SF 32 irrespective SF of user data

 TPC information is to be transmitted immediately after the midamble

 Shall be transmitted with same channelization code and timeslot of TFCI

TPC field

512/256 chips 2560*T c

 In Uplink, independent to the SF of data bits TFCI code is applied with SF 32

 TFCI is code to be transmitted directly adjacent to the midamble

512/320/256 chips

2560*Tc

1 st part of TFCI code word 2 nd part of TFCI code word

Questions and discussion