02.Wcdma Channels
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MobileComm Technologies India Pvt. Ltd.
Dallas . Atlanta . Washington . LA . Sao Paulo . New Delhi . Toronto . Muscat. Sydney
WCDMA Channels
Copyright 2010 MobileComm Technologies India Pvt. Ltd. All rights reserved MobileComm is committed to providing our customers with quality instructor ledTelecommunications Training.This documentation is protected by copyright. No part of the contents of thisdocumentation may be reproduced in any form, or by any means, without the prior written consent of MobileComm Technologies .Document Number: RK/CT/3/2010This manual prepared by: MobileComm Technologies MobileComm Technologies(India)Pvt. Ltd.424, First Floor, Udyog Vihar Phase -4, Gurgaon-122002 Headquarter:MobileComm Professionals Inc.1255 West 15th Street, Suite 440Plano, TX, 75075Tel: (972) 633-5100Fax: (972) 633-5106
www.mcpsinc.com
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Section 1 Physical Channel Structure and Function
Section 2 Channel Mapping
Content
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WCDMA Radio InterfaceWCDMA Radio Interface
3GPP protocol defined WCDMA radio interface into three channels: Physical channel, transport channel and logical channel.
Logical channel: Carrying user services. Divided into 2 types, based on services it carried: Control channel and service channel.
Transport channel: Between radio interface layer 2 and
physical layer. Services provided by physical layer for MAC layer. Based on information transported, can be divided into dedicated channel and common channel.
Physical channel: It is the ultimate embodiment of all kinds of information when they are transmitted on radio interfaces. Each channel that uses dedicated carrier frequency, code (spreading code and scramble) and carrier phase can be regarded as a dedicated channel.
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Logical channelLogical channel
Traffic channel
Control channel
Dedicated traffic channel ( DTCH)Common traffic channel ( CTCH)
Broadcast control channel ( BCCH)Paging control channel ( PCCH)Dedicate control channel ( DCCH)Common control channel (CCCH)
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Transport channelTransport channel
Broadcast channel (BCH)Forward access channel (FACH)Paging channel (PCH)Random access channel (RACH)
BCH, FACH & PCH are downlink channels.
Only RACH is common uplink channel
Dedicated Channel (DCH)Dedicated Channel (DCH) exists on uplink or downlink channel.
Dedicated transport channel
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Physical ChannelPhysical Channel
A physical channel is defined by a specific carrier frequency, code (scrambling code, spreading code) and relative phase.
In UMTS system, the different code (scrambling code or spreading code) can distinguish the channels.
Most channels consist of radio frames and time slots, and each radio frame consists of 15 time slots.
Two types of physical channel: UL and DL
Physical Channel
Frequency,code,phase
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Downlink Physical ChannelDownlink Physical Channel
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
Downlink Physical Channel
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Functions of Downlink DPDCH/DPCCH Functions of Downlink DPDCH/DPCCH
DCH data
DPDCH
DPCCH
Provide control data for DPDCH ,such as demodulation, power control,etc.
Data bearer at physical layer
DCH data
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Common Pilot Channel(CPICH)Common Pilot Channel(CPICH)
Common Pilot Channel (CPICH) Carries pre-defined sequence. Fixed rate 30Kbps , SF=256 Can use STTD on this channel
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Common Pilot Channel (CPICH) Common Pilot Channel (CPICH)
Primary CPICH Uses OVSF code -Cch, 256,0 Scrambled by the primary scrambling code Only one CPICH per cell Broadcast over the entire cell The P-CPICH is a phase reference for SCH, Primary CCPCH,
AICH, PICH. By default, it is also a phase reference for downlink DPCH.
Secondary CPICH An arbitrary channel code of SF=256 is used for S-CPICH S-CPICH is scrambled by either the primary or a secondary
scrambling code There may be zero, one , or several secondary CPICH. S-CPICH may be transmitted over part of the cell S-CPICH may be a phase reference for S-CCPCH and downlink
DPCH.
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Synchronization Channel (SCH)Synchronization Channel (SCH)
Used for cell search Two sub channels: P-SCH
and S-SCH. SCH is transmitted at the
first 256 chips of every time slot.
PSC is transmitted repeatedly in each time slot.
SSC specifies the scrambling code groups of the cell.
SSC is chosen from a set of 16 different codes of length 256, there are altogether 64 primary scrambling code groups.
Primary SCH
Secondary SCH
256 chips
2560 chips
One 10 ms SCH radio frame
acsi,0
acp
acsi,1
acp
acsi,14
acp
Slot #0 Slot #1 Slot #14
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Primary Common Control Physical Channel (PCCPCH)Primary Common Control Physical Channel (PCCPCH)
Fixed rate( 30kbps, SF=256, 1) Carry BCH transport channel Not transmitted during the first 256 chips of each time slot. Only data part STTD transmit diversity may be used
Data 18 bits
Slot #0 Slot #1 Slot #i Slot #14
Tslot = 2560 chips , 20 bits
1 radio frame: Tf = 10 ms
(Tx OFF)
256 chips
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Secondary Common Control Physical Channel (SCCPCH)Secondary Common Control Physical Channel (SCCPCH)
Carry FACH and PCH. Two types of SCCPCH: with or without TFCI.
UTRAN decides if a TFCI should be transmitted, UE must support TFCI.
Possible rates are the same as that of downlink DPCH
SF =256 - 4. FACH and PCH can be
mapped to the same or separate SCCPCHs. If mapped to the same S-CCPCH, they can be mapped to the same frame.
Slot #0 Slot #1 Slot #i Slot #14
Tslot = 2560 chips, 20*2k bits (k=0..6)
Pilot Npilot bits
Data Ndata bits
1 radio frame: Tf = 10 ms
TFCI NTFCI bits
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Paging Indicator Channel (PICH) Paging Indicator Channel (PICH)
One radio frame (10 ms)
b1 b0
288 bits for paging indication 12 bits (undefined)
b287 b288 b299
Fixed-rate (SF=256, 3), used to carry the Paging Indicators (PI). PICH is always associated with an S-CCPCH to which a PCH
transport channel is mapped to. N paging indicators {PI0, …, PIN-1} in each PICH frame, N=18,
36, 72, or 144. If a paging indicator in a certain frame is set to 1, it indicates
that UEs associated with this paging indicator should read the corresponding frame of the associated S-CCPCH.
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Acquisition Indicator Channel (AICH)Acquisition Indicator Channel (AICH)
Frame structure of AICH: two frames, 20 ms , consists of a repeated sequence of 15 consecutive AS, each of length 20 symbols(5120 chips). Each time slot consists of two parts, an Acquisition-Indicator(AI) and a part of duration 1024chips with no transmission.
Acquisition-Indicator AI have 16 kinds of Signature. CPICH is the phase reference of AICH.
AS #14 AS #0 AS #1 AS #i AS #14 AS #0
a1 a2a0 a31 a32a30 a33 a38 a39
AI part Unused part
20 ms
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Uplink Physical Channel Uplink Physical Channel
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
Physical Channel
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Physical Random Access Channel (PRACH) Physical Random Access Channel (PRACH)
The PRACH consist of 2 parts: Preamble
one or several preamble. Each preamble is of length 4096chips and consists of 256
repetitions of a signature whose length is 16 chips. Total of 16 signatures
SF : 256 Message part :
Two type, 10 or 20ms message part SF : 256 - 32
Which signature is available and the length of message part are determined by higher layer
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PRACH Transmission StructurePRACH Transmission Structure
Message part Preamble
4096 chips 10 ms (one radio frame)
Preamble Preamble
Message part Preamble
4096 chips 20 ms (two radio frames)
Preamble Preamble
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Function of physical channel
P-CCPCH-Primary common control physical channel
SCH- Synchronisation Channel
P-CPICH-Primary common pilot channel S-CPICH-secondary common pilot channel
Cell broadcast channels
DPDCH-dedicated physical data channel
DPCCH-dedicated physical control channel
Dedicated channels
Paging channels
PICH-paging Indicator Channel
S-CCPCH-Secondary common control physical channel
PRACH-Physical random access channel
AICH-Acquisition Indicator Channel
Random access channels
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Channel Mapping
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Cell search procedure
(P-SCH) Primary SCH
(S-SCH) Secondary SCH
CPICH
P-CCPCH P-CCPCH
Slot synchronisation to
a cell
10 ms
The Primary CCPCH is detected using the identified primary scrambling code After the cell search, system and cell specific BCH information can be read.
Frame synchronisation and identification of the cell code
group
Determination of the exact primary scrambling code
used by the found cell
Phase 1
Phase 2
Phase 3
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Cell search procedure
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15
15
scramblingcode group
group 00
group 01
group 02
group 03
group 05
group 04
group 62
group 63
1 1 2 8 9 10 15 8 10 16 2 7 15 7 16
1 1 5 16 7 3 14 16 3 10 5 12 14 12 10
1 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 7
1 2 16 6 6 11 5 12 1 15 12 16 11 2
1 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 11 11 13 12 16 10
slot number0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
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11 11
11 11
11 11
11 11
15
15
15
15 15
15
15
15 15
15 15
5
5
SSC Allocation for S-SCH
I monitor the S-SCH
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Call procedures
Power OFF
PLMN selection
IDLE mode
CONNECTED mode
Cell search
Cell selection
System information (BCH)
Power ON
Location registration
Cell reselection
RACH procedure
RACH procedure
RRC Connection
Paging
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Paging procedure (2/2)
• A cell can have configured more than one S-CCPCH + PICH for paging. The configuration type is specified in SIB 1 and SIB 5.
UE reads System info (SIB 5)
UE evaluates which S-CCPCH
UE evaluates how often to check PI from PICH
UE evaluates when to check PI from
PICHUE evaluates which PI
to check
Paging procedure
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Random access procedure
UE
RRC: System Information (BCCH / BCH /
PCCPCH)
1. PRACH Preamble (P1)
2. PRACH Preamble (P2=P1
+P0)
3. AICH: Acquisition Indication
4. RRC : RRC Connection Request
(RACH / PRACH Message (P3=P2
+Pm-p)) WBTS
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Random access procedure
UE
•Location Update•Authentication•Security Mode Setup•Paging•Call Setup
1. Location Update
Request
2. Authentication and Security Mode
Setup
3. Location Update Accept
4. Paging
5. Call Setup
MSC / VLR
WBTS
Ciphering and Integrity Protection
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DEDICATED CHANNEL PROCEDURE
Figure :Dedicated channel establishment-mobile terminated call
UE in Idle Mode
1. PI on the PICH
2. PCH message on the S-CCPCH
3. UE ramps up the power by sending preambles
4. Node B responds on the AICH
5. UE sends the RACH message
6. FACH message on S-CCPCH
7. DL-DPCH ramp up
8. UE sends UL-DPCH
DPCH established
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MOC Call Setup