5/038 13 - en/lzu 108 5306 rev a wcdma air interface part 5: 1 of 34 wcdma air interface training...
TRANSCRIPT
Part 5: 1 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Air Interface Training
Part 5 WCDMA Acquisition,
Synchronization,and Handover
Part 5: 2 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Physical Layer Procedures
• Physical Layer Timing and procedures
BS Downlink timing
Fast Synchronization Codes
Synchronization Code 1 (PSC)
Synchronization Code 2 (SSCi)
Downlink Scrambling Codes
Used by UE to distinguish desired Base Station
8192 possible codes, 64 Scrambling Code Groups
Slot Synchronization
Frame Synchronization
System Timing Synchronization
Soft Handover
Random Access protocol
Packet Access protocol
Inter-Frequency Handover
Part 5: 3 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Downlink Transmission Timing
Secondary SCH
Primary SCH
S-CCPCH,k
10 ms Frame
P-CCPCH, (SFN modulo 2 = 0) P-CCPCH, (SFN modulo 2 = 1)
CPICH (Common Pilot Channel)
AICH access slots #0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4
Any PDSCH
PICH
DPCH,n
Common PilotChannel
Primary CCPCH(Broadcast Data)
Secondary CCPCH(Paging, Signaling)
Paging Indication Channel
SCH (PSC+SSC)P-CCPCHS-CCPCHPICHAICHPDSCHDPCH
S-CCPCH,k = N x 256 chips
DPCH,n = N x 256 chips
PICH = 7680 chips (3 slots)
3GPP TS 25.211 ¶ 7.03GPP TS 25.211 ¶ 7.0
k:th S-CCPCH
PICH for n:th S-CCPCH
n:th DPCCH/DCDPH
Downlink Shared Channel
Dedicated PhysicalControl/Data Channel
Part 5: 4 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Downlink Scrambling Codes• Downlink Scrambling Codes
Used to distinguish Base Station transmissions on Downlink Each Cell is assigned one and only one Primary Scrambling Code
The Cell always uses the assigned Primary Scrambling Code for the Primary and Secondary CCPCH’s
Secondary Scrambling Codes may be used over part of a cell, or for other data channels
Primary SC0
Secondary Scrambling
Codes
(15)
Secondary Scrambling
Codes
(15)
Secondary Scrambling
Codes
(15)
Secondary Scrambling
Codes
(15)
Code Group #1 Code Group #64
8192 Downlink Scrambling CodesEach code is 38,400 chips of a 218 - 1 (262,143 chip) Gold Sequence
3GPP TS 25.213 ¶ 5.2.23GPP TS 25.213 ¶ 5.2.2
Primary SC7 Primary SC504Primary SC511
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Downlink Scrambling Codes• Downlink Scrambling Code Generation
10 mSec Gold Code formed by Modulo-2 Addition of 38,400 chips from two m-sequences
Initial Conditions:
x(0) =1; X(1)... X(17) = 0y(0) ... Y(17) = 1
I
Q
1
1 0
02
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
17
17
16
16
15
15
14
14
13
13
12
12
11
11
10
10
X
Y
3GPP TS 25.213 ¶ 5.2.23GPP TS 25.213 ¶ 5.2.2
Primary Scrambling code i (where i = 0,...,511) is generatedby offsetting the X sequence by (16*i) clock cycles from the Y sequence
Primary Scrambling code i (where i = 0,...,511) is generatedby offsetting the X sequence by (16*i) clock cycles from the Y sequence
Part 5: 6 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Synchronization Codes• Synchronization Codes (PSC, SSC)
Broadcast by BS
First 256 chips of every SCH time slot
Allows UE to achieve fast synchronization in an asynchronous system
Primary Synchronization Code (PSC)
Fixed 256-chip sequence with base period of 16 chips
Provides fast positive indication of a WCDMA system
Allows fast asynchronous slot synchronization
Secondary Synchronization Codes (SSC)
A set of 16 codes, each 256 bits long
Codes are arranged into one of 64 unique permutations
Specific arrangement of SSC codes provide UE with frame timing, BS “code group”
P-CCPCH
(PSC + SSC + BCH)2304 Chips256 Chips
3GPP TS 25.213 ¶ 5.2.33GPP TS 25.213 ¶ 5.2.3
Broadcast Data (18 bits)SSCi
PSC
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Primary Synchronization Code
• Primary Synchronization Code (PSC)
let a = <1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1>
PSC(1...256) = < a, a, a, -a, -a, a, -a, -a, a, a, a, -a, a, -a, a, a >
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 Frame = 15 slots = 10 mSec
Note: PSC is transmitted “Clear” (Without scrambling)
3GPP TS 25.213 ¶ 5.2.33GPP TS 25.213 ¶ 5.2.3
Broadcast Data (18 bits)SSCi
2304 Chips256 ChipsSCH BCH
PSC
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Secondary Synchronization Code Group
• 16 Fixed 256-bit Codes; Codes arranged into one of 64 patterns
slot number Scrambling Code Group
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15
Group 1 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16
Group 2 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10
Group 3 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12
Group 62 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11
Group 63 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16
Group 64 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10
Note:
The SSC patterns positively identify one and only one of the 64 Scrambling Code Groups.
This is possible because no cyclic shift of any SSC is equivalent to any cyclic shift of any other SSC.
3GPP TS 25.213 ¶ 5.2.33GPP TS 25.213 ¶ 5.2.3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 Frame = 15 slots = 10 mSec
SSC1 SSC2 SSC3 SSC4 SSC5 SSC6 SSC7 SSC8 SSC9 SSC10 SSC11 SSC12 SSC13 SSC14 SSC15 SSC16
SSCi
SSC1 SSC15
Part 5: 9 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Slot Synchronization
• Slot Synchronization using Primary Synchronization Code
BCH Data
PSC[1]
BCH Data
PSC[2]
BCH Data
PSC[3]
BCH Data
PSC[4]
BCH Data
PSC[15]
Matched Filter(Matched to PSC)
10 mSec Frame (15 slots x 666.666 uSec)
MatchedFilterOutput
time
P-CCPCH
(PSC)
3GPP TS 25.214 Annex C3GPP TS 25.214 Annex C
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Frame Synchronization, SCG ID
• Frame Synchronization using Secondary Synchronization Code
BCH Data
SSC[1]
BCH Data
SSC[2]
BCH Data
SSC[3]
BCH Data
SSC[4]
BCH Data
SSC[15]
Matched Filter
Matched to SSC code group pattern
10 mSec Frame (15 slots x 666.666 uSec)
MatchedFilterOutput
time
SSC[2]
SSC[3]
SSC[4]
SSC[1]
SSC[6]
SSC[7]
SSC[8]
SSC[5]
SSC[10]
SSC[11]
SSC[12]
SSC[9]
SSC[14]
SSC[15]
SSC[13]
SSC Code Group Pattern provides
• Frame Synchronization
• Positive ID of Scrambling Code Group
Remember, no cyclic shift of any SSC is equal to any other SSC
3GPP TS 25.214 Annex C3GPP TS 25.214 Annex C
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Random Access
• Random Access Attempt and AICH Indication
Pre-amble
Pre-amble
Pre-amble
AICH
RACH
NoInd.
NoInd.
Acq.Ind.
RACH
message part(UE Identification)UE
BS
3GPP TS 25.211 ¶ 7.33GPP TS 25.211 ¶ 7.3
4096 chips(1.066 msec)
Part 5: 12 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Random Access Procedure
• Prior to initiating a Random Access attempt, the UE receives:
The preamble spreading code for this cell
The available random access signatures
The available spreading factors for the message part
The message length (10 ms or 20 ms)
Initial preamble transmit power
Power ramping factor
The AICH transmission timing parameter
The power offset DPp-m between preamble and the message part.
Transport Format parameters
3GPP TS 25.214 ¶ 6.13GPP TS 25.214 ¶ 6.1
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Random Access Preamble Signatures
Random Access Preamble Signature Symbols
Signature P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 2 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 3 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 4 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 5 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 6 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 7 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 8 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 9 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 10 1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 11 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 12 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1 13 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1 14 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1 15 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1
• Preamble codes are 16-long Orthogonal Walsh Codes.
• Preamble = [ P0, P1, … P15 ] repeated 256 times (4096 chips total).
• Preamble codes help the BS distinguish between UE making simultaneous Random Access Attempts.
3GPP TS 25.213 ¶ 4.3.3.33GPP TS 25.213 ¶ 4.3.3.3
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Random Access Scrambling Codes
• Random Access Preamble Scrambling Codes
Preamble Scrambling Code is a 4096-chip segment of a 225-long Gold Code
The UE targets one BS by using the BS’s indicated preamble scrambling code
“All UE accessing this cell shall use Random Access Preamble Spreading Code
n2 ”
“All UE accessing this cell shall use Random Access Preamble Spreading Code
n1 ”
3GPP TS 25.213 ¶ 4.3.33GPP TS 25.213 ¶ 4.3.3
Part 5: 15 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Acquisition Indication Channel
• Acquisition Indication Channel (AICH)
Transmits Acquisition Indicators in response to UE Access Attempts
AI’s are derived from the UE’s Access Preamble Signature
Identifies the UE which is the target of the AICH response
1024 chips
AS #0 AS #1 AS #i AS #14
a1 a2a0 a31a30
AI part
20 ms
AS #14 AS #0
(Transmission Off)
15
0,
sjssj bAIa
3GPP TS 25.211¶ 5.3.3.63GPP TS 25.211¶ 5.3.3.6
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Random Access Message
• Random Access Message
Sent only after positive AICH indication
3GPP TS 25.211¶ 5.2.23GPP TS 25.211¶ 5.2.2
Random Access Message (10, 20, 40, or 80 bits per slot)
RACH Data Slot (0.666 mSec)
Pilot (8 bits)
RACH Message Slot (0.666 mSec)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 Frame = 15 slots = 10 mSec
I
QTFCI (2 bits)
Part 5: 17 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Random Access Offset Timing• Random Access Procedure
Available RACH time slots determined by upper layers, sent over BCHUE selects slot based on pseudo-random algorithm
#0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14
5120 chips
radio frame: 10 ms radio frame: 10 ms
Access slot #0 Random Access Transmission
Access slot #1
Access slot #7
Access slot #14
Random Access Transmission
Random Access Transmission
Random Access TransmissionAccess slot #8
P PP Message
= Random Access Transmission
3GPP TS 25.211 ¶ 5.2.2.1.13GPP TS 25.211 ¶ 5.2.2.1.1
Part 5: 18 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Acquisition and Synchronization
• Physical Layer Procedures
1) UE Acquisition and Synchronization
Initiate Cell Synchronization
P-CCPCH
(PSC + SSC + BCH)
UE Monitors Primary SCH code, detects peak in matched filter output
Slot Synchronization Determined ------>
UE Monitors Secondary SCH code, detects SCG and frame start time offset
Frame Synchronization and Code Group Determined ------>
UE Determines Scrambling Code by correlating all possible codes in group
Scrambling Code Determined ------>
UE Monitors and decodes BCH data
BCH data, Super-frame synchronization determined ------>
Cell Synchronization Complete
UE adjusts transmit timing to match timing of BS + 1.5 Chips
Part 5: 19 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Random Access
• Physical Layer Procedures
2) UE Requests System Access and Registration
Cell Synchronization Complete
P-CCPCH
(PSC + SSC + BCH)
UE Reads Random Access parameters from BS;Calculates Random Access probe power
Initiate Random Access Attempt; Respond to Authentication challenge
When system Registration is complete, UE enters Idle mode
Part 5: 20 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Establishing a Dedicated Channel
• Physical Layer Procedures
3) Establishing a Dedicated Channel
UE in Idle Mode
BS Begins transmission of downlink DPCCH/DPDCH
UE Establishes chip and frame sync to UTRAN
UE begins transmission of Reverse Link Channel,Responds to TPC bits from BS
UTRAN establishes Reverse Link chip and frame sync,Responds to TPC bits from UE
UE and BS notify upper layers that synchronization is complete
Dedicated Channel Established
3GPP TS 25.214 ¶ 4.3.23GPP TS 25.214 ¶ 4.3.2
Part 5: 21 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Packet Channel AccessAICHDPCCH
3GPP TS 25.211 ¶ 7.43GPP TS 25.211 ¶ 7.4
CCCTFCITPC Pilot
FBITFCI TPCPilot
DPDCH (Data); SF 4 to 256
DL-DPCCH Slot (SF=256)
DPCCH Slot (SF=256)
CPCHDPCCHDPDCH
CCC (CPCH Control Commands)e.g., Start-of-Message , Emergency-Stop
PCPCHUplink Data Packet
‘N’ x 10 msec FramesPower Control
Preamble(0 or 8 slots)
FBITFCI TPCPilot
PCPH PC-Preamble Slot (SF=256)
CSICH
APAP
AP-AICH CD/CA-ICH
CDP
Part 5: 22 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Packet Channel Access
• Prior to Packet Access, the UE receives from the UTRAN:
UL Access Preamble (AP) scrambling code.
UL Access Preamble signature set.
The Access preamble slot sub-channels group.
AP- AICH preamble Channelization code.
UL Collision Detection(CD) preamble scrambling code.
CD Preamble signature set.
CD preamble slot sub-channels group.
CD-AICH preamble Channelization code.
CPCH UL scrambling code.
DPCCH DL Channelization code.([512] chip).
CSICH/CA message indicating channel availability
3GPP TS 25.211 ¶ 7.43GPP TS 25.211 ¶ 7.4
Part 5: 23 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
CPCH Status Indication Channel
• CPCH Status Indication Channel (CSICH)
Transmits Indicators to convey PCPH Channel Availability
1024 chips8 bits/slotSF = 256
AS #0 AS #1 AS #i AS #14
b1 b2b0
4096 chips
20 ms
AS #14 AS #0
(Transmission Off)
3GPP TS 25.211¶ 5.3.3.63GPP TS 25.211¶ 5.3.3.6
b4 b5b3 b7b6
Higher layers provide mapping of status indicators to availability of CPCH resources
Part 5: 24 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Access Preamble Indication Channel
• Access Preamble Indication Channel (AP-AICH)
Transmits Indicators in response to UE CPCH Access Attempt
API’s are derived from the UE’s CPCH Access Preamble Signature
Identifies the UE which is the target of the AP-AICH response
1024 chips
AS #0 AS #1 AS #i AS #14
a1 a2a0 a31a30
20 ms
AS #14 AS #0
(Transmission Off)
15
0,
sjssj bAPIa
3GPP TS 25.211¶ 5.3.3.63GPP TS 25.211¶ 5.3.3.6
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CD/CA Indication Channel
• Collision Detection/Channel Assignment Indication Channel
Transmits Acquisition Indicators in response to UE CD preambles
CDI’s are derived from the UE’s CD Preamble Signature
Optionally may transmit CPCH Channel Assignment Indicators
1024 chips
AS #0 AS #1 AS #i AS #14
a1 a2a0 a31a30
20 ms
AS #14 AS #0
(Transmission Off)
15
0,
15
0,
sjss
sjssj bCAIbCDIa
3GPP TS 25.211¶ 5.3.3.63GPP TS 25.211¶ 5.3.3.6
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WCDMA Soft Handover
Destination BSOriginating BS SC5 SC6
SC1
SC4SC7 SC8
• Each cell uses a different Scrambling Code
• Each cell has an independent time reference
• CPICH and System Frame timing between cells is arbitrary
Part 5: 27 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
The WCDMA Soft Handover Problem...
• WCDMA Base Stations have Asynchronous timing references IS-95/cdma2000 BS’s are synchronized to GPS!
Data 2TFCIData 1 TPC
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Pilot
CPICH 2CPICH 2CPICH 2
CPICH 1CPICH 1CPICH 1
DPCCH/DPDCHDPCCH/DPDCHDPCCH/DPDCH
CPICH 2
CPICH 1
DPCCH/DPDCH
Toffset
10 msecframe
BS 1
BS 2
DPCCH/DPDCHDPCCH/DPDCHDPCCH/DPDCH DPCCH/DPDCH
10 msec DPCCH/DPDCH frame
0.666 msec DPCCH/DPDCH slot
Part 5: 28 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Handover Scenarios
RNS
RNC
RNS
RNC
Node B Node B Node B Node B
Iu Iu
Iur
Iub IubIub Iub
Inter-Node(Hard or Soft)
Intra-Node(Softer)
Inter-RNS(Soft with Iur;
Hard with no Iur)
UTRAN
Core Network
3GPP TS 25.8323GPP TS 25.832
Part 5: 29 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Soft Handover
• To facilitate asynchronous handover, timing adjustments are made by the UE, the RNC, and the Core Network
TimeAlignment
Transport ChannelFrame Alignment
RadioSynchronization
RNS
UTRAN
Core Network
UE
RNS
Node B
Node B
Node B
Vocoder
Node B
Node B
Node B
RNCRNC
3GPP TS 25.401 ¶ 9.03GPP TS 25.401 ¶ 9.0
Part 5: 30 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Soft Handover• Soft Handover Initiation
(2)
UE measures CPICH power and time delay
from adjacent cells
(3)
UE Reports measurements to UTRAN
(1)
UTRAN informs UE of neighboring cell
information
(4)
UTRAN decides the handover
strategy
CPICH 2CPICH 2CPICH 2
CPICH 1CPICH 1CPICH 1
DPCCH/DPDCHDPCCH/DPDCHDPCCH/DPDCH
CPICH 2
CPICH 1
DPCCH/DPDCH
Toffset
10 msecframe
BS 1
BS 2
UTRAN
UE Reports Toffset
to UTRAN
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WCDMA Soft Handover
(6)
UE Rake Receiver Synchronizes to BS2
DPCCH/DPDCH
(7)
UE in soft handover with BS1 and BS2 DPCCH/DPDCH’s
(5)
UTRAN Commands BS2 to adjust DPCH timing by
Toffset
(8)
When BS2 sufficiently strong, drop BS1.
(Handover complete)
CPICH 1CPICH 1CPICH 1
DPCCH/DPDCHDPCCH/DPDCHDPCCH/DPDCH
CPICH 2CPICH 2CPICH 2CPICH 2
CPICH 1
DPCCH/DPDCH
Toffset
10 msecframe
BS 1
BS 2
UTRAN
UE Reports Toffset
to UTRAN
UTRAN Commands BS2to adjust DPCH timing
by Toffset
DPCCH/DPDCHDPCCH/DPDCHDPCCH/DPDCH DPCCH/DPDCH
Toffset
• Soft Handover Execution
Part 5: 32 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Inter-Frequency Handover
• Inter-frequency Handover
To allow inter-frequency measurements, data is compressed in time so that some of the 10 mSec frame is available for measurements.
8 to 14 slots per frame may be used
Data compression can be accomplished by:
Decreasing the Spreading Factor by 2:1
– Increases Data Rate so bits get through twice as fast!
Puncturing bits
– weakens FEC coding
Higher layer scheduling
– Reduces available timeslots for user traffic
Part 5: 33 of 345/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Compressed Mode Operation• 1 to 7 slots per frame diverted for hard handover processes
3GPP TS 25.212 ¶ 4.4.33GPP TS 25.212 ¶ 4.4.3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 151 2 3 4 511 12 13 14 15 6
1 2 3 4 5 11 12 13 14 151 2 3 4 511 12 13 14 15 6
1 2 3 4 5 6 7 8 9 10 11 12 4 511 12 13 14 15 6
10 mSec Frames (15 slots)
Normal Operation
Compressed-Mode; single-frame method
Compressed-Mode; double-frame method
Transmission Gap
Transmission Gap
The complete TFCI word must be transmitted every frame, even in Compressed Mode.Compressed Mode Slot formats (A,B) contain higher proportion of TFCI bits per slot compared with normal slots.
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Handover to/from GSM
• Handover to/from GSM
GSM handover is an explicit requirement in WCDMA
Facilitated by commonality of multi-frame structures
1 2 3 4 5 6 7 8 9 10 11 12
T T T T T T T T T T T S T T T T T T T T T T T T T I
12 WCDMA 10 mSec Frames (120 ms)
GSM 26-frame TCH multiframe (120 ms)
T = Traffic FrameS = SACCH FrameI = Idle Frame