An Introduction to CDMA Air Interface: TIA/EIA/IS-95A
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Transcript of An Introduction to CDMA Air Interface: TIA/EIA/IS-95A
An Introduction to CDMA Air Interface: TIA/EIA/IS-95A
Advanced Technology Center
Computer & Communications Research Laboratories
Industrial Technology Research InstituteRay-Guang Cheng
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Contents
• Introduction
• Forward CDMA Channel
• Reverse CDMA Channel
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CDMA Around the World
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Multiple Access
• FDMA– Advanced Mobile Phone Service (AMPS) and Total Access Communicat
ions System (TACS)
– AMPS systems use 30 kHz "slices" of spectrum for each channel
– Narrowband AMPS (NAMPS) requires only 10 kHz per channel
– TACS channels are 25 kHz wide
• TDMA– IS-54 systems, designed to coexist with AMPS systems, divide 30 kHz o
f spectrum into three channels
– PDC divides 25 kHz slices of spectrum into three channels
– GSM systems create 8 time-division channels in 200 kHz wide carriers
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Multiple Access
• CDMA – unique digital codes are used to differentiate subscribers
– codes are shared by both MS and BS
– all users share the same range of radio spectrum
• Benefits of CDMA:– Capacity increases: 8 to 10 times (AMPS); 4 to 5 times (GSM)
– Improved call quality
– Simplified system planning
– Enhanced privacy
– Improved coverage characteristics
– Increased talk time for portables
– Bandwidth on demand
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CDMA
• There are two CDMA common air interface standards:– Cellular (824-894 MHz) - TIA/EIA/IS-95A– PCS (1850-1990 MHz) - ANSI J-STD-008
They are very similar in their features, with exceptions of the frequency plan, mobile identities, and related message fields.
• IS-95A– 45 MHz spacing for forward & reverse channel– Permissible frequency assignments are on 30 kHz increments– W/R = 10 log (1.2288 MHz/9600Hz) = 21 dB for the 9600 bps rate set
• ANSI J-STD-008– 80 MHz spacing for forward & reverse channel– Permissible frequency assignments are on 50 kHz increments
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Frequency Plan of IS-95A
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Frequency Plan of ANSI J-STD-008
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Forward CDMA Channel of IS-95A
• From BSS to MS
• It carries traffic, a pilot signal, and overhead information.
• Pilot is a spread but unmodulated DSSS signal.
• Pilot and overhead channels establish the system timing and station identity.
• Pilot channel is also used in the mobile-assisted handoff (MAHO) process as a signal strength reference.
• FEC code rate is 1/2 and the PN rate is 1.2288 MHz (1.2288 MHz = 128*9600 bps).
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Forward Link Channel Parameters
Channel Sync Paging Traffic
Data rate 1200 4800 9600 1200 2400 4800 9600 bps
Code repetition 2 2 1 8 4 2 1
Modulation symbol rate 4800 19,200 19,200 19,200 19,200 19,200 19,200 sps
PN chips/modulation symbol 256 64 64 64 64 64 64
PN chips/bit 1024 256 128 1024 512 256 128
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Signal Structure
• The forward link consists of up to 64 logical channels (code channels).
• Code channels is one of a set of 64 so-called Walsh functions.
• Only whole periods of the Walsh functions occur in each code symbol, the Walsh makes the channels completely separable in the receiver.
• Each forward code channel is spread by the Short Code, which has I- and Q-components.
• The two coded, covered, and spread streams are vector-modulated on the RF carrier. The spreading modulation is thus QPSK, superimposed on a BPSK code symbol stream.
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Overhead Channels
• There are three types of overhead channel in the forward link:– pilot, is required in every station
– sync
– paging
• Pilot channel– pure short code with no additional cover or information content
– always code channel zero
– a demodulation reference for the mobile receivers and for handoff level measurements
– carries no information
– all stations use the same short code, distinguished by the phase
– period of the short code, 215= 26.667 ms at the 1.2288 MHz chip rate
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Overhead Channels
• Pilot channel (Conti.)– pilot phases always be assigned to stations in multiples of 64 chips, givin
g a total of 215-6 = 512 possible assignments
– 9-bit number that identifies the pilot phase assignment is called the Pilot Offset
• Sync Channel– sync channel carries timing and system configuration information
– data rate is always 1200 bps
– interleaver period is also 80/3 = 26.667 ms, simplifies finding frame boundaries, once the mobile has located the pilot
– code period ambiguity is then resolved by the long code state and system time fields
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Overhead Channels
• Paging channel– used to communicate with MSs when they are not assigned to a traffic ch
annel
– successful accesses are normally followed by an assignment to a dedicated traffic channel
– paging channel may run at either 4800 or 9600 bps
– each BS must have at least one paging channel per sector, on at least one of the frequencies in use
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Traffic Channel
• Traffic channels – assigned dynamically, in response to MS accesses, to specific MS
– always carries data in 20 ms frames– carry variable rate traffic frames, either 1, 1/2, 1/4, or 1/8 of 9600 bps
– rate variation is accomplished by 1, 2, 4, or 8-way repetition of code symbols, but the energy per bit approximately constant
– rate is independently variable in each 20 ms frame
– the 800 bps reverse link power control subchannel is carried on the traffic channel by puncturing 2 from every 24 symbols transmitted.
• Timing– all base stations must be synchronized within a few microseconds
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Reverse CDMA Channel of IS-95
• From MS to BSS
• It carries traffic and signaling information.
• FEC code rate is 1/3, the code symbol rate = 28,800 symbols/sec, 6 code symbols/modulation symbol, and the PN rate is 1.2288 MHz
• modulation is 64-ary orthogonal Walsh functions, each period of the Walsh function is repeated for four chips of the PN code
• Walsh symbol rate is 1.2288 MHz/(4 chips per Walsh chip)/(64 Walsh chips per Walsh symbol) = 4,800 modulation symbols/ second
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Reverse CDMA Channel Parameters, Rate Set 1
Channel Access Traffic
Data rate 4,800 1,200 2,400 4,800 9,600 bps
Code Rate 1/3 1/3 1/3 1/3 1/3
Symbol Rate before Repetition 14,400 3,600 7,200 14,400 28,800 sps
Symbol Repetition 2 8 4 2 1
Symbol Rate after Repetition 28,800 28,800 28,800 28,800 28,800 sps
Transmit Duty Cycle 1 1/8 1/4 1/2 1
Code Symbols/Modulation Symbol 6 6 6 6 6
PN Chips/Modulation Symbol 256 256 256 256 256
PN chips transmitted/bit 256 128 128 128 128
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Signal Structure
• Reverse CDMA Channel consists of 2 42-1 logical channels
• One of the logical channel is permanently and uniquely associated with each MS. The channel does not change upon handoff.
• Reverse link addressing is accomplished through manipulation of period 2 42-1 Long Code, which is part of the spreading process.
• The reverse CDMA Channel does not use strict orthogonality in any sense to separate logical channels. Rather, it uses a very long period spreading code, in distinct phases. The correlations between stations are not zero, but they are acceptably small.
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Handoff
• CDMA is specifically designed not only to reduce handoff failures but also to provide seamless service.
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Handoff
• Steps in a handoff– Starting in a state where only one cell is supporting the call in question.
– Informing the candidate cell of the imminent handoff
– Signaling the mobile to begin executing the handoff.
– New cell beginning to service the mobile
– Mobile beginning to use the new cell
– Entering the mid-handoff state (prolonged only in CDMA)
– Mobile discontinuing use of the old cell
– Old cell stopping service to the mobile
– Ending in a state where the new cell is supporting the call in question
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AMPS v.s. CDMA
• Difference between AMPS & CDMA– CDMA handoffs do not normally require frequency tuning.
– CDMA requires change of the code channel in the forward CDMA channel.
– No tuning, either frequency or code channel is required in the reverse CDMA channel at any time.
• AMPS– Hard handoff (communication is interrupted briefly)
– not simultaneous communication with more than one BS
– BS do the signal quality measurement
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CDMA Protocol
Upper Layers(Primary Traffic)
Upper Layers(Secondary Traffic)
Layer 2(Primary Traffic)
Layer 2(Secondary Traffic)
Layer 2(Signaling)
Multiplex Sublayer (Traffic Channel)
Layer 2(Link Layer)
Paging & AccessChannels
Layer 2Sync
Channels
Layer 3 (Mobile Station Control Processes)
Layer 1 (Physical Layer)
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Multiplex Option Information
Format Bits PrimaryTraffic
SignalingTraffic
SecondaryTraffic
TransmitRate(bps)
MixedMode (MM )
TrafficType (TT )
TrafficMode( TM )
Bits/frame Bits/frame Bits/frame
0 - - 171 0 01 0 00 80 88 01 0 01 40 128 01 0 10 16 152 01 0 11 0 168 01 1 00 80 0 881 1 01 40 0 1281 1 10 16 0 152
9600
1 1 11 0 0 1684800 - - - 80 0 02400 - - - 40 0 01200 - - - 6 0 0
Format Bits PrimaryTraffic
SignalingTraffic
SecondaryTraffic
TransmitRate(bps)
MixedMode (MM )
TrafficType (TT )
TrafficMode( TM )
Bits/frame Bits/frame Bits/frame
0 - - 171 0 01 0 00 80 88 01 0 01 40 128 01 0 10 16 152 01 0 11 0 168 01 1 00 80 0 881 1 01 40 0 1281 1 10 16 0 152
9600
1 1 11 0 0 1684800 - - - 80 0 02400 - - - 40 0 01200 - - - 6 0 0
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Primary and Signaling Traffic
MM=0
MM=1
MM=1
MM=1
MM=1
TT=0
TT=0
TT=0
TT=0
TM=00
TM=01
TM=10
TM=11
Primary Traffic = 171 bits
Primary Traffic = 80 bits
Signaling Traffic = 88 bits
Primary Traffic = 40 bits
Signaling Traffic = 128 bits
Primary Traffic = 16 bits
Signaling Traffic = 152 bits
Signaling Traffic = 168 bits
Primary Traffic = 80 bits
Primary Traffic = 40 bits
Primary Traffic = 16 bits
9600 bps Primary Traffic only
Dim & Burst with rate 1/2primary & signaling traffic
Dim & Burst with rate 1/4primary & signaling traffic
Dim & Burst with rate 1/8primary & signaling traffic
Blank & Burst withsignaling traffic only
4800 bps primarytraffic only
2400 bps primarytraffic only
1200 bps Primarytraffic only
172 bits
80 bits
40 bits
16 bits
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Secondary Traffic
MM=1
TT=1
TM=00
Primary Traffic = 80 bits
Signaling Traffic = 88 bits
MM=1
TT=1
TM=01
Primary Traffic = 40 bits
Signaling Traffic = 128 bits
MM=1
TT=1
TM=10
Primary Traffic = 16 bits
Signaling Traffic = 152 bits
MM=1
TT=1
TM=11
Signaling Traffic = 168 bits
Dim & Burst with rate1/2 primary &
Secondary traffic
Dim & Burst with rate1/4 primary &
Secondary traffic
Dim & Burst with rate1/8 primary &
Secondary traffic
Blank & Burst withSecondary traffic only
172 bits
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Sync Channel
• Signaling on all channels use a synchronized bit-oriented protocol.
• Sync channel is used during the system acquisition stage.
• Sync channel frame length is the length of pilot PN sequence.
• Only the Sync Channel Message is sent on the sync channel.
• MS – obtains information from Sync Channel Message
– adjusts its timing to normal system timing
– begins monitoring its Paging Channel
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Paging Channel
• Data rate: 2400, 4800, 9600 bps
• One 9600 bps Paging Channel can support 180 pages/sec.
• Paging Channel conveys four major types of messages:– overhead– paging– order– channel assignment
• Configuration of the system is conveyed in four overhead messages:– System Parameter Message– Access Parameter Message– Neighbor List Message– CDMA Channel List Message
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Overhead Messages
• System Parameter Message:– configuration of the Paging Channel– registration parameters– parameters to aid pilot acquisition
• Access Parameter Message– configuration of the Access Channel– control parameters used to stabilize the Access Channel
• Neighbor List Message– time offset of the pilot– basic neighbor configuration
• CDMA Channel List Message– CDMA frequency assignment that contain Paging Channels
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Paging Channel Messages
• Page Message: – contains pages to one or more mobile stations.
• Order Message: – a broad class of messages used to control a particular MS.
• Channel Assignment Message:– let BS to assign a MS to the traffic channel
– change Paging Channel Assignment
– direct the MS to use the analog FM system
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Access Channel
• Access Channel provides communications from MS to BS when MS is not using a Traffic Channel.
• All Access Channel use 4800 bps mode
• Access Channel Message:– call origination
– response to pages
– orders
– registrations
• One or more Access Channel are paired with every Paging Channel
• Control of Access Channel transmission is accomplished through the Access Parameter Message sent on the Paging Channel
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Framing and Signaling on the Traffic Channel
• Both forward & reverse Traffic Channels use 20 ms frames.
• Frames can be sent at 9600, 4800, 2400, or 1200 bps
• Signaling– blank-and-burst signaling:
• sent at 9600 bps
• replace one or more frames of primary traffic data
– dim-and-burst signaling:
• sent at 9600 bps
• sends both signaling and primary traffic data in a frame
• degradation in voice quality is essentially undetectable
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Traffic Channel Messages & Service Option
• Four types of control messages on the Traffic Channel– messages controlling the call itself
– messages controlling handoff
– messages controlling forward link power
– messages for security and authentication
• IS-95 supports different user applications, called service options
• Two different service options can be simultaneous supported:– primary traffic
– secondary traffic
• MS can specify the desired service option at call origination.
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IS-95 Standard
• Forward Link– Pilot Channel
– Sync Channel
– Paging Channels (max. 7)
– Traffic Channels• Power Control Sub-Channel
• Reverse Link– Access Channels
– Traffic Channels
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Forward CDMA Channel
• Forward link consists of up to 64 logical channels (code channels)• The code channels are distinguished by a set of 64 Walsh
functions• Walsh function code number zero is always reserved as the pilot• Short Code (with period 215, 27.667 ms at 1.2288 MHz)
– spreading the CDMA Forward Channel– used in conjunction with the Long Code for spreading the CDMA Reverse
Channel
• Long Code (with period 242 - 1)– spreading the CDMA Reverse Channel– Long Code Mask serves as a reverse link address
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Generation of Forward Code Channel
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Forward Channel Modulator (Spreading)
• Identical I, Q signals; but different I, Q PN sequences (short code)
• Transmitted power is reduced by 3, 6, or 9 dB for variable data rates at 9.6 k, 4.8 k, 2.4 k, and 1.2 kbps
• QPSK modulation
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Forward Link Modulation Parameters
• 64 othoronal Walsh codes per sector to identify channels– (S/N is not infinite due to AWGN, multipath, and the neighboring cell)
• Long code (period 2 42 -1) to scramble data
• DS at 1.2288 Mcps
• Every cell uses the same PN sequence (period 2 15 or 26.67ms) and is identified by a pre-defined offset (64 x n chips)
• Coherent QPSK demodulation
• Diversity– time diversity: coding + interleaving
– path diversity: soft handoff and RAKE receiver
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Logical Forward CDMA Channel
Forward CDMA Channel
PilotChan
SyncChan
W0 W32
PagingCh 1
W1
...Upto W7
PagingCh 7
W8
...Upto
TrafficCh N
TrafficCh 1
Traffic Data Mobile PowerControl Sub-Channel
...W31
TrafficCh 24
Upto
...W63
TrafficCh 55
W33
TrafficCh 25
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Pilot Channel
• Unmodulated signal
• Unique per sector/cell
• Signal level is 4~6 dB higher than traffic channel
• Perfect phase/time/signal strength reference for MS
• Used in initial system acquisition and handoff for MS
PilotChannel(All 0’s)
Walsh Function
W0PN Chips
1.2288 Mcps
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Sync Channel
• 1200 bps
• To convey pilot PN sequence offset, time of day, and long code state to allow immediate sync of MS to the network
SyncChannel
Bits 1.2 kbps
ConvolutionalEncoder
R=1/2, K=9
CodeSymbol
2.4 ksps
SymbolRepetition
BlockInterleaver
ModulationSymbol
4.8 ksps
ModulationSymbol
4.8 ksps
Walsh Function
W32
PN Chips 1.2288 Mcps
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Sync Channel Frame Structure
• Sync channel message has length of 93 x N bits
• Sent in N superframes:– 1 superframe (96 bits, 80 ms) = 3 sync channel frames
– 1 frame (32 bits, 26.67 ms) = 1-bit SOM + 31-bit data
– SOM = 1 : start of message
• Message contains:– system identification (SID) and network identification (NID)
– PN sequence offset and long code state
– system time, leap seconds, offset from UTC, etc.
– paging channel data rate
MessageLength
(in bytes)
8 bits
Data
N MSG = 2 ~ 1146 bits
CRC
30 bits
Padding= …000...
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Paging Channels
• 4.8 k or 9.6 k bps
• Same time alignment as the traffic channels
• To page MS and to process other orders
PagingChannel
Bits 4.8 kbpsor
9.6 kbps
ConvolutionalEncoder
R=1/2, K=9
CodeSymbol
9.6 kspsor
19.2 ksps
SymbolRepetition
BlockInterleaver
ModulationSymbol
19.2 ksps
ModulationSymbol
19.2 ksps
Walsh Function
W p1 p 7
PN Chips 1.2288 Mcps
Long CodeMask forPaging
Channel p
Long CodeGenerator
1.2288 McpsDecimator
19.2 ksps
19.2 ksps
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Paging Channel Frame Structure
• Synchronized paging channel message has length of 47 x N or 95 x N bits
• Sent in N paging channel slots:– 1 slot (80 ms) = 8 paging channel half-frames
– 1 half-frame (10 ms, 48 or 96 bits) = 1-bit SCI + 47 (or 95)-bit data
– SCI = 1 : start of a paging channel message
• Message contains:– system parameters
– access parameter (for access channel)
– channel assignment
– TMSI (temporary MS identification) assignment
MessageLength
(in bytes)
8 bits
Data
N MSG = 2 ~ 1146 bits
CRC
30 bits
Padding= …000...
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Forward Traffic Channels
• 9.6, 4.8, 2.4, or 1.2 k bps; 20 ms frames
• Rate can be changed every frame
Forward TrafficChannel
InformationBits for User m(172, 80, 40 or16 bits/frame)
8.6 kbps4.0 kbps2.0 kbps0.8 kbps
ConvolutionalEncoder
R=1/2, K=9
SymbolRepetition
BlockInterleaver
ModulationSymbol
19.2 kspsModulation
Symbol
19.2 ksps
Add Frame Quality Indicator
for 9600 &4800 bps Rates
Add 8-bitEncoder
Tail9.2 kbps4.4 kbps2.0 kbps0.8 kbps
9.6 kbps4.8 kbps2.4 kbps1.2 kbps
19.2 kbps 9.6 kbps 4.8 kbps 2.4 kbps
Long CodeMask forPaging
Channel p
Long CodeGenerator
1.2288 Mcps
Decimator
19.2 ksps Walsh Function
W m
PN Chips 1.2288 Mcps
Decimator
MUX
PowerControl
Bits800 bps
800 Hz
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Forward Traffic Channel Frame Structure
8
T
12
F
172
information bits
192 bits (20 ms)9600 bpsFrame
8
T
8
F
80
information bits
96 bits (20 ms)4800 bpsFrame
8
T
8
F
40
information bits
48 bits (20 ms)2400 bpsFrame
8
T
8
F
16
information bits
24 bits (20 ms)1200 bpsFrame
F: Frame Quality Indicator (CRC)T: Encoder Tail Bits
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Forward Traffic Channel Frame Structure
• For signaling
MessageLength
(in bytes)
8 bits
Data
N MSG = 16 ~ 1160 bits
CRC
16 bits
Padding= …000...
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Logical Reverse CDMA Channel
Reverse CDMA Channel
AccessCh 1
AccessCh n... Traffic
Ch 1TrafficCh m
Address by Long Code PNs
n 32 m 62
…
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Access Channels
• To access the system, respond the page, make call origination and process other messages between the MS and the BS
• 4.8 kbps slotted random access channel
• MS is identified by orthogonal of long codeAccess
ChannelInformation
Bits(88 bits/frame)
4.4 kbps
ConvolutionalEncoder
R=1/3, K=9
CodeSymbol
14.4 ksps
SymbolRepetition
BlockInterleaver
ModulatorSymbol
(Walsh chip)
PN Chips 1.2288 Mcps
Add 8-bitEncoder
Tail 4.8 kbps
CodeSymbol
28.8 ksps
CodeSymbol
28.8 ksps
64-aryOrthogonalModulator Long Code
Generator
Long Code Mask
4.8 ksps
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Long code mask contents
110001111Access Channel
NumberPaging Channel
NumberBase StationIdentification
Pilot Offset for the Forward Channel
1100011000 Permuted ESN
Access Channel Long Code Mask
Reverse Traffic Channel Public Long Code Mask
41 33 32 28 27 25 24 9 8 0
41 32 31 0
ESN=(E31, E30, E29, E28, E27, E26, E25, … , E2, E1, E0)Permuted ESN=(E0, E31, E22, E13, E4, E26, E17, E8, E30, E21, E12, E3, E25, E16, E7, E29, E20, E11, E2, E24, E15, E6, E28, E19, E10, E1, E23, E14, E5, E27, E18, E9)
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Access Channel
AccessChannel
• Is used by the MS to initiate communication with the BS & to respond to Paging Channel message
Fixed data rate (4800 bps) & 20 ms frame duration
•Access Channel Message may carry•Origination of a call • Paging responses•Orders response • Data bursts•Acknowledgements to Paging Channel message•Registration
Information Bits = 88 bitsEncoder Tail
8 bits
96 bits (20 ms)
•Basic frame structure
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Access Channel Frame Structure
• Access channel message has length of 88 x N bits
• Access channel slot is as
– Access channel frame = 88-bits + 8-bit tail bits (all 0s)
– The value of PAM_SZ and MAX_CAP_SZ are received on the paging channel
MessageLength
(in bytes)
8 bits
Data
N MSG = 2 ~ 842 bits
CRC
16 bits
Padding= …000...
Access Channel Preamble = 000…000
96 x (1+PAM_SZ) bits
Access Channel Frame
96 bits
... Access Channel Frame
96 bits
96 x (4+PAM_SZ+MAX_CAP_SZ) bits
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Access Channel Slot Structure
Access ChannelSlot Structure
Is (3+MAX_CAP_SZ)+(1+PAM_SZ) Access Channel frames in length
•An Access Channel slot begins & ends on an Access Channel frame boundary.
•Access Channel slots begin at Access Channel frames in which t mod (4+MAX_CAP_SZ+PAM_SZ)=0 & t: system time in frames
Preamble Max Capsule Size
Access TransmissionMax Length
Access SlotBoundary
20 msAccess channel frame
Access channel slot of five20 ms Access Channel frames
Access Slot n Access Slot n+1 Access Slot n+2
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Access Channel Structure
Access Channel Slot
ACFrame
ACFrame
ACFrame
ACFrame
ACFrame
Access Channel Preamble ACBody
ACBody
ACBody
T T T
Access Channel Message Capsule
Access Channel Message Padding
MSGLength
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
88 Nf bits
Nf frames=96 Nf bits1+ PAM_SZ frame=96 (1+ PAM_SZ)bits
20 ms = 96 bits
0.02 (4+PAM_SZ+MAX_CAP_SZ) sec = 96 (4+PAM_SZ+MAX_CAP_SZ) bits
AC frame = Access Channel frameNf :: Number of Access Channel framesneeded for message transmissionT :: Encoder Tail bits
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field (MSG_Length & CRC)
Access Channel field(MSG_Length & CRC)
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
•The MS set the field of to the length of the message in octets, including the MSG_Length, the message body & the CRC.
•The field shall be 8 bits in length, & the MS shall limit the maximum Access Channel length to 110 octets or 880 bits
• The CRC includes the MSG_Length & the message body. The generator polynomial for the CRC is::
g(x)=X30+X29+X21+X20+X15+X13+X12+X11+X8+X7+X6+X2+1
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field (Message Body)
Access Channel field(Message Body)
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
•Registration Message = “00000001”•Order Message = “00000010”•Data Burst Message = “00000011”•Origination Message = “00000110”•Page Response Message = “00000101”•Authentication Challenge Response Message = “00000110”
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field (Message Body)
Access Channel field(Message Body)
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
•ACK_SEQ:: Acknowledgement Sequence Number • MSG_SEQ:: Message Sequence Number•ACK_REQ:: Acknowledgement Required Indicator • VALID_ACK:: Valid Acknowledgement Indicator•ACK_TYPE:: Acknowledgement Address Type • MSID_TYPE:: MS Identifier field type•MSID_LEN:: MS Identifier field length • MSID:: MS Identifier
8 fields
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field (Message Body)
Access Channel field(Message Body)
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
AUTH_MODE: Authentication modeAUTHR: Authentication dataRANDC: Random Challenge valueCOUNT: Call history parameter
4 fields
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Registration Message
Access Channel field Registration
Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000001
Registration MessageRegistration Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
AUTH_MODE(2 bits)
AUTHR(0 or 18 bits)
RANDC(0 or 8 bits)
COUNT(0 or 6 bits)
REG_TYPE(4 bits)
SLOT_CYCLEINDEX(3 bits)
MOB_P_REV(8 bits)
SCM(8 bits)
MOB_TERM(1 bits)
Reserved(6 bits)
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Order Message
Access Channel field Order Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000010
Order MessageOrder Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
Reversed(2 bits)
Order(6 bits)
ADDR_RECORD_LEN
(3 bits)
Order-specificfield if used
(8 Add_record_len bits)
Reserved(5 bits)
Does NOT have This Field
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Data Burst Message
Access Channel field Data Burst Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000011
Data Burst MessageData Burst Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
AUTH_MODE(2 bits)
AUTHR(0 or 18 bits)
RANDC(0 or 8 bits)
COUNT(0 or 6 bits)
MSG_NUMBER
(8 bits)
Burst_TYPE(6 bits)
NUM_MSGS(8 bits)
SNUM_FIELD(8 bits)
CHARi(8 bits)
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Origination Message
Access Channel field Origination Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000100
Origination MessageOrigination Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
AUTH_MODE(2 bits)
AUTHR(0 or 18 bits)
RANDC(0 or 8 bits)
COUNT(0 or 6 bits)
1(1
bits
)2
(3 b
its)
3(8
bits
)4
(8 b
its)
5(3
bits
)6
(1 b
its)
7(0
or
16 b
its)
8(1
bits
)9
(1 b
its)
10(0
o 3
bits
)11
(0 o
r 4
bits
)12
(1 b
its)
13(8
bits
)14
(4 o
r 8
bits
)15
(1 b
its)
16(0
~7 b
its)
1:: MOB_TERM 2::SLOT_CYCLE_INDEX 3::MOB_P_REV 4::SCM 5::REQUEST_MODE 6::SPECIAL_SERVICE 7::SERVICE_OPATION 8::PM 9:DIGIT_MODE 10::NUMBER_TYPE 11::NUMBER_PLAN 12::MORE_FIELDS 13::NUM_FIELDS 14::CHARi 15::NAR_AN_CAP 16::RESERVED
NUM_FIELDS occurrences of this field
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Page Response Message
Access Channel field Page Response
Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000101
Page Response MessagePage Response Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
AUTH_MODE(2 bits)
AUTHR(0 or 18 bits)
RANDC(0 or 8 bits)
COUNT(0 or 6 bits)
MO
B_
TE
RM
(1 b
its)
SLO
T_C
YC
LE
IND
EX
(3 b
its)
MO
B_
P_R
EV
(8 b
its)
SCM
(8 b
its)
RE
QU
EST
_M
OD
E(3
bit
s)
SER
VIC
E_
OP
TIO
N(1
6 b
its)
PM
(1 b
its)
NA
R_A
N_C
AP
(1 b
its)
RE
SER
VE
D(5
bit
s)
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Access Channel field: Authentication Challenge Response Message
Access Channel field Authentication Challenge
Response Message
Access Channel Message Capsule
Access Channel Message Padding
Message Body CRC
8 bits 2~842 bits 30 bits
8 MSG_Length bits As Required
MSGLength
Message TypeCommon Layer 2 &Identification field
Common Authenticationfield
Reserved or othersas needed
00000110
Authentication Challenge Response MessageAuthentication Challenge Response Message
ACK_SEQ(3 bits)
MSG_SEQ(3 bits)
ACK_REQ(1 bits)
VALID_ACK(1 bits)
ACK_TYPE(3 bits)
MSID_TYPE(3 bits)
MSID_LEN(4 bits)
MSID(8MSID_LEN)
RESERVED(2 bits)
AUTHR(0 or 18 bits)
RESERVED(4 bits)
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Reverse Traffic Channels
• Variable data rates and format are as forward traffic channel. But transmission duty cycle is reduced accordingly. (Bits are not repeated on this channel.)
• Message format is identical to the forward traffic channel.
Reverse TrafficChannel
Information Bits(172, 80, 40 or16 bits/frame)
8.6 kbps4.0 kbps2.0 kbps0.8 kbps
ConvolutionalEncoder
R=1/3, K=9
SymbolRepetition
BlockInterleaver
CodeSymbol
28.8 kspsCode
Symbol
28.8 ksps
Add Frame Quality Indicator
for 9600 &4800 bps Rates
Add 8-bitEncoder
Tail9.2 kbps4.4 kbps2.0 kbps0.8 kbps
9.6 kbps4.8 kbps2.4 kbps1.2 kbps
CodeSymbol
28.8 ksps14.4 ksps 7.2 ksps 3.6 ksps
Long CodeMaskLong Code
Generator
PN Chips 1.2288 Mcps64-ary
OrthogonalModulator
ModulationSymbol(Walsh chip)
4.8 ksps(307.2 kcps)
Data BurstRandomizer
Frame Data Rate
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Reverse CDMA Channel Signal Generation
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Reverse Channel Modulator (Spreading)
• Identical I, Q signals; but different I, Q PN sequences (long code + short code)
• OQPSK modulation
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Reverse Link Modulation Parameters
• 20 ms interleaver for time diversity
• Orthogonal 64-ary Walsh modulation symbols
• Long code of period 2 42 -1 (for channel identification) concatenated with PN codes of length 2 15.
• Noncoherent OQPSK
• Diversity– time diversity: coding + interleaving
– path diversity: RAKE receiver
– spatial diversity: 2 Rx antennas (4 Rx antennas available during handoff)
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Reverse Channel Demodulation
• System with 4 fingers and 8 searchers
Antenna BAntenna A
Nocoherent Maximal Ratio Combining
Soft Decisions to Viterbi Decoder
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Signaling Flow of Registration Process
• MS notifies BS of its presence (location, status, identification, etc.) in the system
• IS-95 supports the following registration types:– power-up registration
– power-down registration
– timer-based registration
– distance-based registration
– zone-based registration
– parameter-change registration
– ordered registration
– implicit registration
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Signaling Flow of Registration Process
MS BS MSCNewVLR
OldVLR
HLR
Register Determination
Global Challenge
Register
Validate RAND
ISDN REGISTERREGISTER
IS-41 REGNOT
Database Update
IS-41 REGCANC
ConfirmREGNOT ResponseREGISTER ResponseISDN
REGISTERRegister Confirm
Chung-Wei KuATC/CCL/ITRI
Advanced Technology CenterComputer & Communications Research LaboratoriesIndustrial Technology Research Institute
Initialization and Call Processing of MS
• Acquires the pilot channel
• Receives the sync channel with sync channel message
• Adjust to system timing
• Receives the paging channel message
• Sends origination message (also registration) on the access channel
• Receives channel assignment message on the paging channel
• Initializes the traffic channel
• Enters conversion substate