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7/29/2019 3-CDMA-Channels STRUCTURE.ppt
1/60
Copyright 2003, ZTE CORPORATION
CDMA CHANNEL
STRUCTUREAND MODULATION
2004.10.3
7/29/2019 3-CDMA-Channels STRUCTURE.ppt
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Copyright 2003, ZTE CORPORATION
Upon completion of this lesson, the student will be able tomaster:
Objectives
-- The forward channel in IS-95
Pilot ;Sync ; Paging and Traffic
-- The reverse channel in IS-95Access; Traffic
-- CDMA Call Processing
-- New Channels in CDMA20001X
7/29/2019 3-CDMA-Channels STRUCTURE.ppt
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CDMA Forward Traffic
Channels
Used for the transmission of user and signalinginformation to a specific mobile station during a call.
Maximum number of traffic channels: 64 minus one
Pilot channel, one Sync channel, and 1 Paging channel. This leaves each CDMA frequency with at least 55 traffic
channels.
Unused paging channels can provide up to 6 additional channels.
Forward Traffic Channel
Forward Traffic Channel
Sync
Paging
Forward Traffic Channel
Forward Traffic Channel
Pilot
CDMA Cell Site
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Forward Traffic Channel
Generation
8 kb Vocoding
Walshfunction
PowerControl
Bit
I PN
9600bps4800 bps2400 bps1200 bps(Vocoder) Convolutional
EncodingandRepetition
1.2288McpsLong PN Code
Generation800Hz
R=1/2, K=9
Q PN
Decimator DecimatorUserAddress
Mask(ESN-based)
19.2ksps
1.2288Mcps
Scrambling
bits symbols chips
19.2ksps
CHANNEL ELEMENT
MUX
BlockInterleaving
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Rate 1/2, k=9 Convolutional
Encoding
Symbols generated as the information bits transit through the encoder, are relatedto all the bits currently in the register.
Each information bit contributes to multiple symbols.
Pattern of inter-relationships helps detect and correct errors.
The length of shift register is called constraint (K=9) length.
The longer the register, the better coding can correct bursty errors
Reduces power required to achieve same accuracy with coding
Here, two symbols are generated for every bit input (Rate 1/2).
CodeSymbolOutput
1 2 3 4 5 6 7 8
g0
g1
c0
c1
DataBitInput
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Symbols areWritten In
Symbols areRead Out
1 25 49 73 97 121 145 169 193 217 241 265 289 313 337 361
2 26 50 74 98 122 146 170 194 218 242 266 290 314 338 362
3 27 51 75 99 123 147 171 195 219 243 267 291 315 339 363
4 28 52 76 100 124 148 172 196 220 244 268 292 316 340 364
5 29 53 77 101 125 149 173 197 221 245 269 293 317 341 365
6 30 54 78 102 126 150 174 198 222 246 270 294 318 342 366
7 31 55 79 103 127 151 175 199 223 247 271 295 319 343 367
8 32 56 80 104 128 152 176 200 224 248 272 296 320 344 368
9 33 57 81 105 129 153 177 201 225 249 273 297 321 345 369
10 34 58 82 106 130 154 178 202 226 250 274 298 322 346 370
11 35 59 83 107 131 155 179 203 227 251 275 299 323 347 371
12 36 60 84 108 132 156 180 204 228 252 276 300 324 348 372
13 37 61 85 109 133 157 181 205 229 253 277 301 325 349 373
14 38 62 86 110 134 158 182 206 230 254 278 302 326 350 374
15 39 63 87 111 135 159 183 207 231 255 279 303 327 351 375
16 40 64 88 112 136 160 184 208 232 256 280 304 328 352 376
17 41 65 89 113 137 161 185 209 233 257 281 305 329 353 377
18 42 66 90 114 138 162 186 210 234 258 282 306 330 354 378
19 43 67 91 115 139 163 187 211 235 259 283 307 331 355 379
20 44 68 92 116 140 164 188 212 236 260 284 308 332 356 380
21 45 69 93 117 141 165 189 213 237 261 285 309 333 357 381
22 46 70 94 118 142 166 190 214 238 262 286 310 334 358 382
23 47 71 95 119 143 167 191 215 239 263 287 311 335 359 383
24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384
16 Columns
24Rows
Full Rate Block Interleave Array
The 384 modulation symbols in a frame are input into a 24 by 16 blockinterleave array read down by columns, from left to right
The modulation symbols are then read out of the array in rows
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Full Rate Block Interleave
Adjacent symbols are now separated in time This separation combats the effect of fast fading
A burst of errors could effect the area in red above and after the frame iswritten into the block de-interleave function at the mobile we see the
errors are spread out instead of being in consecutive order.
Symbols areWritten In
Symbols areRead Out
1 25 49 73 97 121 145 169 193 217 241 265 289 313 337 361
2 26 50 74 98 122 146 170 194 218 242 266 290 314 338 362
3 27 51 75 99 123 147 171 195 219 243 267 291 315 339 363
4 28 52 76 100 124 148 172 196 220 244 268 292 316 340 364
5 29 53 77 101 125 149 173 197 221 245 269 293 317 341 365
6 30 54 78 102 126 150 174 198 222 246 270 294 318 342 366
7 31 55 79 103 127 151 175 199 223 247 271 295 319 343 367
8 32 56 80 104 128 152 176 200 224 248 272 296 320 344 368
9 33 57 81 105 129 153 177 201 225 249 273 297 321 345 369
10 34 58 82 106 130 154 178 202 226 250 274 298 322 346 370
11 35 59 83 107 131 155 179 203 227 251 275 299 323 347 371
12 36 60 84 108 132 156 180 204 228 252 276 300 324 348 372
13 37 61 85 109 133 157 181 205 229 253 277 301 325 349 37314 38 62 86 110 134 158 182 206 230 254 278 302 326 350 374
15 39 63 87 111 135 159 183 207 231 255 279 303 327 351 375
16 40 64 88 112 136 160 184 208 232 256 280 304 328 352 376
17 41 65 89 113 137 161 185 209 233 257 281 305 329 353 377
18 42 66 90 114 138 162 186 210 234 258 282 306 330 354 378
19 43 67 91 115 139 163 187 211 235 259 283 307 331 355 379
20 44 68 92 116 140 164 188 212 236 260 284 308 332 356 380
21 45 69 93 117 141 165 189 213 237 261 285 309 333 357 381
22 46 70 94 118 142 166 190 214 238 262 286 310 334 358 382
23 47 71 95 119 143 167 191 215 239 263 287 311 335 359 383
24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384
16 Columns
24
Rows
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Data Scrambling
Every 64th PN chip is modulo-2 added to a symbol
Randomize transmitted data Effects of all 1s or 0s' traffic (impulse-like) is reduced
Eliminates probability of Pilot Reuse Error Mobile might demodulate a distant cell with same PN offset
BlockInterleaver
Long
Code PNGenerator
19.2 KspsModulationSymbols
User Address
Mask (ESN)Decimator
Divideby 64
19.2Ksps
1.2288Mcps
19.2Ksps
To PowerControl Mux
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Power Control Subchannel
Base station receiver estimates received signal strength of mobileover a 1.25 ms period (800/s)
A power control subchannel is transmitted continuously A power up/down command is sent 800 times a second
A puncturing technique sends Power Control Bits at full power anduncoded
19.2 Kspsfrom BlockInterleaver
1.2288 Mcps
User LongCode
Decimator
ScrambledModulationSymbol orPowerControl Bit19.2
Ksps
Decimator
Data ScramblingMUX
800 Hz Mux
Timing
Power ControlBit (800 bps)
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Orthogonal Spreading
Each symbol output from the Mux is exclusive ORd bythe assigned Walsh function
Walsh function has fixed chip rate of 1.2288 Mcps Result is 64 chips output for each symbol input
Channels are distinguished from each other by Walshfunction
Bandwidth used greatly exceeds source rate
To QuadratureSpreading19.2
Ksps
MUX
1.2288Mcps
Walsh Functionfrom Index
Wt800 Hz Mux
Timing
Power ControlBit (800 bps)
ScrambledData
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Quadrature Spreading
& Baseband Filtering
The forward traffic channel is combined with twodifferent PN sequences: I and Q
Baseband filtering ensures the waveforms are containedwithin the 1.25 MHz frequency range
The final step is to convert the two baseband signals toradio frequency (RF) in the 800 MHz or 1900 MHzrange
ConvolutionalEncoding
Code SymbolRepetition
VocoderProcessing
Baseband Trafficto RF Section
PCM Voice
BlockInterleaving
Data Scrambling
Power ControlSubchannel
OrthogonalSpreading
QuadratureSpreading
BasebandFiltering
(SymbolPuncturing)
WalshFunction
1.2288Mcps
19.2 kspsfrom PowerControl Mux
I-Channel Pilot PN Sequence1.2288 Mcps
BasebandFilter
Baseband
Filter
I
Q
I
Q
Q-Channel Pilot PN Sequence1.2288 Mcps
cos(2pfct)
sin(2pfct)
GAIN
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Composite I and Q
Each CHM hasa combiner andworks in a serialarray to
combine the Iand Q signalsfor all forwardchannels in a
partition sector
or cell.
Pilot
Channel
WalshCode
SyncChannel
WalshCode
Paging
Channel(s)
WalshCode
Forward Traffic
Channel(s)
WalshCode
IPN Code
QPN Code
CompositeI
CompositeQ
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Quadrature Phase Shift Key
(QPSK) Modulation
Q1 sin (2 fct) + Q2 sin (2 fct) = ( Q1 + Q2 ) sin (2 fct)
I1 cos (2 fct) + I2 cos (2 fct) = ( I1 + I2 ) cos (2 fct)
: XOR
S: Analog sum
: Baseband x Carrier
Every
Channel
Walshcode
Q PN Code
I PN Code
Basebandfilter
Basebandfilter
cos (2pfct)
sin (2pfc
t)
S
S
S
Gain
Control
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Forward Traffic Channel
Generation (13 kb Vocoding)
Walshfunction
PowerControl
Bit
I PN
14400bps7200 bps3600 bps1800 bps(Vocoder) Convolutional
EncodingandRepetition
1.2288Mcps
Long PN CodeGeneration 800Hz
R=1/2, K=9
Q PN
Decimator Decimator
UserAddress
Mask(ESN-based)
19.2ksps
1.2288
McpsScrambling
bits symbols chips
28.8ksps
CHANNEL ELEMENT
MUX
BlockInterleaving
SymbolPuncturing(13 kb only) 19.2
ksps
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Forward Channel Demodulation
Three elements must be capable of demodulating multipathcomponents
One must be a searcher that scans and estimates signal
strength at each pilot PN sequence offset
IS-95A/J-STD-008 requires a minimum of four processing elements thatcan be independently directed:
DigitalRake Receiver
ReceiverRF SectionIF, Detector
TransmitterRF Section
Vocoder
Traffic Correlator
PN xxx Walsh xx
Traffic Correlator
PN xxx Walsh xx
Traffic Correlator
PN xxx Walsh xx
Pilot SearcherPN xxx Walsh 0
ViterbiDecoder
CPUDuplexer
TransmitterDigital Section
Long Code Gen.
Open
Loop
Transmit Gain Adjust
Messages
Messages
Audio
Audio
Packets
Symbols
SymbolsChips
RF
RF
AGC
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Pilot Channel Used by the mobile station for initial system acquisition
Transmitted constantly by the base station
The same Short PN sequences are shared by all base stations
Each base station is differentiated by a phase offset
Provides tracking of:
Timing reference
Phase reference
Separation by phase provides for extremely high reusewithin one CDMA channel frequency
Acquisition by mobile stations is enhanced by:
Short duration of Pilot PN sequence
Uncoded nature of pilot signal Facilitates mobile station-assisted handoffs
Used to identify handoff candidates
Key factor in performing soft handoffs
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Pilot Channel Generation
The Walsh function zero spreading sequence is applied to the Pilot
The use of short PN sequence offsets allows for up to 512 distinct Pilots
per CDMA channel
The PN offset index value (0-511 inclusive) for a given pilot PN
sequence is multiplied by 64 to determine the actual offset Example: 15 (offset index) x 64 = 960 PN chips
Result: The start of the pilot PN sequence will be delayed
960 chips x 0.8138 microseconds per chip = 781.25 microsecond
PilotChannel(All 0s)
1.2288Mcps
I PN
Q PN
Walsh
Function 0
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Pilot Channel Acquisition
The mobile station starts generating the I and Q PN shortsequences by itself and correlating them with the received
composite signal at every possible offset. In less than 15 seconds (typically 2 to 4 seconds) all possibilities
(32,768) are checked.
The mobile station remembers the offsets for which it gets thebest correlation (where the Ec/Io is the best.
The mobile station locks on the best pilot (at the offset that resultsin the best Eb/N0), and identifies the pattern defining the start ofthe short sequences (a 1 that follows fifteen consecutive 0s).
Now the mobile station is ready to start de-correlating with aWalsh code.
0001 0001 0001 0001 0001 0001
Pilot Channel(Walsh Code 0)
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What is Ec/Io? Ec/Io
Measures the strength of the pilot Foretells the readability of the
associated traffic channels
Guides soft handoff decisions
Is digitally derived as the ratio of goodto total energy seen by the searchcorrelator at the desired PN offset
Never appears higher than Pilotspercentage of serving cells transmittedenergy
Can be degraded by strong RF fromother cells, sectors
Can be degraded by noise
Ec/Io dB
-25 -15 -10 0
Ec
Io
Energy ofdesired pilot alone
Total energy received
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Sync Channel
Used to provide essentialsystem parameters
Used during system acquisitionstage
Bit rate is 1200 bps
Sync channel has a frameduration of 26 2/3 ms
Frame duration matches theperiod of repetition of thePN Short Sequences
Simplifies the acquisition of
the Sync Channel once thePilot Channel has beenacquired
Mobile Station re-synchronizesat the end of every call
(Acquired Pilot)
Sync Channel
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Sync Channel Generation
1200 bps
Walsh Function 32
1.2288 Mcps
IPN
ConvolutionalEncoderand
RepetitionBlock
Interleaver
R=1/2 K=9
ModulationSymbols
4800 sps 4800 sps
Bits Chips
QPN
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Sync Channel Message
Body Format
MSG_TYPE (00000001)
P_REV
MIN_PREV
SID
NID
PILOT_PN
LC_STATE
SYS_TIME
LP_SECLTM_OFF
DAYLT
PRAT
CDMA_FREQ
8
8
8
15
16
9
42
36
86
1
2
11
FieldLength(bits)
Total : 170
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Sync Message Parameters Message Type (MSG_TYPE) Identifies this message and
determines its structure (set to the fixed value of00000001)
Protocol Revision Level (P_REV) Shall be set to 00000001
Minimum Protocol Revision Level (MIN_P_REV) 8-bit unsignedinteger identifying the minimum protocol revision level required tooperate on the system. Only mobile stations that support revisionnumbers greater than or equal to this field can access the system.
System ID (SID) 16-bit unsigned integer identifying the system
Network ID (NID) 16-bit unsigned integer identifying the networkwithin the system (defined by the owner of the SID)
Pilot PN Sequence Offset Index (PILOT_PN) Set to the pilot PNoffset for the base station (in units of 64 chips), assigned by thenetwork planner
Long Code State (LC_STATE) Provides the mobile station with thebase station long code state at the time given by the SYS_TIME field,generated dynamically
System Time (SYS_TIME) GPS system-wide time as 320 ms afterthe end of the last superframe containing any part of this message,minus the pilot PN offset, in units of 80 ms, generated dynamically
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Sync Channel Message
Parameters (cont.)
Leap Seconds (LP_SEC) Number of leap seconds that have occurredsince the start of system time (January 6, 1980 at 00:00:00 hours) asgiven in the SYS_TIME field, generated dynamically
Local Time Offset (LTM_OFF) Twos complement offset of localtime from system time in units of 30 minutes, generated dynamically
Current local = SYS_TIME LP_SEC + LTM_OFF
Daylight savings time indicator(DAYLT) Determined by thenetwork planner
1 if daylight savings in effect in this base station
0 otherwise
Paging Channel Data Rate (PRAT) The data rate of the pagingchannel for this system, determined by the network planner
00 if 9600 bps
01 if 4800 bps
CDMA Frequency Assignment (CDMA_FREQ)
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Paging Channels
There is one paging channel per sector per CDMAcarrier
The Paging Channel uses Walsh function 1
Two rates are supported: 9600 and 4800 bps
Paging Channel
Used by the base station totransmit system overhead informationand mobile station-specific messages.
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Paging Channel Generation
Walsh code #1 is used to spread the data. This results in an increase to 1.2288Mcps
That is, 24,576 9600 [4800] bps x 0.020 s = 192 [96] bits in a PagingChannel frame.
The Rate 1/2 convolutional encoder doubles the bit rate, resulting 384 [192]
code symbols in a Paging Channel frame.
If the 4800 bps rate is used, the repetition process doubles the rate again, so that,at either rate, 384 modulation symbols per Paging Channel frame result
384 modulation symbols per frame times 50 frames per second = 19.2 Ksps
chips per Paging Channel frame, or 128 [256] chips per original bit at 9600[4800] bps
9600 bps
4800 bps
Walshfunction
1.2288Mcps
Q PN
1.2288Mcps
19.2Ksps
19.2KspsPaging Channel
Address Mask
R = 1/2 K=9
Decimator
ConvolutionalEncoder &Repetition
I PN
BlockInterleaving
Scrambling
Long PN CodeGenerator
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Paging Channel Time Slot Structure
7
6
5
4
3
2
1
0
SCI 163.84 s
T 2SCI
SCI = Slot Cycle IndexT = Slot Cycle Length in 1.28 sunits 80 ms
1.28 s
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MS How to Watch Paging Channel
System Time
Paging Channel Slots
2047 0 1 2 3 4 12 13 14 15 16 17
1.28 seconds
Mobile Stationin Non-Active State
Assigned PagingChannel Slot
Re-acquisition ofCDMA System
Mobile Stationin Non-Active State
80 ms
Paging Channel O erhead
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Paging Channel Overhead
Messages
Mobile-Station-DirectedMessages
OverheadMessages
Access Parameters Message
System Parameters Message
CDMA Channel List Message
Extended System Parameters Message
Extended Neighbor List Message
ConfigurationParameterMessages
Global Service Redirection Message
PagingMessages
ACC_MSG_SEQ
CONFIG_MSG_SEQ
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CDMA Reverse Traffic
Channels
Used when a call is in progress to send: Voice traffic from the subscriber
Response to commands/queries from the base station
Requests to the base station
Supports variable data rate operation for:
8 Kbps vocoder Rate Set 1 - 9600, 4800, 2400 and 1200 bps
13 Kbps vocoder
Rate Set 2 - 14400, 7200, 3600, 1800 bps
Reverse Traffic Channel
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9600 bps4800 bps
2400 bps1200 bps
28.8ksps
R=1/3,K=9
1.2288McpsUser Address
Mask
LongPN Code
Generator
28.8ksps OrthogonalModulation
Data BurstRandomizer
307.2kcps
1.2288
Mcps
Q PN(no offset)
I PN(no offset)
D
1/2 PNChipDelay
DirectSequenceSpreading
ConvolutionalEncoder &Repetition
BlockInterleaver
Reverse Traffic Channel
Generation at 8 kb Vocoding
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+
+
+
g0
g1
g2
Information bits(INPUT)
Code Symbols(OUTPUT)
Code Symbols(OUTPUT)
Code Symbols(OUTPUT)
1 2 3 4 5 6 7 8
Rate 1/3 Convolutional
Encoder
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28.8 kspsFrom Coding& SymbolRepetition
28.8 ksps toOrthogonalModulation
Input Array(Normal
Sequence)32 x 18
Output Array(ReorderedSequence)
32 x 18
Reverse Traffic Channel
Block Interleaving
20 ms symbol blocks are sequentially reordered
Combats the effects of fast fading
Separates repeated symbols at 4800 bps and below
Improves survivability of symbol data
Spreads the effect of spurious interference
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Reverse Traffic Channel:
64-ary Orthogonal Modulation
For every six symbols in, 64 Walsh Chips are output
Six symbols are converted to a decimal number from 0-63
The Walsh code that corresponds to the decimal number becomes theoutput
1 0 1 1 0 0 1 0 0 0 1 1
Symbols
3544 Walsh Lookup TableWalshChipwithina WalshFunction
01234567
11
8901
1111
2345
1111
6789
2222
0123
2222
4567
2233
8901
3333
2345
3333
6789
4444
0123
4444
4567
4455
8901
5555
2345
5555
6789
6666
0123
0
1
2
3
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
4
5
6
7
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
8
9
10
11
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
12
13
14
15
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
Wals
16
17
18
19
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
h
Fu
20
21
22
23
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
ncti
24
25
26
27
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
onI
2829
30
31
00000101
0011
0110
11111010
1100
1001
11111010
1100
1001
00000101
0011
0110
11111010
1100
1001
00000101
0011
0110
00000101
0011
0110
11111010
1100
1001
00000101
0011
0110
11111010
1100
1001
11111010
1100
1001
00000101
0011
0110
11111010
1100
1001
00000101
0011
0110
00000101
0011
0110
11111010
1100
1001
ndex
32
33
34
35
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
36
37
38
39
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
40
41
42
43
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
44
45
46
47
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
48
49
50
51
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
52
53
54
55
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
56
57
58
59
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
60
61
62
63
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1 0 0 0 1 . . . 1 1 0 1 0
64 Chip Pattern ofWalsh Code # 35
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Reverse Traffic Channel:
Direct Sequence Spreading
Output of the randomizer is direct sequence spread by the
long code The mobile station can use one of two unique long code
masks:
A public long code mask based on the ESN
A private long code mask
1.2288Mcps
User AddressMask
LongCode PN
Generator
Data BurstRandomizer
307.2kcps To Quadrature
Spreading
1.2288Mcps
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Offset Quadrature Spreading &
Baseband Filtering
The channel is spread by a pilot PN sequence with a zerooffset
Baseband filtering ensures that the waveform is containedwithin the required frequency limits
Baseband signals converted to radio frequency (RF) inthe 800 MHz or 1900 MHz range
1.2288Mcps
I-Channel Pilot PN Sequence1.2288 Mcps
PN
I
Q
I
Q
cos(
2
pfct)
sin(2 fct)PN chip
1.2288 Mcps
FromData BurstRandomizer
RF Converters
D
1/2 PN ChipTime Delay
BasebandFilter
BasebandFilter
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14400 bps7200 bps
3600 bps1800 bps
28.8
ksps
R=1/2,K=9
1.2288McpsUser Address
Mask
LongPN Code
Generator
28.8
ksps OrthogonalModulation
Data BurstRandomizer
307.2
kcps
1.2288Mcps
Q PN(no offset)
I PN(no offset)
D
1/2 PNChipDelay
Direct
SequenceSpreading
ConvolutionalEncoder &Repetition
BlockInterleaver
Reverse Traffic Channel
Generation at 13 kb Vocoding
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Reverse Channel Demodulation
IS-95A/J-STD-008 requires a process that is complementary to the mobilestation modulation process
CDMA processing benefits from multipath components
Signals from several receive elements can be combined to improvereceive signal quality
U/DCommand
De-InterleaverSpeechOutput
C
ombiner
BTS Receiver BSC
Power ControlDecision
ViterbiDecoder
Vocoder
Demodulator SearchCorrelator
Demodulator SearchCorrelator
Demodulator
Search
Correlator
Demodulator SearchCorrelator
PN+ tUser Long Code
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Access Channels
Used by the mobile station to: Initiate communication with the base station
Respond to Paging Channel messages
Has a fixed data rate of 4800 bps
Each Access Channel is associated with only one Paging
Channel Up to 32 access channels (0-31) are supported per Paging
Channel
4800 bps
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28.8kspsConvolutional
Encoder &Repetition
R = 1/3
1.2288Mcps
Access ChannelLong Code Mask
Long PN CodeGenerator
28.8ksps Orthogonal
Modulation
307.2kcps
1.2288Mcps
Q PN (No Offset)
I PN (No Offset)
D
1/2 PNChipDelay
BlockInterleaver
Access ChannelInformation
(88 bits/Frame)
4.8 kpbs
DirectSequenceSpreading
Access Channel Generation
Message attempts are randomized to reduce probability ofcollision
Two message types:
A response message (in response to a base stationmessage)
A request message (sent autonomously by the mobile
station)
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Access Channel Long Code MaskAn Access Channel is scrambled by the longcode, offset by a mask constructed as follows:
Where:
ACN is the Access Channel Number,
PCN is the Number of the associated Paging ChannelBASE_ID is the base station identification number, and
PILOT_PN is the Pilot short PN code offset index
1 1 0 0 0 1 1 1 1 PCNACN BASE_ID PILOT_PN
41 33 32 028 27 25 24 9 8
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Access Channel Probing
AccessProbe 1
Access
Probe 1
Access
Probe 1
Access
Probe 1
Access Probe
1 + NUM_STEP
(16 max)
System
Time
TA RT TA RT TA RT TA
PI
PI
PI
IP(InitialPower)
See previous
figure
ACCESS
PROBE
SEQUENCE
Select Access Channel (RA)
initialize transmit power
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Access Channel Probing
System
Time
See previousfigure
ONE ACCESS CHANNEL SLOT
ACH Frame(20 ms)
ACCESS CHANNELPREAMBLE
(Modulation Symbol 0)
ACCESS CHANNELMESSAGE CAPSULE
ACTUAL ACCESS PROBE TRANSMISSION
PN Randomization Delay = RN chips = RN x 0.8138 s
ACCESSPROBE
1 + PAM_SZ(1 - 16 frames)
3 + MAX_CAP_SZ(3 - 10 frames)
4 + PAM_SZ + MAX_CAP_SZ(4 - 26 frames)
Access ChannelSlot and Frame
Boundary
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Access Channel Probing
Seq 2 Seq 3
Seq MAX_REQ_SEQ(15 max)
RSRS
Access Attempt
PD
System
Time
Access ProbeSequence 1
REQUEST
ATTEMPT
Request messageready for transmission
PD PD
Seq 2 Seq 4Seq 3Seq MAX_RSP_SEQ
(15 max)
RSRS
Access Attempt
RS
System
Time
Access ProbeSequence 1
RESPONSEATTEMPT
Response messageready for transmission
Access Channel Probing
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Access Channel Probing
Parameters RA - Access Channel Number. Random value between 0 and ACC_CHAN; generated before
every sequence (maximum range is 0 - 31).
IPInitial Open-Loop Power. Calculated in dBm as follows:
IP = k - Mean Input Power (dBm) + NOM_PWR (dB)
- NOM_PWR_EXT x 16 (dB) + INIT_PWR (dB)
where k = -73 for 800 MHz Cellular and -76 for 1900 PCS.
PIPower Increment. Equal to PWR_STEP in dB (range is 0 to 7 dB). TAAcknowledgment Response Timeout (timeout from the end of the slot). Calculated in ms
as follows (range is 160 to 1360 ms):
TA = 80 x (2 + ACC_TMO)
RTProbe Backoff. Random value between 0 and 1 + PROBE_BKOFF; generated before
every sequence (maximum range is 0 - 16 slots).
RSSequence backoff. Random value between 0 and 1 + BKOFF; generated before everysequence (except the first sequence). Maximum range of values is 0 to 16 slots
PDPersistence delay. (Value used to implement the persistence test).
RNPN Randomization Delay. (0 to 511 chips) . Generated before every sequence, between
0 and 2 PROBE_PN_RAN - 1, by hash, using ESN_S.
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CDMA MS Call ProcessingPower-Up
Initialization
Idle
SystemAccess
Traffic
Mobile stationhas fully acquired
system timing
Mobile station receives a PagingChannel message requiring ACK
or response, originates a call, orperforms registration
Mobile station is directedto a Traffic Channel
Mobile station ends useof the Traffic Channel
Mobile station receives an ACK toan Access Channel transmission
other than an Origination Messageor a Page Response Message
Mobile station is in idle handoffwith NGHBR_CONFG equal to
011 or is unable to receivePaging Channel Message
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Mobile Station Originated Call
Allocatesresources
Mobile Station Base Station
Detects user-initiated call
Sends Origination Message
ACCESS
(FW null traffic is arriving but themobile station does not know onwhat channel; therefore, the mobile
station cannot start decoding it)
Sends message with thisinformation to the switch
Sends Base Station Acknowledge-ment Order
FW TRAFFIC
Allocates resources for ServiceOption 1
Begins transmitting null ReverseTraffic Channel Data
Sends Service Request Messagefor Service Option 1 RV TRAFFIC
Acquires the Reverse TrafficChannel
Sends Base Station Acknowledge-ment Order
FW TRAFFIC
Sets up Traffic Channel
Receives N5m=2 consecutive validframes
Begins sending the Reverse TrafficChannel Preamble
Sends Channel AssignmentMessage
PAGING
RV TRAFFIC
Switch
Sets up Traffic Channel
Begins sending null traffic
Stops probingPAGING
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Mobile Station Originated Call
(User Conversation)
Optional
Applies ring back from audio path
Optional
Removes ring back from audio path
Begins processing primary traffic inaccordance with Service Option 1
Sends Service ConnectCompletion Message
Optional
Sends Origination ContinuationMessage
RV TRAFFIC
RV TRAFFIC
Optional
Sends Alert With InformationMessage (ring back tone)
Optional
Sends Alert With InformationMessage (tones off)
Message sent to the switchindicating that the mobile stationis ready
FW TRAFFIC
FW TRAFFIC
Completesthe call
(User Conversation)
Allocates resources for ServiceOption 1
Sends Service Connect Message
Mobile Station Base Station Switch
FW TRAFFIC
M bil S i T i d C ll
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Mobile Station Terminated Call
Stops probing
(FW null traffic is arriving but themobile station does not know onwhat channel; therefore, the mobilestation cannot start decoding it)
Sets up Traffic Channel
Begins sending null TrafficChannel data
Acquires the Reverse TrafficChannel
Sends Base Station Acknowledge-ment Order
Sets up Traffic Channel
Receives N5m=2 consecutivevalid frames
Begins sending the ReverseTraffic Channel Preamble
Begins transmitting null TrafficChannel data
Sends General Page Message
Sends Page Response Message ACCESS
PAGING
RV TRAFFIC
FW TRAFFIC
PAGING
FW TRAFFIC
RV TRAFFIC
Switch
Mobile Station Base Station
Sends Channel AssignmentMessage
Sends Base Station Acknowledge-ment Order
Sends message to switchindicating that the mobile stationhas responded
Allocates
resources
PAGING
Switch
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Mobile Station Terminated Call
Sends Alert With InformationMessage (ring)
Begins processing primary traffic inaccordance with Service Option 1
Sends Service ConnectCompletion Message
Starts ringing
User answers call
Stops ringing
Sends Connect Order
(User Conversation) (User Conversation)
FW TRAFFIC
RV TRAFFIC
RV TRAFFIC
Sends Service Connect MessageFW TRAFFIC
Sends message to the switchindicating that the mobilestation is ready
Call proceeds
Allocates resources for ServiceOption 1
Sends Service Response Messageaccepting Service Option 1
RV TRAFFIC
Sends Service Request Msgfor Service Option 1
FW TRAFFIC
Begins transmitting null TrafficChannel data RV TRAFFIC
SwitchMobile Station Base Station
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CDMA20001XRtt
New Channel Structure
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Benefits of the CDMA2000
1x Standards
Increased mobile standby battery life (via Quick Paging
Channel)
Total backward compatibility to reuse switch and call
processing features
2-3 dB better coverage
High speed 153.6 kbps packet data capabilities
CDMA2000 1x = 1.25 MHz Radio Transmission Technology
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Backward Compatible with
IS-95 Air Interface
No need to change any RF infrastructure
Capacity improvements will not be realized until most IS-95 subscribers disappear
IS-95 mobiles are supported in the IS-2000 standardfor 1xRTT:
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Cdma2000 1xRtt Channel(Qualcomm)
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Channel List: 1xRTT vs. IS-95 IS-95B built on the IS-95A channels, and introduced two new channels
Fundamental channel was the same as IS-9A traffic channel
Supplemental code channels assigned to support rates above14.4Kbps
IS-2000 1xRTT continue to build on the IS-95 channels
IS-95 channels continue to be supported in IS-2000 to support IS-95 mobiles
Pilot channelSync channelPaging channel Access channelForward Traffic Channel Reverse Traffic Channel
Fundamental channel Fundamental channelSupplemental Code channel (F-SCCH) Supplemental Code channel (R-SCCH)
Supplemental channel (F-SCH) Supplemental channel (R-SCH)Quick Paging channel (F-QPCH) Reverse Pilot channel (R-PICH)
IS-95B
1xRTT
IS-95A
Forward Reverse
F d S l t l
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Forward Supplemental
Channel (F-SCH) Assigned for high-speed packet data (>9.6 kbps) in the forward
direction; (FCH is always assigned to each call)
Up to 2 F-SCH can be assigned to a single mobile
SCH cannot exist without having a fundamental channelestablished
F-SCH supports Walsh code lengths of 4 - 1024 depending on data rateand chip rate
SCH-1 File transfer at 144 kbps
FCH Voice, power control and link continuity
Mobile 1
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Reverse Supplemental
Channel (R-SCH) Used for high-speed packet data (>9.6 kbps)
Difference between F-SCH and R-SCH is in Walsh code basedspreading
F-SCH supports Walsh code lengths of 4 to 128 (1xRTT) or 1024
(3xRTT) depending on data rate and chip rate R-SCH uses either a 2-digit or 4-digit Walsh code; rate matching
done by repetition of encoded and interleaved symbols
Walsh code allocation sequence is pre-determined andcommon to all mobiles
Users are differentiated using long PN code with user mask
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Reverse Pilot Channel
(R-PICH)
Mobile transmits well-known pattern (pilot)
Allows base station to do timing corrections withouthaving to guess where mobile is (in search window)
Mobile can transmit at lower power, reducing interference
to others
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Quick Paging Channel
(F-QPCH) More efficient monitoring of paging channel by mobile, enhancement
to slotted paging
Mobile monitors QPCH to determine if there is a page forthcoming on
paging channel in its slot (looks at 1-bit paging indicator)
If no flag, then mobile goes back to sleep; if flag, then mobile monitors
appropriate slot and decodes general page message
Without QPCH, mobile must monitor regular paging channel slot and
decode several fields to determine whether page is for it or not; this
drains mobile batteries quickly
The main purpose of QPCH is to save mobile battery life.
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The End!
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