cdma m1 overview[1]
TRANSCRIPT
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 1
Fundamentals of CDMA
Alexander Sierra
Lesson 1 - Overview
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 2
Basics
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 3
Why CDMA?
Is the technology of choice for both 800 MHz Cellular and 1900 MHz PCS service providers
Satisfies CTIA Users’ Performance Requirements
Provides high capacity (many times the capacity of AMPS)
Provides privacy through its coding scheme
CDMA
CDMA
ode
ivision
ultiple
ccess
CDMA is extremely robust and provides excellent audio quality
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 4
What is Multiple Access?
Since the beginning of telephony and radio, system operators have tried to squeeze the maximum amount of traffic over each circuit
Types of Media -- Examples:· Twisted pair - copper· Coaxial cable· Fiber optic cable· Air interface (radio signals)
Advantages of Multiple Access· Increased capacity: serve more users· Reduced capital requirements since fewer
media can carry the traffic· Decreased per-user expense· Easier to manage and administer
Transmission
Medium
Each pair of users enjoys a dedicated,
private circuit through the transmission
medium, unaware that the other users exist.
Multiple Access: Simultaneous private use of a transmission medium by multiple, independent users.
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 5
Multiple Access Technologies
The physical transmission medium is a resource that can be subdivided into individual channels according to different criteria depending on the technology used:
Here’s how the three most popular technologies establish channels:· FDMA Frequency Division Multiple Access
- each user on a different frequency- a channel is a frequency
· TDMA Time Division Multiple Access- each user on a different window period in time
(“time slot”)- a channel is a specific time slot on a specific
frequency· CDMA Code Division Multiple Access
- each user uses the same frequency all the time, but mixed with different distinguishing code patterns
- a channel is a unique (set of) code pattern(s)Frequency
Time
Power
FrequencyTime
Power
FrequencyTime
Power
FDMA
TDMA
CDMA
Channel: An individually-assigned, dedicated pathway through a transmission medium for one user’s information
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 6
Defining Our Terms
CDMA Channel or CDMA Carrier or CDMA Frequency· Duplex channel made of two 1.25 MHz-wide bands of electromagnetic
spectrum, one for Base Station to Mobile Station communication (called the FORWARD LINK or the DOWNLINK) and another for Mobile Station to Base Station communication (called the REVERSE LINK or the UPLINK)
· in 800 Cellular these two simplex 1.25 MHz bands are 45 MHz apart· in 1900 MHz PCS they are 80 MHz apart
CDMA Forward Channel· the 1.25 MHz Forward Link
CDMA Reverse Channel· the 1.25 MHz Reverse Link
CDMA Code Channel· each individual stream of 0’s and 1’s contained in either the CDMA Forward
Channel or in the CDMA Reverse Channel· Code Channels are characterized (made unique) by mathematical codes· code channels in the forward link: Pilot, Sync, Paging and Forward Traffic
channels· code channels in the reverse link: Access and Reverse Traffic channels
45 or 80 MHz
CDMA CHANNELCDMA
ReverseChannel 1.25 MHz
CDMAForwardChannel 1.25 MHz
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 7
Other Technologies: Avoiding Interference
In conventional radio technologies, the desired signal must be strong enough to override any interference
AMPS, TDMA and GSM depend on physical distance separation to keep interference at low levels
Co-channel users are kept at a safe distance by careful frequency planning
Nearby users and cells must use different frequencies to avoid interference
2
3
4
5 6
7
4
6
4
7 2
7
2
5
3
5
36
1
1
1
1
1
1
1
AMPS-TDMA-GSM
Figure of Merit: C/I(carrier/interference ratio)
AMPS: +17 dBTDMA: +14 to 17 dBGSM: +12 to 14 dB
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 8
CDMA: Using a New Dimension
All CDMA users occupy the same frequency at the same time! Frequency and time are not used as discriminators
CDMA operates by using CODES to discriminate between users
CDMA interference comes mainly from nearby users
Each user is a small voice in a roaring crowd -- but with a uniquely recoverable code
Transmit power on all users must be tightly controlled so their signals reach the base station at the same signal level
Figure of Merit: Ec/Io, Eb/No
(energy per chip [bit] /interference [noise] spectral density)
CDMA: Ec/Io -17 to -2 dBCDMA: Eb/No ~+6 dB
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 9
CDMA Is a Spread-Spectrum System
Traditional technologies try to squeeze the signal into the minimum required bandwidth
Direct-Sequence Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signal · The spreading sequence is
independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original data
The de-spreading gives substantial gain proportional to the bandwidth of the spreading signal
CDMA uses a larger bandwidth but then uses resulting processing gain to increase capacity
Spread Spectrum Payoff:Processing Gain
Spread SpectrumTRADITIONAL COMMUNICATIONS SYSTEM
SlowInformation
Sent
TX
SlowInformationRecovered
RX
NarrowbandSignal
SPREAD-SPECTRUM SYSTEM
FastSpreadingSequence
SlowInformation
Sent
TX
SlowInformationRecovered
RX
FastSpreadingSequence
Wideband Signal
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 10
Spread Spectrum Principles
1.25 MHz30 KHz
Power is “Spread” Over a Larger Bandwidth
MATHHAMMER
MATHHAMMER
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 11
Spread Spectrum Principles
Many code channels are individually“spread” and then added together tocreate a “composite signal”
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 12
Spread Spectrum Principles
UNWANTED POWERFROM OTHER SOURCES
Using the “right” mathematicalsequences any Code Channelcan be extracted from the receivedcomposite signal
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 13
Anything We Can Do, We Can Undo
Any data bit stream can be combined with a spreading sequence The resulting signal can be de-spread and the data stream
recovered if the original spreading sequence is available and properly synchronized
After de-spreading, the original data stream is recovered intact Note - The spread sequences actually shown are icons, not accurate or to scale
ORIGINATING SITE DESTINATION
SpreadingSequence
SpreadingSequence
InputData
(Base Band)
RecoveredData
(Base Band)
Spread Data Stream(Base Band + Spreading Sequence)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 14
“Shipping and Receiving” via CDMA
Whether in shipping and receiving, or in CDMA, packaging is extremely important!
Cargo is placed inside “nested” containers for protection and to allow addressing
The shipper packs in a certain order, and the receiver unpacks in the reverse order
CDMA “containers” are spreading codes
Fed
Ex
Data Mailer
Fed
Ex
DataMailer
Shipping Receiving
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 15
CDMA’s Nested Spreading Sequences
CDMA combines three different spreading sequences to create unique, robust channels
The sequences are easy to generate on both sending and receiving ends of each link
The sequences are applied in succession at the sending end and then reapplied in opposite order to recover the original data stream at the receiving end
SpreadingSequence
A
SpreadingSequence
B
SpreadingSequence
C
SpreadingSequence
C
SpreadingSequence
B
SpreadingSequence
A
InputData
X
RecoveredData
X
X+A X+A+B X+A+B+C X+A+B X+ASpread-Spectrum Chip Streams
ORIGINATING SITE DESTINATION
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 16
How Many Spreading Codes Do We Need?(Discriminating Among Forward Code Channels)
A Mobile Station, tuned to a particular CDMA frequency, receives a Forward CDMA Channel from a sector in a Base Station.
This Forward CDMA Channel carries a composite signal made of up to 64 “forward code channels”
Some of these code channels are “traffic channels” while other are “overhead channels” needed by the CDMA system to operate properly.
A set of 64 mathematical codes is needed to differentiate the 64 possible forward code channels that can be contained in a Forward CDMA Channel.· The codes in this set are called “Walsh Codes”
SyncPilot
FW Traffic(for user #1)
Paging
FW Traffic(for user #2)
FW Traffic(for user #3)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 17
How Many Spreading Codes Do We Need?(Discriminating Among Base Stations)
A mobile Station is surrounded by Base Stations, all of them transmitting on the same CDMA Frequency
Each Sector in each Base Station is transmitting a CDMA Forward Traffic Channel containing up to 64 distinct forward code channels
A Mobile Station must be able to discriminate between different Sectors of different Base Stations and listen to only one set of code channels
Two binary digit sequences called the I and Q Short PN Sequences (or Short PN Codes) are defined for the purpose of identifying sectors of different base stations
These Short PN Sequences can be used in 512 different ways in a CDMA system. Each one of them constitutes a mathematical code which can be used to identify a particular sector of a particular base station
A B
Up to 64Code Channels
Up to 64Code Channels
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 18
How Many Spreading Codes Do We Need?(Discriminating Among Reverse Code Channels)
The CDMA system must be able to uniquely identify each Mobile Station that may attempt to communicate with a Base Station
A very large number of Mobile Stations will be in the market
One binary digit sequence called the Long PN Sequence (or Long PN Code) is defined for the purpose of uniquely identifying each possible reverse code channel
This sequence is extremely long and can be used in trillions of different ways. Each one of them constitutes a mathematical code which can be used to identify a particular user (and is then called a User Long Code) or a particular “access channel” (explained later in this course)
RV Trafficfrom M.S.
#1837732008RV Trafficfrom M.S.
#8764349209
RV Trafficfrom M.S.
#223663748
System AccessAttempt by M.S.#4348769902
(on access channel #1)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 19
Putting it All Together: CDMA Channels
The three spreading codes are used in different ways to create the forward and reverse links
A forward channel exists by having a specific Walsh Code assigned to the user, and a specific PN offset for the sector
A reverse channel exists because the mobile uses a specific offset of the Long PN sequence
BTS
WALSH CODE: Individual UserSHORT PN OFFSET: Sector
LONG CODE OFFSET: individual handset
FORWARD CHANNELS
REVERSE CHANNELS
LONG CODE:Data
Scrambling
WALSH CODES:used as symbols
for robustness
SHORT PN:used at 0 offset
for tracking
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 20
Pilot Walsh 0
Walsh 19
Paging Walsh 1
Walsh 6
Walsh 11
Walsh 20
Sync Walsh 32
Walsh 42
Walsh 37
Walsh 41
Walsh 56
Walsh 60
Walsh 55
Code Channels in the Forward Direction
PILOT: WALSH CODE 0· The Pilot is a “structural beacon” which
does not contain a character stream. It is a timing source used in system acquisition and as a measurement device during handoffs
SYNC: WALSH CODE 32· This carries a data stream of system
identification and parameter information used by mobiles during system acquisition
PAGING: WALSH CODES 1 up to 7· There can be from one to seven paging
channels as determined by capacity needs. They carry pages, system parameters information, and call setup orders
TRAFFIC: any remaining WALSH codes· The traffic channels are assigned to
individual users to carry call traffic. All remaining Walsh codes are available, subject to overall capacity limited by noise
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 21
BTS (1 sector)MTX BSC
FECWalsh #1
Sync FECWalsh #32
Walsh #0
FECWalsh #12
FECWalsh #23
FECWalsh #27
FECWalsh #44
Pilot
Paging
Vocoder
Vocoder
Vocoder
Vocoder
more moremore
Trans-mitter,
Sector X
S
I Q
Short PN CodePN Offset 246
Coding Process in the Forward Direction
A Forward Channel is identified by:
its CDMA RF carrier Frequency
the unique Short Code PN Offset of the sector
the unique Walsh Code of the user
CDMAFrequency
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 22
REG
1-800242
4444
BTS
Code Channels in the Reverse Direction
There are two types of CDMA Reverse Channels:
TRAFFIC CHANNELS are used by individualusers during their actual calls to transmit trafficto the BTS· a reverse traffic channel is defined by a user-specific
public or private Long Code mask· there are as many reverse Traffic Channels as
there are CDMA phones in the world
ACCESS CHANNELS are used by mobile stations not yet in a call to transmit registration requests, call setup requests, page responses, order responses, and other signaling information· an access channel is defined by a user-independent
public long code mask· Access channels are paired with Paging Channels.
There can be up to 32 access channels per paging channel
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 23
MTX BSC BTS (1 sector)
Channel Element
Access Channels
Vocoder
Vocoder
Vocoder
Vocoder
more more
Receiver,Sector X
Channel Element
Channel Element
Channel Element
Channel Element
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
more
UserLongCode User
LongCode User
LongCode
UserLongCode
UserLongCode
UserLongCode
Coding Process in the Reverse Direction
A Reverse Channel is identified by: its CDMA RF carrier Frequency the unique Long Code PN Offset
of the individual handset
CDMAFrequency
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 24
Details of Operation
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 25
Variable Rate Vocoding & Multiplexing(Traffic Channels Only)
Vocoders compress speech, reduce bit rate
CDMA uses a superior Variable Rate Vocoder· full rate during speech· low rates in speech pauses· increased capacity· more natural sound
Voice, signaling, and user secondary data may be mixed in CDMA frames
DSP QCELP VOCODER
Codebook
PitchFilter
FormantFilter
Coded Result Feed-back
20ms Sample
Rate Set 2 Frame Sizesbits
Full Rate Frame
1/2 Rate Frame
1/4 Rt.
1/836
72
144
288
Frame Contents: can be a mixture ofVoice Signaling Secondary
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 26
Converting Bits into Symbols
The bits in a 20 ms traffic frame may include one or more of the following· voice information (from the vocoder)· signaling information· secondary traffic information
When Forward Error Correction algorithms are applied to these information bits, the resulting 0s and 1s are called symbols· bits and symbols are related in a complex
many-to-many fashion- the information in one bit is distributed among
many symbols, and one symbol carries some of the information of many bits
· all forward traffic frames contain 384 symbols· all reverse traffic frames contain 576 symbols
Bits
Symbols
Forward ErrorCorrection
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 27
Spreading Symbols into Chips
Symbols are converted into special 64-chip patterns for transmission· there are 64 such patterns called “Walsh
codes”· in the forward link, just one of these patterns is
assigned to each user’s stream of symbols (code channel)
- each ‘0’ symbol is replaced by the selected pattern (Walsh code)
- each ‘1’ symbol is replaced by the logical negation of the selected pattern
· in the reverse link, all the 64 patterns (but not their logical negations) are used in every code channel
- each group of six symbols is interpreted as a binary value in the 0-63 range and replaced by the corresponding Walsh code
Symbols
Chips
Coding andSpreading
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 28
Reverting The Process To revert the process, first the symbols are
recovered as follows· in the forward direction, the mobile station correlates
the received signal with the selected Walsh code pattern (integrating the power over 64 chips); a perfect match corresponds to a ‘0’ symbol; a perfect no-match corresponds to a ‘1’ symbol; for anything between these extremes, the mobile station guesses based on which case the partial match resembles closer
· in the reverse direction, the BTS matches the received signal with each possible Walsh code and selects the pattern that produces the highest degree of correlation as the representation of the last group of six symbols sent
When all the symbols for a 20 millisecond frame have been recovered, the Viterbi decoder is used to guess the block of bits (frame) that most probably corresponds to this block of symbols
Then, the CRC of this frame is calculated to determine if the guess was successful; if not, the frame is discarded (or “erased”)
Symbols
Chips
Despreading(integraton)
Bits
ViterbiDecoder
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 29
Spectrum Usage and System Capacity:Signal Bandwidth, Vulnerability and Frequency Reuse
Each wireless technology (AMPS, NAMPS, D-AMPS, GSM, CDMA) uses a specific modulation type with its own unique signal characteristics
The total traffic capacity of a wireless system is determined largely by radio signal characteristics and RF design
RF signal vulnerability to Interference dictates how much interference can be tolerated, and therefore how far apart same-frequency cells must be spaced
For a specific S/N level, the Signal Bandwidth determines how many RF signals will “fit” in the operator’s licensed spectrum
AMPS, D-AMPS, N-AMPS
CDMA
30 30 10 kHz
200 kHz
1250 kHz
1 3 1 Users
8 Users
22 Users1
1
11
1
11
11
1
11
1
1
12
34
43
2
56
17
Typical Frequency Reuse N=7
Typical Frequency Reuse N=4
Typical Frequency Reuse N=1
Vulnerability:C/I @ 17 dB
Vulnerability:C/I @ 12-14 dB
Vulnerability:Eb/No @ 6 dB
GSM
17 dB = 101.7 @ 5014 dB = 101.4 @ 25 12 dB = 101.2 @ 16
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 30
Relationship Between Eb/N0 and S/N
Eb =S
R
Signal Power
Bit Rate = N0 =
N
W
Noise Power
Bandwidth=
=S
R
W
N X =
S
N
W
R X
S
R
N
W
Eb
N0
=
Signal to Noise
ProcessingGain
E / t
B / t=
W
R=
1,250,000
14,400= 87 =
1.94
10 = 19.4dB
W
R=
1,250,000
9,600= 130 =
2.11
10 = 21.1dB8 Kb vocoder
(Full Rate)
13 Kb vocoder(Full Rate)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 31
S/N Advantage of CDMA
AMPS
N-AMPS
D-AMPS
GSM
CDMA
Analog FM
Analog FM
DQPSK
GMSK
QPSK/OQPSK
30 KHz.
10 KHz.
30 KHz.
200 KHz.
1,250 KHz.
C/I @ 17 dB
C/I @ 17 dB
C/I @ 17 dBC/I @ 12-14
dBEb/No @ 6dB
Tech-nology Modulation Type Channel
BandwidthQuality
Indicator
S/N @ 17 dB
S/N @ 17 dB
S/N @ 17 dB
S/N @ 12 to 14 dB
S/N @ –13.4 dB
S/N
17 dB = 101.7 @ 5014 dB = 101.4 @ 25 12 dB = 101.2 @ 16
-13.4 dB = 10-1.34 @ 0.046 =
S
NÞ 10 0.6
10 1.94= = 10 -1.34 = -13.4 dB
Signal to NoiseProcessing Gain (W/R)
S
NX = 10 0.610 1.94
Eb N0
122
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 32
Overlaying CDMA on an AMPS System
Each CDMA Channel: 1.250 MHz ÷ 30 kHz = 41.7 = ~41 AMPS channelsEach Guard Band: 260 kHz ÷ 30 kHz = 8.7 = ~9 AMPS channels
260 KHz 260 KHz1.25 MHz Nominal Bandwidth
Frequency
Po
we
r1.77 MHz
CDMA CARRIER
41 AMPS channels 41 AMPS channels
9 AMPSchannels
41 AMPS channels
41 AMPS channels
CDMA CDMA CDMA CDMA CDMA
AVAILABLE AVAILABLE
885 MHzMinimum Separation between AMPS/TDMA and CDMA center frequency:
(1,250 kHz ÷ 2) + 260 kHz = 885 kHz
TOTAL: 1.77 MHz ÷ 30 kHz = 59 AMPS channels
GUARDBAND
GUARDBAND
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 33
CDMA Frequency Channel Assignment
IS-95 RECOMMENDS TO START CDMA DEPLOYMENTWITH EITHER THE PRIMARY OR THE SECONDARY CHANNEL
1
334
667
991
1023
333
666
715
799
716
ChannelNumbers
A (non-Wireline) B (Wireline) A’A” B’
1013 31 73 115 157 199 241 283 384 426 468 510 552 594 636 691 777
CDMA A-Band Carriers CDMA B-Band Carriers
8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 9 9 8
* **** Requires frequency coordination with
non-cellular interferers
** Requires frequency coordination with A-band carrier
A Band Primary Channel 283A Band Secondary Channel 691
B Band Primary Channel 384B Band Secondary Channel 777
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 34
CDMA Frequency Clearing: A-band(N=7 Reuse Pattern)
To deploy a CDMA carrier centered on AMPS/TDMA Channel 283, AMPS/TDMA Channels 254 through 312, inclusive, must be cleared from the CDMA coverage area
The CDMA channel is implemented, centered on AMPS/TDMA Channel 283. The first usable AMPS/TDMA Channels (outside of the Guard Zone) are Channels 253 and 313
333 332 331 330 329 328 327 326 325 324 323 322 321 320 319 318 317 316 315 314 313
312 311 310 309 308 307 306 305 304 303 302 301 300 299 298 297 296 295 294 293 292
291 290 289 288 287 286 285 284 283 282 281 280 279 278 277 276 275 274 273 272 271
270 269 268 267 266 265 264 263 262 261 260 259 258 257 256 255 254 253 252 251 250
249 248 247 246 245 244 243 242 241 240 239 238 237 236 235 234 233 232 231 230 229
228 227 226 225 224 223 222 221 220 219 218 217 216 215 214 213 212 211 210 209 208
207 206 205 204 203 202 201 200 199 198 197 196 195 194 193 192 191 190 189 188 187
186 185 184 183 182 181 180 179 178 177 176 175 174 173 172 171 170 169 168 167 166
165 164 163 162 161 160 159 158 157 156 155 154 153 152 151 150 149 148 147 146 145
144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124
123 122 121 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 103
102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82
81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61
60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40
39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19
18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
1A 2A 3A 4A 5A 6A 7A 1B 2B 3B 4B 5B 6B 7B 1C 2C 3C 4C 5C 6C 7C
a b g
N = 7
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 35
Overlay Guard Zone Deployment
AMPS Only Cellsapprox 19 channels per sector
CDMA & AMPS Cellsapprox 16 channels per sector
one CDMA channel/carrier/frequency
( 42 + 9 + 9 ) ÷ 21 = 2.8 = ~3 AMPS channels must be cleared per sector in the CDMA & AMPS area and in the Guard Zone to make
room for the first CDMA channel/carrier/frequency
The Guard Zones are needed between CDMA and other systems because CDMA increases the noise floor for those systems
AMPS Only Cells (GUARD ZONE)approx 16 channels per cell
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 36
a b g
1A 2A 3A 4A 5A 6A 7A 1B 2B 3B 4B 5B 6B 7B 1C 2C 3C 4C 5C 6C 7C
334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354
355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375
376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396
397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417
418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438
439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459
460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480
481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501
502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522
523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543
544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564
565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585
586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606
607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627
628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648
649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666
N = 7
CDMA Frequency Clearing: B-band(N=7 Reuse Pattern)
To deploy a CDMA carrier centered on AMPS/TDMA Channel 384, AMPS/TDMA Channels 355 through 413, inclusive, must be cleared from the CDMA coverage area
The CDMA channel is implemented, centered on AMPS/TDMA Channel 384. The first usable AMPS/TDMA Channels (outside of the Guard Zone) are Channels 354 and 414
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 37
CDMA 800 MHz Cellular Spectrum Usage
All CDMA RF carriers are 1.25 MHz. wide· can serve ~22 users w/8 kb vocoder (~17 users w/13 kb vocoder)
The cellular spectrum of one operator is 12.5 MHz. wide. You’d expect that 10 CDMA carriers would fit. However, only 9 carriers can be used· operators must maintain a “token” AMPS presence for several years· “guard bands” are required at the edges of frequency blocks or any
frequency boundaries between CDMA/non-CDMA signals· no guard bands are required between adjacent CDMA carriers
Possible CDMA Center Freq. Assignments
Channel Numbers
Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)824MHz
849MHz
869MHz
894MHz
otherusesA” A”A B A’ B’
1 10 10 1.5 2.5
A B A’ B’
1 10 10 1.5 2.5
991
10231 333
334
666667
716717
799
991
10231 333
334
666667
716717
799
~300 kHz. “guard bands” possibly required if adjacent-frequency signals are non-CDMA (AMPS, TDMA, ESMR, etc.)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 38
Number of Voice Channels (As AMPS Channels Are Converted to Digital)
0
50
100
150
200
1 2 3 4 5 6 7 8 9 10S1
S4
AMPS
TDMA
13 kbpsCDMA
8 kbpsCDMA
Num
ber
of V
oice
Cha
nnel
s
Number of CDMA Carriers0 1 2 3 4 5 6 7 8 9
200
150
100
50
0
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 39
Overlaying CDMA on the 1900 MHz Band
Each CDMA Channel: 1.250 MHz ÷ 50 kHz = 25 channels
Each Guard Band: 260 kHz ÷ 50 kHz = 5.2 = ~5 channels
TOTAL: 1.77 MHz ÷ 50 kHz = 35.4 = ~ 35 channels
260 KHz 260 KHz1.25 MHz Nominal Bandwidth
Frequency
Po
we
r
1.77 MHz
CDMA CARRIER
Just as with the CDMA on AMPS overlay, a GUARD ZONE is also needed
GUARDBAND
GUARDBAND
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 40
CDMA PCS 1900 MHz Spectrum Usage
A, B, and C licenses can accommodate 11 CDMA RF channels in their 30 MHz of spectrum
D, E, and F licenses can accommodate 3 CDMA RF channels in their 10 MHz of spectrum
260 kHz guard bands are required on the edges of the PCS spectrum to ensure no interference occurs with other applications just outside the spectrum
Guard Bands
Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)1850 MHz
BTA
BTA
BTA
BTA
BTA
BTA
Paired Bands
MTA BTAMTABTA MTAMTA
1910 MHz
1930MHz
1990MHz
Data Voice
A D B E F C A D B E F C
15 51010 1515151515 555 55
Licensed Licensed
Unlicensed
0
Channel Numbers 299
300
400
699
700
800
900
1199 0
299300
400
699700
800
900
1199
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 41
Nortel CDMA System Architecture
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 42
Nortel CDMA System Architecture
BSC-BSMMTX BTS
CDSU DISCO
Ch. Card ACC
Sa
Sb
Sc
TFU1
GPSRBSM
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocodersSelectors
CDSU
CDSU
CDSU
CDSU
CDSU
CDSU
CMSLM
LPP LPPENET
DTCs
DMS-BUS
TxcvrA
TxcvrB
TxcvrC
RFFEA
RFFEB
RFFEC
TFU
GPSR
PSTN & Other MTXs
GPS GPS
IOC
Billing
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 43
Signal Flow: Two-Stage Metamorphosis
BSC-BSMMTX BTS
Ch. Card ACC
Sa
Sb
Sc
TFU1
GPSRBSM
CDSU
CDSU
SBSVocodersSelectors
CDSU
CDSU
CDSU
CDSU
CDSU
CMSLM
LPP LPPENET
DTCs
DMS-BUS
TxcvrA
TxcvrB
TxcvrC
RFFEA
RFFEB
RFFEC
TFU
GPSR
GPS GPS
IOC
PSTN
CDSU DISCOCDSU
DISCO 1
DISCO 2
DS0 in T1Packets
ChipsRFChannel
ElementVocoder
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 44
Architecture: The MTX
Primary functions· Call Processing· Mobility Management
- HLR-VLR access- Intersystem call delivery (IS-41C)- Inter-MTX handover (IS-41C)
· Billing Data Capture· Calling Features & Services· Collecting System OMs, Pegs
High reliability, redundancy
MTX
CMSLM
LPP ENET
DTCs
DMS-BUS
PSTN & Other MTXs
CDMABSC
Unch. T1
IOC
CDMASBS
MAP,VDUs
Billing
LPP
CCS7
Ch.T1
ChT1
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 45
Architecture: The BSC
Primary functions· vocoding· soft handoff management· FER-based power control· routing of all traffic and control
packets Scaleable architecture
· expand SBS to keep pace with traffic growth
· expandable DISCO
BSC
TFU1
GPSRBSM
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocodersSelectors
CDSU
CDSU
CDSU
CDSU
CDSU
CDSU
GPS
MTX(voicetrunks)
MTXLPP
BTSs
T1 channelized (24 DS0)T1 unchannelizedBCN link (HDLC)
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 46
Architecture: The BTS
Primary function: Air link · generate, radiate, receive CDMA RF
signal IS-95/J.Std. 8· high-efficiency T1 backhaul· test capabilities
Configurations· 1, 2, or 3 sectors· 800 MHz.: indoor· 1900 MHz.: self-contained outdoor,
remotable RFFEs· future: 1900 MHz. indoor, 800 & 1900
multi-carrier options
BTS
CDSU DISCO
Ch. Card ACC
Sa
Sb
Sc
TxcvrA
TxcvrB
TxcvrC
RFFEA
RFFEB
RFFEC
TFU
GPSR
GPS
BSC
Fundamentals of CDMA - Luis Font CDMA Technical Market Support, CALA & EMEA - Nov. 9, 1998 - Page 47
Architecture: The BSM
Primary functions: OA&M for CDMA components· Configuration management
- BSC, BTS configuration and parameters
· Fault management- Alarm Reporting
· Performance management- interface for CDMA statistics
and peg counts collection· Security management· Unix-based
BSC BTS
CDSU DISCO
Ch. Card ACC
Sa
Sb
Sc
TFU1
GPSR
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocodersSelectors
CDSU
CDSU
CDSU
CDSU
CDSU
CDSU
TxcvrA
TxcvrB
TxcvrC
RFFEA
RFFEB
RFFEC
TFU
GPSR
GPS GPS
BSM
X-Windows terminals
Ethernet LAN
BSM Workstation
GNP TELCOWORKSERVER
SHELF---------HIGH
AVAILABILITY
NORTEL CDMA BSM
BCN Links