cdma networks intro
TRANSCRIPT
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Current CDMA NetworksArchitectures, Algorithms, & Performance
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Section A
CDMA Principles Review
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CDMA: Using A New Dimension
All CDMA users occupy the same frequencyat the same time! Frequency and time arenot used as discriminators
CDMA operates by using CODING todiscriminate between users
CDMA interference comes mainly fromnearby users
Each user is a small voice in a roaringcrowd -- but with a uniquely recoverablecode
CDMA
Figure of Merit: C/I(carrier/interference ratio)
AMPS: +17 dB
TDMA: +14 to +17 dBGSM: +7 to 9 dB.
CDMA: -10 to -17 dB.CDMA: Eb/No ~+6 dB.
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DSSS Spreading: Time-Domain View
At Originating Site: Input A: Users Data @
19,200 bits/second
Input B: Walsh Code #23@ 1.2288 Mcps
Output: Spread
spectrum signal
At Destination Site: Input A: Received
spread spectrum signal
Input B: Walsh Code #23@ 1.2288 Mcps
Output: Users Data @19,200 bits/second justas originally sent
Drawn to actual scale and time alignment
via air interface
XORExclusive-OR
Gate
1
1
Input A: Received Signal
Input B: Spreading Code
Output: Users Original Data
Input A: Users Data
Input B: Spreading Code
Spread Spectrum Signal
XORExclusive-OR
Gate
Originating Site
Destination Site
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Spreading from a Frequency-Domain View
Traditional technologies tryto squeeze signal intominimum requiredbandwidth
CDMA uses largerbandwidth but usesresulting processing gain toincrease capacity
Spread Spectrum Payoff:Processing Gain
Spread Spectrum
TRADITIONAL COMMUNICATIONS SYSTEM
SlowInformation
Sent
TX
SlowInformationRecovered
RX
NarrowbandSignal
SPREAD-SPECTRUM SYSTEM
Fast
SpreadingSequence
SlowInformation
Sent
TX
SlowInformationRecovered
RX
Fast
SpreadingSequence
WidebandSignal
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CDMA Uses Code Channels
The purpose of a CDMA system is to transmit bitsfrom one user to another
Vocoder bits are the payload in voice calls
Fax or Web TCP/IP data bits are also possible
A CDMA signal uses many chips to convey just
one bit of information
Each user has a unique chip pattern, in effect achannel made from codes
To recover a bit, integrate a large number of chipsinterpreted by the users known code pattern
Other users code patterns appear random andadd up in a random self-canceling fashion; theydont disturb the bit decoding decision beingmade regarding information transmitted on theproper code pattern
Building aCDMA Signal
Bitsfrom Users Vocoder
Symbols
Chips
Forward ErrorCorrection
Coding and
Spreading
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Sneak Preview: How One Traffic ChannelIs Transmitted by One Sector to a Mobile
S
if 1 =if 0 =
1
AnalogSummingUsers
QPSK RF
S
DemodulatedReceived
CDMA Signal
Despreading Sequence(Locally Generated, =0)
matches
opposite
Decision:
Matches!( = 0 )
TimeIntegration
1
Opposite( =1)
+10
-26
Received energy: Correlation
-16
BTS
This figure illustrates the basic technique ofCDMA signalgeneration at the sector and recovery at the mobile.The complete coding process uses two additional codes,
as described in following slides.
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Spreading: What we do, we can undo
Sender combines data with a fast spreading sequence, transmits
spread data stream Receiver intercepts the stream, uses same spreading sequence
to extract original data
ORIGINATING SITE DESTINATION
SpreadingSequence
SpreadingSequence
InputData
RecoveredData
Spread Data Stream
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Shipping and Receiving via CDMA
Whether in shipping and receiving, or in CDMA, packaging isextremely important!
Cargo is placed inside nested containers for protection and toallow addressing
The shipper packs in a certain order, and the receiver unpacks in
the reverse order CDMA containers are spreading codes
FedEx
Data Mailer
FedEx
DataMailer
Shipping Receiving
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CDMAs 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
What we do, we can undo
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
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One of the CDMA Spreading Sequences:Walsh Codes
64 Magic Sequences, each 64 chips long Each Walsh Code is precisely Orthogonal with
respect to all other Walsh Codes
its simple to generate the codes, or
theyre small enough to use from ROM
WALSH CODES# ------------------- --------------- 64-Chip Sequence ----------------------------------------- -0 00000000000000000000000000000000000000000000000000000000000000001 01010101010101010101010101010101010101010101010101010101010101012 0011001100110011001100110011001100110011001100110011001100110011
3 01100110011001100110011001100110011001100110011001100110011001104 00001111000011110000111100001111000011110000111100001111000011115 01011010010110100101101001011010010110100101101001011010010110106 00111100001111000011110000111100001111000011110000111100001111007 01101001011010010110100101101001011010010110100101101001011010018 00000000111111110000000011111111000000001111111100000000111111119 0101010110101010010101011010101001010101101010100101010110101010
10 001100111100110000110011110011000011001111001100001100111100110011 011001101001100101100110100110010110011010011001011001101001100112 000011111111000000001111111100000000111111110000000011111111000013 010110101010010101011010101001010101101010100101010110101010010114 001111001100001100111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 010110100101101010100101101001010101101001011010101001011010010122 001111000011110011000011110000110011110000111100110000111100001123 0110100101101001100101101001011001101001011010011001011010010110
24 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 001100111100110000110011110011001100110000110011110011000011001143 011001101001100101100110100110011001100101100110100110010110011044 000011111111000000001111111100001111000000001111111100000000111145 010110101010010101011010101001011010010101011010101001010101101046 001111001100001100111100110000111100001100111100110000110011110047 011010011001011001101001100101101001011001101001100101100110100148 000000000000000011111111111111111111111111111111000000000000000049 010101010101010110101010101010101010101010101010010101010101010150 001100110011001111001100110011001100110011001100001100110011001151 011001100110011010011001100110011001100110011001011001100110011052 000011110000111111110000111100001111000011110000000011110000111153 010110100101101010100101101001011010010110100101010110100101101054 001111000011110011000011110000111100001111000011001111000011110055 011010010110100110010110100101101001011010010110011010010110100156 000000001111111111111111000000001111111100000000000000001111111157 010101011010101010101010010101011010101001010101010101011010101058 001100111100110011001100001100111100110000110011001100111100110059 011001101001100110011001011001101001100101100110011001101001100160 000011111111000011110000000011111111000000001111000011111111000061 010110101010010110100101010110101010010101011010010110101010010162 001111001100001111000011001111001100001100111100001111001100001163 0110100110010110100101100110100110010110011010010110100110010110
EXAMPLE:
Correlation of Walsh Code #23 with Walsh Code #59
#23 0110100101101001100101101001011001101001011010011001011010010110
#59 0110011010011001100110010110011010011001011001100110011010011001
Sum 0000111111110000000011111111000011110000000011111111000000001111
Correlation Results: 32 1s, 32 0s: Orthogonal!!
Unique Propert ies:
Mutual Orthogonality
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Other Sequences: Generation & Properties
Other CDMA sequences aregenerated in shift registers
Plain shift register: no fun,sequence = length of register
Tapped shift register generates a
wild, self-mutating sequence 2N
-1chips long (N=register length)
Such sequences match ifcompared in step (no-brainer,any sequence matches itself)
Such sequences appearapproximately orthogonal ifcompared with themselves notexactly matched in time
false correlation typically
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Another CDMA Spreading Sequence:The Short PN Code
The short PN code consists of twoPN Sequences, I and Q, each32,768 chips long
Generated in similar butdifferently-tapped 15-bit shift
registers Theyre always used together,
modulating the two phase axesof a QPSK modulator
IQ
32,768 chips long26-2/3 ms.
(75 repetitions in 2 sec.)CDMA QPSK Phase ModulatorUsing I and Q PN Sequences
I-sequence
Q-sequence
S
cos wt
sin wt
chip
input
QPSK-modulated
RFOutput
*
* In BTS, I and Q are used in-phase.In handset, Q is delayed 1/2 chip toavoid zero-amplitude crossings whichwould require a linear power amplifier
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Third CDMA Spreading Sequence: Long CodeGeneration & Masking to establish Offset
Generated in a 42-bit register, the PN Long code is more than 40 days long(~4x1013 chips) -- too big to store in ROM in a handset, so its generated chip-by-chip using the scheme shown above
Each handset codes its signal with the PN Long Code, but at a unique offset
computed using its ESN (32 bits) and 10 bits set by the system this is called the Public Long Code Mask; produces unique shift
private long code masks are available for enhanced privacy
Integrated over a period even as short as 64 chips, phones with different PNlong code offsets will appear practically orthogonal
Long Code Register(@ 1.2288 MCPS)
Public Long Code Mask(STATIC)
User Long CodeSequence(@1.2288 MCPS)
1 1 0 0 0 1 1 0 0 0 P E RMU T E D E S NAND
=S UM
Modulo-2 Addition
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Putting it All Together: CDMA Channels
The three spreading codes are used in different ways to create theforward and reverse links
A forward channel exists by having a specific Walsh Code assigned to theuser, and a specific PN offset for the sector
A reverse channel exists because the mobile uses a specific offset of theLong PN sequence
BTS
WALSH CODE: Individual UserSHORT PN OFFSET: Sector
LONG CODE OFFSET:
individual handset
FORWARD CHANNELS
REVERSE CHANNELS
LONG CODE:DataScrambling
WALSH CODES:
used as symbolsfor robustness
SHORT PN:used at 0 offset
for tracking
OneSector
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Section B
IS-95 CDMA Forward andReverse Channels
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How a BTS Builds the Forward Code Channels
BSCor
AccessManager
BTS (1 sector)
FECWalsh #1
Sync FECWalsh #32
FECWalsh #0
FECWalsh #12
FECWalsh #27
FECWalsh #44
Pilot
Paging
Vocoder
Vocoder
Vocoder
Vocoder
more more
Short PN Code
PN Offset 246
Trans-mitter,
Sector X
Switch
more
a Channel Element
A Forward Channelis identified by:
its CDMA RFcarrierFrequency
the unique Short
Code PN Offset ofthe sector
the unique WalshCode of the user
FECWalsh #23
SQ
SI
x
x
+
coswt
s inwt
I Q
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Functions of the CDMA Forward Channels
PILOT: WALSH CODE 0
The Pilot is a structural beacon whichdoes not contain a character stream. It is atiming source used in system acquisitionand as a measurement device duringhandoffs
SYNC: WALSH CODE 32 This carries a data stream of system
identification and parameter informationused 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 parametersinformation, and call setup orders
TRAFFIC: any remaining WALSH codes The traffic channels are assigned to
individual users to carry call traffic. Allremaining Walsh codes are available,subject to overall capacity limited by noise
Pilot Walsh 0
Walsh 19
Paging Walsh 1
Walsh 6
Walsh 11
Walsh 20Sync Walsh 32
Walsh 42
Walsh 37
Walsh 41
Walsh 56
Walsh 60
Walsh 55
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Code Channels in the Reverse Direction
BSC,CBSC,
AccessManager
Switch BTS (1 sector)
Channel Element
Access Channels
Vocoder
Vocoder
Vocoder
Vocoder
more more
Receiver,Sector X
A Reverse Channel is identified by:
its CDMA RF carrierFrequency
the unique Long Code PN Offsetof the individual handset
Channel Element
Channel Element
Channel Element
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
more
a Channel Element
Long
Codeoffset LongCodeoffset Long
Codeoffset
LongCodeoffset
Long
Codeoffset
LongCodeoffset
Channel Element
Long Code Gen
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REG
1-800
242
4444
BTS
Although a sector can have up to seven paging channels, and each paging channelcan have up to 32 access channels, nearly all systems today use only one paging
channel per sector and only one access channel per paging channel.
Functions of the CDMA Reverse Channels
There are two types of CDMA Reverse Channels:
TRAFFIC CHANNELS are used by individual usersduring their actual calls to transmit traffic to the BTS
a reverse traffic channel is really just a user-specific public or private Long Code mask
there are as many reverse Traffic Channels asthere are CDMA phones in the world!
ACCESS CHANNELS are used by mobiles not yetin a call to transmit registration requests, call setuprequests, page responses, order responses, andother signaling information
an access channel is really just a public longcode offset unique to the BTS sector
Access channels are paired to Paging Channels.Each paging channel can have up to 32 accesschannels.
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Basic CDMA Network Architecture
Access Manageror (C)BSCSwitch 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 T1
PacketsChips
RFChannelElementVocoder
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Forward Traffic Channel:Generation Details from IS-95
Walsh
function
PowerControl
Bit
I PN
9600bps4800 bps
2400 bps
1200 bps
or
14400 bps7200 bps
3600 bps
1800 bps
(From Vocoder)
Convolutional
Encodingand
Repetition SymbolPuncturing
(13 kb only)
1.2288
McpsLong PN Code
Generation
19.2ksps
800Hz
R=1/2
QPN
Decimator DecimatorUserAddress
Mask
(ESN-based)
19.2ksps
1.2288
McpsScrambling
bi ts symbols ch ips
19.2ksps
28.8ksps
CHANNEL ELEMENT
M
U
X
Block
Interleaving
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Reverse Traffic Channel:Generation Details from IS-95
9600 bps4800 bps2400 bps1200 bps
or
14400 bps
7200 bps3600 bps1800 bps
28.8ksps
R = 1/3
1.2288McpsUser Address
Mask
LongPN Code
Generator
28.8ksps
Orthogonal
Modulation
Data BurstRandomizer
307.2kcps
1.2288Mcps
QPN(no offset)
IPN(no offset)
D
1/2 PNChipDelay
DirectSequenceSpreading
R = 1/2
Convolutional
Encoder &
Repetition
Block
Interleaver
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Section C
IS-95 Operational DetailsVocoding, Multiplexing, Power Control
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Variable Rate Vocoding & Multiplexing
Vocoders compress speech, reduce bitrate, greatly increasing capacity
CDMA uses a superior Variable RateVocoder
full rate during speech
low rates in speech pauses increased capacity
more natural sound
Voice, signaling, and user secondarydata may be mixed in CDMA frames
DSP QCELP VOCODER
Codebook
PitchFilter
FormantFilter
Coded Result Feed-back
20ms Sample
Frame Sizesbits
Full Rate Frame
1/2 Rate Frame
1/4 Rt.
1/836
72
144
288
Frame Contents: can be a mixture of
Voice Signaling Secondary
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Forward Power Control
The BTS continually reduces the strength of each users forwardbaseband chip stream
When a particular handset sees errors on the forward link, itrequests more energy
The complainers chip stream gets a quick boost; afterward,continues to diminish
Each network manufacturer uses FER-based triggers and initial,minimum, and maximum traffic channel DGU values
ForwardRF
BSC BTS (1 sector)
Sync
Pilot
Paging
more
Short PN
Trans-mitter,
Sector XS I QUser 1User 2
User 3Vocoder/Selector
Help!
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Reverse Power Control
Three methods work in tandem to equalize all handset signal levelsat the BTS
Reverse Open Loop: handset adjusts power up or down basedon received BTS signal (AGC)
Reverse ClosedLoop: Is handset too strong? BTS tells up ordown 1 dB 800 times/second
Reverse OuterLoop: BSC has FER trouble hearing handset?BSC adjusts BTS setpoint
RX RF
TX RF Digital
BTSBSC
SetpointBad FER?
Raise Setpoint
Stronger thansetpoint?
ReverseRF
800 bits per second
Occasionally,
as needed
Handset
OpenLoop
Closed
Loop
Digital
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Details of Reverse Link Power Control
TXPO Handset Transmit Power
Actual RF power output of thehandset transmitter, includingcombined effects ofopen looppower control from receiverAGC andclosed loop powercontrol by BTS
cant exceed handsets maximum
(typ. +23 dBm)
TXGA Transmit Gain Adjust
Sum of all closed-loop power
control commands from the BTSsince the beginning of this call
TXPO
DUP x IFLNA
Subscriber Handset
R
R
R
S
Rake
S ViterbiDecoder
Vocoder
~
FECOrthMod
Long PN
x
x
x
IF Mod
I
Q
x ~LO
Open Loop
LO
Closed Loop Pwr Ctrl
IF
Receiver>>
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Course 134
CDMA Air Interface Capacity
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The Basic CDMA Capacity Equation
As this spreadsheet shows, actual traffic capacity is influencedstrongly by the degree of soft handoff actually in progress
Basic Capacity of a CDMA Cell
Case A Case B
Vocoder or Data Rate, kb/s 9.6 14.4 (9.6 for Rate Set 1, 14.4 for Rate Set 2)
Bandwidth, MHz. 1.25 1.25 (IS-95/J-Std 008 is 1.25 MHz.)
Eb/No in dB 7 7 5.01 Eb/No as ratio
Voice Duty fac tor 0.40 0.40 100% when talk ing, 12.5% when lis tening
Freq Reuse Efficiency 0.60 0.60 fraction of energy coming from within same cell
Sectorizat ion Gain 2.55 2.55 (2.55 observed for 3-sector cells in tests)
Gross Number of Users/Cell 99.4 66.2
Percentage of Users in Soft Handoff 50% 50%
Net Unique Users Per Cell 66.2 44.2
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Capacity Issues with Current CDMA Networks
Today, CDMA networks for the most part are still single-carrier this severely limits the capacity of one BTS to approximately 20
erlangs
implementing additional carriers brings logistical problemsinvolving handoffs and system acquisition by mobiles
Multiple-carrier operation is essential to achieve reasonablecapacities
Within networks, there are strategies for squeezing the most out ofoverloaded single-carrier BTSs. Some of the main points are:
reduce Pilot, Sync, and Paging levels as low as possible,
thereby gaining precious additional energy for traffic channels reduce BTS traffic channel DGU settings as low as possible
without provoking forward link FER.
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Wireless System Capacity Comparisons
Each wireless technology (AMPS,NAMPS, D-AMPS, GSM, CDMA)uses a specific modulation typewith its own unique signalcharacteristics
Signal Bandwidth determineshow many RF signals will fit inthe operators licensed spectrum
Robustness of RF signaldetermines tolerable level ofinterference and necessaryphysical separation of cochannelcells
Number of users per RF signaldirectly affects capacity
In the following page, we willdevelop the number of users andtraffic in erlangs per site for eachof the popular wirelesstechnologies
AMPS, D-AMPS, N-AMPS
CDMA
30 30 10 kHz Bandwidth
200 kHz
1250 kHz
1 3 1 Users
8 Users
22 Users1
1
11
1
11
11
1
1 1 1
1
12
34
4
32
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 @ 6.5-9 dB
Vulnerability:EbNo@ 6 dB
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Comparison of Wireless System Capacities
Fwd/Rev Spectrum kHz. 12,500 12,500 12,500 15,000 15,000 15,000 5,000 5,000 5,000
Technology AMPS TDMA CDMA TDMA GSM CDMA TDMA GSM CDMA
Req'd C/I or Eb/No, db 17 17 6 17 12 6 17 12 6
Freq Reuse Factor, N 7 7 1 7 4 1 7 4 1
RF Signal BW, kHz 30 30 1250 30 200 1250 30 200 1250
Total # RF Carriers 416 416 9 500 75 11 166 25 3
RF Sigs. per cell @N 59 59 9 71 18 11 23 6 3
# Sectors per cell 3 3 3 3 3 3 3 3 3#CCH per sector 1 1 0 1 0 0 1 0 0
RF Signals per sector 18 18 9 22 6 11 6 2 3
Voicepaths/RF signal 1 3 22 3 8 22 3 8 22
SH average links used 1.66 1.66 1.66
Unique Voicepaths/carrier 13.253 13.253 13.253
Voicepaths/Sector 18 54 198 66 48 242 18 16 66
Unique Voicepaths/Sector 18 54 119 66 48 145 18 16 39
P.02 Erlangs per sector 11.5 44 105.5 55.3 38.4 130.9 11.5 9.83 30.1
P.02 Erlangs per site 34.5 132 316.5 165.9 115.2 392.7 34.5 29.49 90.3
Capacity vs. AMPS800 1 3.8 9.2 4.8 3.3 11.4 1.0 0.9 2.6
800 Cellular (A,B) 1900 PCS (A, B, C) 1900 PCS (D, E, F)
824 835 845 870 880
8
9
4
869
849
846.5825
8
9
0
891.5
Paging, ESMR, etc.A B A B
A D B E F C unlic.dataunlic.voice A D B E F C
1850MHz.
1910MHz.
1990MHz.
1930MHz.
15 15 155 5 5 15 15 155 5 5
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Multicarrier CDMA Capacity Implications
Fwd/Rev Spectrum kHz. 12,500 1,800 3,050 4,300 5,550 6,800 8,050 9,300 10,550 11,800 13,050 14,300
Technology AMPS CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA
Req'd C/I or Eb/No, db 17 6 6 6 6 6 6 6 6 6 6 6
Freq Reuse Factor, N 7 1 1 1 1 1 1 1 1 1 1 1
RF Signal BW, kHz 30 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250
Total # RF Carriers 416 1 2 3 4 5 6 7 8 9 10 11
RF Sigs. per cell @N 59 1 2 3 4 5 6 7 8 9 10 11
# Sectors per cell 3 3 3 3 3 3 3 3 3 3 3 3
#CCH per sector 1 0 0 0 0 0 0 0 0 0 0 0
RF Signals per sector 18 1 2 3 4 5 6 7 8 9 10 11
Voicepaths/RF signal 1 22 22 22 22 22 22 22 22 22 22 22
SH average links used 1 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66Unique Voicepaths/carrier 1 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3
Voicepaths/Sector 18 22 44 66 88 110 132 154 176 198 220 242
Unique Voicepaths/Sector 18 13 26 39 53 66 79 92 106 119 132 145
P.02 Erlangs per sector 11.5 7.4 18.4 30.1 43.1 55.3 67.7 80.2 93.8 105.5 119.1 130.9
P.02 Erlangs per site 34.5 22.2 55.2 90.3 129.3 165.9 203.1 240.6 281.4 316.5 357.3 392.7
Capacity vs. AMPS800 1 0.64 1.60 2.6 3.7 4.8 5.9 7.0 8.2 9.2 10.4 11.4
f
1 2 3 4 5 6 7 8 9 10 11
CDMA Carrier Frequencies
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Course 134
Nortel CDMA NetworkArchitecture
www.nortel.com
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Page 36Course 134v1.7 (c) 2011 AA
BASE STATION
CONTROLLER
SUPPORT
FUNCTIONS
BASE STATIONS
Mobile TelephoneSwitching Office
PSTN
Local Carriers
Long Distance
CarriersATM Link
to other CDMA
Networks
(Future)
Structure of a Typical Wireless System
Voice Mail System SWITCH
HLR Home Location Register
(subscriber database)
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Signal Flow: Two-Stage Metamorphosis
BSC-BSMMTX BTS
Ch. Card ACC
Sa
Sb
Sc
TFU1
GPSRBSM
CDSU
CDSU
SBS
VocodersSelectors
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 T1
PacketsChips
RFChannelElementVocoder
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Page 38Course 134v1.7 (c) 2011 AA
NORTEL CDMA System Architecture
BSC-BSMMTX BTS
CDSU DISCO
Ch. Card ACC
SaSbSc
TFU1
GPSRBSM
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocoders
Selectors
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 Current Product Capabilities:Each BSC can have up to 4 DISCO shelves
About 240 sites, roughly 6000 erlangs capacityEach MTX can have up to 2 BSCs
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Page 39Course 134v1.7 (c) 2011 AA
Switch: The Nortel 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
CDMABSCUnch. T1
IOC
CDMASBS
MAP,VDUs
Billing
LPP
CCS7
Ch.T1
ChT1
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Page 40Course 134v1.7 (c) 2011 AA
The Nortel BSC
Primary functions
vocoding
soft handoff management
FER-based power control
routing of all traffic and controlpackets
Scaleable architecture
expand SBS to keep pace withtraffic growth
expandable DISCO
BSC
TFU1
GPSRBSM
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocoders
Selectors
CDSU
CDSU
CDSU
CDSU
CDSU
CDSU
GPS
MTX(voice
trunks)
MTXLPP
BTSs
T1 channelized (24 DS0)
T1 unchannelized
BCN link (HDLC)
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Page 41Course 134v1.7 (c) 2011 AA
The Nortel BTS
Base Transceiver Station
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 new indoor, 800 MHz. & 1900 MHz.
multi-carrier options
Metrocell
BTS
CDSU DISCO
Ch. Card ACC
SaSbSc
TxcvrA
TxcvrB
TxcvrC
RFFEA
RFFEB
RFFEC
TFU
GPSR
GPS
BSC
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Page 42Course 134v1.7 (c) 2011 AA
The Nortel BSM
Base Station Manager
Primary functions: OA&M for CDMAcomponents
Configuration management
BSC, BTS configuration andparameters
Fault managementAlarm Reporting
Performance management
interface for CDMA statisticsand peg counts collection
Security management
Unix-based
BSC BTS
CDSU DISCO
Ch. Card ACC
SaSbSc
TFU1
GPSR
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocoders
Selectors
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 TELCO
WORKSERVER
SHELF---------
HIGHAVAILABILITY
NORTEL CDMABSM
BCN Links
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Page 43Course 134v1.7 (c) 2011 AA
Nortel Operational Capacity Considerations
BSC-BSMMTX BTS
Ch. Card ACC
Sa
Sb
Sc
TFU1
GPSRBSM
CDSU
CDSU
SBSVocoders
Selectors
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
Sufficient vocoders/selectorsrequired in BSC SBS, one persimultaneous call on the system.
8 Vocoders per SBS card, 12cards per shelf, 4 shelves per
SBS cabinet.
One T-1 can carry alltraffic originated by a
one-carrier BTS; specialconsideration required if
daisy-chaining
Forward RF Capacity:links use available
BTS TX power
Sufficient channelelements required fortraffic of all sectors:one CE per link; 20
CE per Channel Card
64 Walsh Codes/sector
64 Walsh Codes/sector
64 Walsh Codes/sector
DISCO has192 ports
max. Each
BTS uses 1,SBS shelf 1,LPP CIU 1,
Link 2, Ctrl. 2,BSM 4.
Typical CM processorcapacity considerations
PSTN trunk groups mustbe dimensioned to
support erlang load.
DTC & ENET:One port perVocoder plusone port per
outgoing trunk.
CDMA LPP:One pairCIUs andOne pairCAUs per
approx. 600erlangs
Reverse RF Capacity:links cause noise floorrise, use mobile power
1-2001 Current Product Capabilities:Each BSC can have up to 4 DISCO shelves
About 240 sites, roughly 6000 erlangs capacityEach MTX can have up to 2 BSCs
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Page 44Course 134v1.7 (c) 2011 AA
Course 134
CDMA Handset Architecture
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Page 45Course 134v1.7 (c) 2011 AA
Functional Anatomy of a CDMA Handset
Duplexer &Bandpass
Filters
IFBPF
MixerLNA
LocalOscillator
(Synthesized)
ViterbiDecoder
Vocoder
Search Correlator (Pilots)
PN Generator Walsh=0
IF
CPU &Control
Algorithms
VocoderConv. Encoder& Symbol Rep.
BlockInterleaver
OrthogonalModulator
Data BurstRandomizer
Direct Seq.Spreading
QuadratureSpreading
BasebandFiltering
IFModulator
PowerAmplifier
IF
Antenna
Receiver
Transmitter
bi ts
bi tsaudio
audio
symbolsch ips
Mixer
ch ips symbols symbols
RF IF
RF
RF
LO
LO
IF
Open Loop Pwr Control
messages
messagesLONG CODE Generator
IF
IF Transm it Gain Adjust : Closed Loop Pwr Control
Traffic Correlator
PN Generator Walsh Generator
Traffic Correlator
PN Generator Walsh Generator
Traffic Correlator
PN Generator Walsh Generator
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Page 46Course 134v1.7 (c) 2011 AA
The Rake Receiver
Every frame, handset uses combined outputs of the three trafficcorrelators (rake fingers)
Each finger can independently recover a particular PN offset andWalsh code
Fingers can be targeted on delayed multipath reflections, or even ondifferent BTSs
Searcher continuously checks pilots
Handset Rake Receiver
RFPN WalshPN Walsh
PN Walsh
SearcherPN W=0
SVoice,Data,
Messages
Pilot Ec/Io
BTS
BTS
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Page 47Course 134v1.7 (c) 2011 AA
CDMA Soft Handoff Mechanics
CDMA soft handoff is driven by the handset
Handset continuously checks available pilots
Handset tells system pilots it currently sees
System assigns sectors (up to 6 max.), tells handset
Handset assigns its fingers accordingly
All messages sent by dim-and-burst, no muting! Each end of the link chooses what works best, on a frame-by-frame
basis!
Users are totally unaware of handoff
Handset Rake Receiver
RF
PN Walsh
PN Walsh
PN Walsh
SearcherPN W=0
S Voice,Data,Messages
Pilot Ec/Io
BTS
BSCSwitch
BTS
Sel.
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Adventures in Call Processing5 Minutes in the Life of a CDMA Handset
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Page 49Course 134v1.7 (c) 2011 AA
Our Call Processing Adventures
Layer-3 Messaging Review Lets Acquire the System!
Lets do an Idle Mode Handoff!
Lets Register!
Lets Receive an Incoming Call!
Lets Make an Outgoing Call!
Lets End a Call!
Lets Receive Notification of a Voice Message!
Lets Do a Handoff!
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Layer-3 Messaging Review
CDMA Call Processing
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Page 51Course 134v1.7 (c) 2011 AA
How CDMA Messages are Sent
CDMA messages on both forwardand reverse traffic channels arenormally sent via dim-and-burst
Messages include many fields ofbinary data
The first byte of each messageidentifies message type: this allows
the recipient to parse the contents To ensure no messages are
missed, all CDMA messages bearserial numbers and importantmessages contain a bit requestingacknowledgment
Messages not promptlyacknowledged are retransmittedseveral times. If not acknowledged,the sender may release the call
Field data processing tools captureand display the messages for study
MSG_TYPE (00000110)
ACK_SEQ
MSG_SEQ
ACK_REQ
ENCRYPTION
ERRORS_DETECTED
POWER_MEAS_FRAMES
LAST_HDM_SEQ
NUM_PILOTS
PILOT_STRENGTH
RESERVED (0s)
8
3
3
1
2
5
10
2
4
6
0-7
NUM_PILOTS occurrences of this field:
Field Length
(in bits)
EXAMPLE:
A POWER MEASUREMENT
REPORT MESSAGE
t
Message Vocabulary: Acquisition & Idle States
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Message Vocabulary: Acquisition & Idle States
Sync Channel
Sync Channel Msg
Pilot Channel
No Messages
Paging Channel
Access Parameters Msg
System Parameters Msg
CDMA Channel List Msg
Extended SystemParameters Msg
Extended NeighborList Msg
Global ServiceRedirection Msg
Order MsgBase Station Acknowledgment
Lock until Power-Cycled Maintenance required
many others..
AuthenticationChallenge Msg
Status Request Msg
Feature Notification Msg
TMSI Assignment Msg
Channel AssignmentMsg
SSD UpDate 2011Msg
Service Redirection Msg
General Page Msg
Null Msg Data Burst Msg
Access Channel
Registration Msg
Order MsgMobile Station Acknowldgment
Long Code Transition RequestSSD UpDate 2011Confirmation
many others..
Origination Msg
Page Response Msg
Authentication ChallengeResponse Msg
Status Response Msg
TMSI AssignmentCompletion Message
Data Burst Msg
BTS
M V b l C ti St t
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Message Vocabulary: Conversation State
Reverse Traffic Channel
Order Message
Mobile Sta. Acknowledgment
Long Code TransitionRequest
SSD UpDate 2011Confirmation
Connect
Authentication ChallengeResponse Msg
Flash WithInformation Msg
Data Burst Message
Pilot StrengthMeasurement Msg
Power MeasurementReport Msg
Send Burst DTMF Msg
OriginationContinuation Msg
Handoff Completion Msg
Parameters ResponseMessage
Service Request Msg
Service Response Msg
Service ConnectCompletion Message
Service Option ControlMessage
Status Response Msg
TMSI AssignmentCompletion Message
Forward Traffic Channel
Order Msg
Base Station AcknowledgmentBase Station ChallengeConfirmation
Message Encryption Mode
AuthenticationChallenge Msg
Alert WithInformation Msg
Data Burst Msg
Analog HandoffDirection Msg
In-Traffic SystemParameters Msg
Neighbor ListUpDate 2011Msg
Send Burst DTMF Msg
Power ControlParameters Msg.
Retrieve Parameters Msg
Set Parameters Msg
SSD UpDate 2011Msg
Flash WithInformation Msg
Mobile StationRegistered Msg
Status Request Msg
Extended HandoffDirection Msg
Service Request Msg
Service Response Msg
Service Connect Msg
Service OptionControl Msg
TMSI Assignment Msg
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Page 54Course 134v1.7 (c) 2011 AA
Lets Acquire the System!
CDMA Call Processing
Fi d F ith CDMA RF Si l
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Page 55Course 134v1.7 (c) 2011 AA
Find a Frequency with a CDMA RF Signal
Mobile scans forward link frequencies:
(Cellular or PCS, depending on model)
History ListPreferred Roaming List
until a CDMA signal is found.NO CDMA?! Go to AMPS,
or to a power-saving standby mode
HISTORY
LIST
Last-used:
Freq/SID x
Freq/SID y
Freq/SID z
Freq/SID t
Freq/SID u
etc.
FREQUENCY LISTS:
PREFERRED
ROAMING
LIST
Freq/SID 1
Freq/SID 2
Freq/SID 3
Freq/SID 4
Freq/SID 5
etc.
Forward Link Frequencies(Base Station Transmit)
A D B E F C unlic.data unlic.voice A D B E F C
1850MHz. 1910MHz. 1990 MHz.1930MHz.
1900 MHz. PCS Spectrum
824 MHz. 835 845 870 880 894
869
849
846.5825
890
891.5
Paging, ESMR, etc.A B A B
800 MHz. Cellular Spectrum
Reverse Link Frequencies(Mobile Transmit)
Fi d St t Pil t R d S Ch l
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Find Strongest Pilot, Read Sync Channel
Rake FingersReference PN
Active Pilot
E
c/Io
00
32K512
ChipsPN
1. Pilot SearcherScans the Entire Range of PNs
All PN Offsets0
-20
98/05/24 23:14:09.817 [SCH]Sync Channel Message
MSG_LENGTH = 208 bits
MSG_TYPE = Sync Channel Message
P_REV = 3
MIN_P_REV = 2
SID = 179
NID = 0
PILOT_PN = 168 Offset Index
LC_STATE = 0x0348D60E013
SYS_TIME = 98/05/24 23:14:10.160
LP_SEC = 12
LTM_OFF = -300 minutes
DAYLT = 0
PRAT = 9600 bps
RESERVED = 1
2. Put Rake finger(s) on strongestavailable PN, decode Walsh 32,
and read Sync Channel Message
SYNC CHANNEL MESSAGE
Handset Rake Receiver
RF x
LO Srch PN??? W0
F1 PN168 W32
F2 PN168 W32
F3 PN168 W32
Th C fi ti M
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The Configuration Messages
After reading the Sync Channel, the mobile is now capable ofreading the Paging Channel, which now monitors constantly
Before it is allowed to transmit or operate on this system, themobile must collect a complete set of configuration messages
Collection is a short process -- all configuration messages arerepeated on the paging channel every 1.28 seconds
The configuration messages contain sequence numbers so themobile can recognize if any of the messages have been freshlyupdated as it continues to monitor the paging channel
Access parameters message sequence number
Configuration message sequence number
If a mobile notices a changed sequence number, or if 600seconds passes since the last time these messages were read,the mobile reads all of them again
G t P i Ch l G t C fi d
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Go to Paging Channel, Get Configured
Rake Fingers
Reference PN
Active Pilot
E
c/Io
00
32K512
ChipsPN
All PN Offsets0
-20
Keep Rake finger(s) on strongestavailable PN, decode Walsh 1,
and monitor the Paging Channel
Read theConfiguration Messages
Access Parameters Msg
System Parameters Msg
CDMA Channel List Msg
Extended SystemParameters Msg (*opt.)
(Extended*) NeighborList Msg
Global ServiceRedirection Msg (*opt.)
Now were ready to operate!!
Handset Rake Receiver
RF x
LO Srch PN??? W0
F1 PN168 W01
F2 PN168 W01
F3 PN168 W01
T V I t t C fi ti M
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Two Very Important Configuration Messages
98/05/24 23:14:10.427 [PCH]MSG_LENGTH = 184 bitsMSG_TYPE = Access Parameters MessagePILOT_PN = 168 Offset IndexACC_MSG_SEQ = 27ACC_CHAN = 1 channelNOM_PWR = 0 dBINIT_PWR = 0 dBPWR_STEP = 4 DbNUM_STEP = 5 Access Probes MaximumMAX_CAP_SZ = 4 Access Channel Frames Maximum
PAM_SZ = 3 Access Channel FramesPersist Val for Acc Overload Classes 0-9 = 0Persist Val for Acc Overload Class 10 = 0Persist Val for Acc Overload Class 11 = 0Persist Val for Acc Overload Class 12 = 0Persist Val for Acc Overload Class 13 = 0Persist Val for Acc Overload Class 14 = 0Persist Val for Acc Overload Class 15 = 0Persistance Modifier for Msg Tx = 1Persistance Modifier for Reg = 1Probe Randomization = 15 PN chips
Acknowledgement Timeout = 320 msProbe Backoff Range = 4 Slots MaximumProbe Sequence Backoff Range = 4 Slots Max.Max # Probe Seq for Requests = 2 SequencesMax # Probe Seq for Responses = 2 SequencesAuthentication Mode = 1Random Challenge Value = Field OmittedReserved Bits = 99
ACCESS PARAMETERS MESSAGE98/05/24 23:14:11.126 [PCH] System Parameter MessageMSG_LENGTH = 264 bitsMSG_TYPE = System Parameters MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0SID = 179 NID = 0REG_ZONE = 0 TOTAL_ZONES = 0 ZONE_TIMER = 60 minMULT_SIDS = 0 MULT_NID = 0 BASE_ID = 8710BASE_CLASS = Public MacrocellularPAGE_CHAN = 1 channelMAX_SLOT_CYCLE_INDEX = 0
HOME_REG = 0 FOR_SID_REG = 0 FOR_NID_REG = 1POWER_UP_REG = 0 POWER_DOWN_REG = 0PARAMETER_REG = 1 REG_PRD = 0.08 secBASE_LAT = 00D00'00.00N BASE_LONG = 000D00'00.00EREG_DIST = 0SRCH_WIN_A = 40 PN chipsSRCH_WIN_N = 80 PN chipsSRCH_WIN_R = 4 PN chipsNGHBR_MAX_AGE = 0PWR_REP_THRESH = 2 frames
PWR_REP_FRAMES = 56 framesPWR_THRESH_ENABLE = 1PWR_PERIOD_ENABLE = 0PWR_REP_DELAY = 20 framesRESCAN = 0T_ADD = -13.0 Db T_DROP = -15.0 dB T_COMP = 2.5 dBT_TDROP = 4 secEXT_SYS_PARAMETER = 1RESERVED = 0GLOBAL_REDIRECT = 0
SYSTEM PARAMETERS MESSAGE
F Additi l C fi ti M
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Four Additional Configuration Messages
98/05/24 23:14:10.946 [PCH]Extended System Parameters MessageMSG_LENGTH = 104 bitsMSG_TYPE = Extended System Parameters MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0 RESERVED = 0PREF_MSID_TYPE = IMSI and ESNMCC = 000 IMSI_11_12 = 00RESERVED_LEN = 8 bitsRESERVED_OCTETS = 0x00BCAST_INDEX = 0RESERVED = 0
EXTENDED SYSTEM PARAMETERS
98/05/17 24:21.566 Paging Channel: Global Service RedirectionPILOT_PN: 168, MSG_TYPE: 96, CONFIG_MSG_SEQ: 0Redirected access overload classes: { 0, 1 },RETURN_IF_FAIL: 0,DELETE_TMSI: 0,Redirection to an analog system:EXPECTED_SID = 0Do not ignore CDMA Available indicator on the redirected analogsystemAttempt service on either System A or B with the custom systemselection process
GLOBAL SERVICE REDIRECTION
98/05/24 23:14:11.486 [PCH] Neighbor List MessageMSG_LENGTH = 216 bitsMSG_TYPE = Neighbor List MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0PILOT_INC = 4 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 220 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 52 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 500 Offset Index
NGHBR_CONFIG = 0 NGHBR_PN = 8 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 176 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 304 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 136 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 384 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 216 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 68 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 328 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 112 Offset IndexRESERVED = 0
NEIGHBOR LIST
98/05/24 23:14:10.786 [PCH] CDMA Channel List MessageMSG_LENGTH = 72 bitsMSG_TYPE = CDMA Channel List MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0CDMA_FREQ = 283RESERVED = Field Omitted
CDMA CHANNEL LIST MESSAGE
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Lets do anIdle Mode Handoff!
CDMA Call Processing
Idl M d H d ff
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Page 62Course 134v1.7 (c) 2011 AA
Idle Mode Handoff
An idle mobile always demodulates the best available signal
In idle mode, it isnt possible to do soft handoff and listen tomultiple sectors or base stations at the same time -- the pagingchannel information stream is different on each sector, notsynchronous -- just as the TV news programs on differentnetworks are not in sync word-by-word if viewed together
Since a mobile cant combine signals, the mobile must switchquickly, always enjoying the best available signal
The mobiles pilot searcher is constantly checking neighbor pilots
If the searcher notices a better signal, the mobile continues on thecurrent paging channel until the end of the current superframe,then instantly switches to the paging channel of the new signal
The system doesnt know the mobile did this! (Does NBCsTom Brokaw know you just switched your TV to CNN?)
On the new paging channel, if the mobile learns that registration isrequired, it re-registers on the new sector
Idle Mode on the Paging Channel:
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g gMeet the Neighbors, track the Strongest Pilot
E
c/Io
All PN Offsets
00
32K512
ChipsPN
0
-20
Neighbor Set
The phones pilot searcher constantly checks
the pilots listed in the Neighbor List Message
If the searcher ever notices a neighbor pilot substantially stronger than
the current reference pilot, it becomes the new reference pilot
and the phone switches over to its paging channel on the next superframe.
This is called an id le mode handoff.
Rake Fingers
Reference PN
Active Pilot
SRCH_WIN_A
SRCH_WIN_N
Mobile Rake RX
Srch PN??? W0
F1 PN168 W01
F2 PN168 W01
F3 PN168 W01
Phone Operation on the Access Channel
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Page 64Course 134v1.7 (c) 2011 AA
Phone Operation on the Access Channel
A sectors Paging Channel announces 1(typ) to 32 (max) Access Channels: PN
Long Code offsets for mobiles to use ifaccessing the system. For mobiles sending Registration,
Origination, Page Responses Base Station always listening!
On the access channel, phones are notyet under BTS closed-loop power control!
Phones access the BTS by probing atpower levels determined by receive powerand an open loop formula
If probe not acknowledged by BTSwithin ACC_TMO (~400 mS.), phonewill wait a random time (~200 mS)then probe again, stronger by PI db.
There can be 15 max. (typ. 5) probesin a sequence and 15 max. (typ. 2)sequences in an access attempt
most attempts succeed on first probe! The Access Parameters message on the
paging channel announces values of allrelated parameters
ACCESS
RV TFC
BTS
Channel Assnmt. Msg.
Origination Msg
Base Sta. Acknlgmt. Order
TFC frames of 000s
TFC preamble of 000s
Base Sta. Acknlgmt. Order
Mobile Sta. Ackngmt. Order
Service Connect Msg.
Svc. Connect Complete Msg
Base Sta. Acknlgmt. Order
Call is Established!
MSProbing
PAGING
FW TFC
PAGING
RV TFC
FW FC
RV TFC
FW TFC
FW TFC
A Successful Access Attempt
a Probe Sequence
an Access Attempt
Success!
an Access Probe
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Lets Register!
CDMA Call Processing
Registration
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Registration
Registration is the process by which an idle mobile lets the systemknow its awake and available for incoming calls
this allows the system to inform the mobiles home switch ofthe mobiles current location, so that incoming calls can bedelivered
registration also allows the system to intelligently page the
mobile only in the area where the mobile is currently located,thereby eliminating useless congestion on the paging channelsin other areas of the system
There are many different conditions that could trigger an obligationfor the mobile to register
there are flags in the System Parameters Message which tellthe mobile when it must register on the current system
An Actual Registration
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An Actual Registration
16:18:27.144 Access Channel: Registration
ACK_SEQ: 7 MSG_SEQ: 1 ACK_REQ: 1 VALID_ACK: 0ACK_TYPE: 0MSID_TYPE: 3, ESN: [0x 01 99 0d fc]MFR 1, Reserved 38, Serial Number 69116,IMSI: (Class: 0, Class_0_type: 1) [0x 01 8d 31 74 29 36]00-416-575-0421AUTH_MODE: 0REG_TYPE: Timer-basedSLOT_CYCLE_INDEX: 2MOB_P_REV: 1EXT_SCM: 1SLOTTED_MODE: 1MOB_TERM: 1
REGISTRATION MESSAGE
18:26.826 [PCH] System Parameters MessagePilot_PN: 32
CONFIG_MSG_SEQ: 14 SID: 16420 NID: 0,REG_ZONE: 0 TOTAL_ZONES: 0 Zone timer length (min): 1MULT_SIDS: 0 MULT_NIDS: 0BASE_ID: 1618 BASE_CLASS: ReservedPAG_CHAN: 1 MAX_SLOT_CYCLE_INDEX: 2HOME_REG: 1 FOR_SID_REG: 1 FOR_NID_REG: 1,
POWER_UP_REG: 1 POWER_DOWN_REG: 1
PARAMETER_REG: 1 Registration period (sec): 54
Base station 00000.00 Lon., 00000.00 Lat. REG_DIST: 0SRCH_WIN_A (PN chips): 28 SRCH_WIN_N (PN chips): 100,SRCH_WIN_R (PN chips): 130 NGHBR_MAX_AGE: 2
PWR_REP_THRESH: 2 PWR_REP_FRAMES (frames): 15PWR_THRESH_ENABLE: 1 PWR_PERIOD_ENABLE: 0,PWR_REP_DELAY: 1 (4 frames) RESCAN: 0,T_ADD: -14.0dB T_DROP: -16.0dB T_COMP: 2.5dB,T_TDROP: 4sEXT_SYS_PARAMETER: 1EXT_NGHBR_LIST: 1GLOBAL_REDIRECT: 0
SYSTEM PARAMETERS MESSAGE
16:18:27.506 Paging Channel: OrderACK_SEQ: 1 MSG_SEQ: 0 ACK_REQ: 0 VALID_ACK: 1MSID_TYPE: 2 IMSI: (Class: 0, Class_0_type: 3)[0x 02 47 8d 31 74 29 36] (134) 00-416-575-0421Order type: Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The System Parameters Message tells
all mobiles when they should register.This mobile notices that it is obligated to
register, so it transmits a RegistrationMessage.
The base station confirms that themobiles registration message wasreceived. Were officially registered!
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Lets Receivean incoming Call!
CDMA Call Processing
Receiving an Incoming Call
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Receiving an Incoming Call
All idle mobiles monitor the paging channel to receive incoming
calls. When an incoming call appears, the paging channel notifies the
mobile in a General Page Message.
A mobile which has been paged sends a Page ResponseMessage on the access channel.
The system sets up a traffic channel for the call, then notifies themobile to use it with a Channel Assignment Message.
The mobile and the base station notice each others traffic channelsignals and confirm their presence by exchangingacknowledgment messages.
The base station and the mobile negotiate what type of call this willbe -- I.e., 13k voice, etc.
The mobile is told to ring and given a calling line ID to display.
When the human user presses the send button, the audio path iscompleted and the call proceeds.
An Actual Page and Page Response
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An Actual Page and Page Response
98/05/24 23:14:46.425 [ACH] Page Response MessageMSG_LENGTH = 216 bitsMSG_TYPE = Page Response MessageACK_SEQ = 1 MSG_SEQ = 2 ACK_REQ = 1VALID_ACK = 1 ACK_TYPE = 2MSID_TYPE = IMSI and ESN MSID_LEN = 9 octetsESN = 0xD30E415C IMSI_CLASS = 0IMSI_CLASS_0_TYPE = 0 RESERVED = 0IMSI_S = 6153300644AUTH_MODE = 1AUTHR = 0x307B5 RANDC = 0xC6 COUNT = 0MOB_TERM = 1 SLOT_CYCLE_INDEX = 0MOB_P_REV = 3 SCM = 106REQUEST_MODE = Either Wide Analog or CDMA OnlySERVICE_OPTION = 32768 PM = 0NAR_AN_CAP = 0 RESERVED = 0
PAGE RESPONSE MESSAGE
98/05/24 23:14:46.127 [PCH] General Page MessageMSG_LENGTH = 128 bits
MSG_TYPE = General Page MessageCONFIG_MSG_SEQ = 1 ACC_MSG_SEQ = 20CLASS_0_DONE = 1CLASS_1_DONE = 1 RESERVED = 0BROADCAST_DONE = 1 RESERVED = 0ADD_LENGTH = 0 bits ADD_PFIELD = Field OmittedPAGE_CLASS = 0 PAGE_SUBCLASS = 0MSG_SEQ = 1
IMSI_S = 6153300644SPECIAL_SERVICE = 1SERVICE_OPTION = 32768RESERVED = Field Omitted
GENERAL PAGE MESSAGE
98/05/24 23:14:46.768 [PCH] Order Message
MSG_LENGTH = 112 bitsMSG_TYPE = Order MessageACK_SEQ = 2 MSG_SEQ = 0 ACK_REQ = 0VALID_ACK = 1ADDR_TYPE = IMSI ADDR_LEN = 40 bitsIMSI_CLASS = 0 IMSI_CLASS_0_TYPE = 0 RESERVED = 0IMSI_S = 6153300644ORDER = Base Station Acknowledgement OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0
BASE STATION ACKNOWLEDGMENT
The system pages the mobile,
615-330-0644.
The base station confirms that the mobilespage response was received. Now the
mobile is waiting for channel assignment,expecting a response within 12 seconds.
The mobile responds to the page.
Channel Assignment and
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Traffic Channel Confirmation
18:14:47.598 Reverse Traffic Channel: OrderACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0ENCRYPTION: 0Mobile Station Acknowledgement Order
MOBILE STATION ACKNOWLEDGMENT
18:14:47.027 Paging Channel: Channel AssignmentACK_SEQ: 2 MSG_SEQ: 1 ACK_REQ: 0 VALID_ACK: 1MSID_TYPE: 2 IMSI: (Class: 0, Class_0_type: 0)[0x 01 f8 39 6a 15] 615-330-0644ASSIGN_MODE: Traffic Channel AssignmentADD_RECORD_LEN: 5 FREQ_INCL: 1 GRANTED_MODE: 2CODE_CHAN: 43 FRAME_OFFSET: 2ENCRYPT_MODE: Encryption disabledBAND_CLASS: 800 MHz cellular bandCDMA_FREQ: 283
CHANNEL ASSIGNMENT MESSAGE
18:14:47.581 Forward Traffic Channel: OrderACK_SEQ: 7 MSG_SEQ: 0 ACK_REQ: 1ENCRYPTION: 0 USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
Only about 400 ms. after the base stationacknowledgment order, the mobile receives
the channel assignment message.
The base station is alreadysending blank frames on
the forward channel,usingthe assigned Walsh code.
The mobile sees at least two
good blank frames in a row onthe forward channel, and
concludes this is the right trafficchannel. It sends a preambleof two blank frames of its ownon the reverse traffic channel.
The base station acknowledgesreceiving the mobiles preamble.
The mobile station acknowledges thebase stations acknowledgment.
Everybody is ready!
Service Negotiation and Mobile Alert
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Service Negotiation and Mobile Alert
18:14:47.835 Reverse Traffic Channel:Service Connect CompletionACK_SEQ: 1 MSG_SEQ: 3 ACK_REQ: 1ENCRYPTION: 0 SERV_CON_SEQ: 0
SERVICE CONNECT COMPLETE MSG.
18:14:47.760 Forward Traffic Channel: Service ConnectACK_SEQ: 0 MSG_SEQ: 1 ACK_REQ: 0 ENCRYPTION: 0
USE_TIME: 0 ACTION_TIME: 0 SERV_CON_SEQ: 0Service Configuration: supported Transmission:Forward Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsReverse Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsService option: (6) Voice (13k) (0x8000)Forward Traffic Channel: Primary TrafficReverse Traffic Channel: Primary Traffic
SERVICE CONNECT MESSAGE
Now that both sides have arrived on the
traffic channel, the base stationproposes that the requested callactually begin.
The mobile agrees andsays its ready to play.
18:14:47.961 Forward Traffic Channel:Alert With InformationACK_SEQ: 3 MSG_SEQ: 1 ACK_REQ: 1 ENCRYPTION: 0SIGNAL_TYPE = IS-54B AlertingALERT_PITCH = Medium Pitch (Standard Alert)SIGNAL = Long RESERVED = 0RECORD_TYPE = Calling Party NumberRECORD_LEN = 96 bits
NUMBER_TYPE = National NumberNUMBER_PLAN = ISDN/Telephony Numbering PlanPI = Presentation Allowed SI = Network ProvidedCHARi = 6153000124 RESERVED = 0 RESERVED = 0
ALERT WITH INFORMATION MESSAGE
The base station orders the mobile to ring, andgives it the calling partys number to display.
18:14:48.018 Reverse Traffic Channel: OrderACK_SEQ: 1 MSG_SEQ: 4 ACK_REQ: 0ENCRYPTION: 0Mobile Station Acknowledgement Order
The mobile says its ringing.
SERVICE CONNECT COMPLETE is a
major milestone in call processing. Up
until now, this was an access attempt.
Now it is officially a call.
The Human Answers! Connect Order
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The Human Answers! Connect Order
The mobile has been ringing for severalseconds. The human user finallycomes over and presses the send
button to answer the call.
Now the switch completes the audio circuit andthe two callers can talk!
18:14:54.920 Forward Traffic Channel: OrderACK_SEQ: 0 MSG_SEQ: 1 ACK_REQ: 0ENCRYPTION: 0 USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
18:14:54.758 Reverse Traffic Channel: OrderACK_SEQ: 6 MSG_SEQ: 0 ACK_REQ: 1ENCRYPTION: 0Connect Order
CONNECT ORDER
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Lets make an Outgoing Call!
CDMA Call Processing
Placing an Outgoing Call
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Placing an Outgoing Call
The mobile user dials the desired digits, and presses SEND.
Mobile transmits an Origination Message on the access channel. The system acknowledges receiving the origination by sending a
base station acknowledgement on the paging channel.
The system arranges the resources for the call and startstransmitting on the traffic channel.
The system notifies the mobile in a Channel Assignment Messageon the paging channel.
The mobile arrives on the traffic channel.
The mobile and the base station notice each others traffic channelsignals and confirm their presence by exchanging
acknowledgment messages. The base station and the mobile negotiate what type of call this will
be -- I.e., 13k voice, etc.
The audio circuit is completed and the mobile caller hears ringing.
Origination
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Origination
17:48:53.144 Access Channel: OriginationACK_SEQ: 7 MSG_SEQ: 6 ACK_REQ: 1VALID_ACK: 0 ACK_TYPE: 0 MSID_TYPE: 3
ESN: [0x 00 06 98 24] MFR 0 Reserved 1Serial Number 170020IMSI: (Class: 0, Class_0_type: 0)[0x 03 5d b8 97 c2] 972-849-5073AUTH_MODE: 0 MOB_TERM: 1SLOT_CYCLE_INDEX: 2 MOB_P_REV: 1 EXT_SCM: 1DualMode: 0 SLOTTED_MODE: 1 PowerClass: 0REQUEST_MODE: CDMA only SPECIAL_SERVICE: 1Service option: (6) Voice (13k) (0x8000) PM: 0DIGIT_MODE: 0 MORE_FIELDS: 0 NUM_FIELDS: 11Chari: 18008900829
NAR_AN_CAP: 0
ORIGINATION MESSAGE
17:48:53.487 Paging Channel: OrderACK_SEQ: 6 MSG_SEQ: 0 ACK_REQ: 0 VALID_ACK: 1
MSID_TYPE: 2IMSI: (Class: 0, Class_0_type: 0)[0x 03 5d b8 97 c2] 972-849-5073Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The mobile sends anorigination message
on the accesschannel.
The base station confirmsthat the origination message
was received.17:48:54.367 Paging Channel: Channel AssignmentACK_SEQ: 6 MSG_SEQ: 1 ACK_REQ: 0 VALID_ACK: 1
MSID_TYPE: 2IMSI: (Class: 0, Class_0_type: 0)[0x 03 5d b8 97 c2] 972-849-5073ASSIGN_MODE: Traffic Channel Assignment,ADD_RECORD_LEN: 5 FREQ_INCL: 1 GRANTED_MODE: 2CODE_CHAN: 12 FRAME_OFFSET: 0ENCRYPT_MODE: Encryption disabledBAND_CLASS: 1.8 to 2.0 GHz PCS bandCDMA_FREQ: 425
CHANNEL ASSIGNMENT MESSAGE
The base station sends aChannel Assignment
Message and the mobilegoes to the traffic channel.
Traffic Channel Confirmation
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Traffic Channel Confirmation
17:48:54.835 Reverse Traffic Channel: OrderACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0ENCRYPTION: 0Mobile Station Acknowledgement Order
MOBILE STATION ACKNOWLEDGMENT17:48:54.757 Forward Traffic Channel: OrderACK_SEQ: 7 MSG_SEQ: 0 ACK_REQ: 1 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The base station is alreadysending blank frames on
the forward channel,usingthe assigned Walsh code.
The mobile sees at least twogood blank frames in a row onthe forward channel, and
concludes this is the right trafficchannel. It sends a preambleof two blank frames of its ownon the reverse traffic channel.
The base station acknowledgesreceiving the mobiles preamble.
The mobile station acknowledges thebase stations acknowledgment.
Everybody is ready!
Service Negotiation and Connect Complete
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Service Negotiation and Connect Complete
17:48:55.137 Reverse Traffic Channel: Service Connect
Completion ACK_SEQ: 1, MSG_SEQ: 0, ACK_REQ: 1,ENCRYPTION: 0, SERV_CON_SEQ: 0
SERVICE CONNECT COMPLETE MSG.
17:48:55.098 Forward Traffic Channel: Service ConnectACK_SEQ: 7 MSG_SEQ: 1 ACK_REQ: 1 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 SERV_CON_SEQ: 0Service Configuration Supported Transmission:Forward Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsReverse Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsService option: (6) Voice (13k) (0x8000)Forward Traffic Channel: Primary TrafficReverse Traffic Channel: Primary Traffic
SERVICE CONNECT MESSAGE
Now that the traffic channel is workingin both directions, the base stationproposes that the requested call
actually begin.
The mobile agrees andsays its ready to play.
17:48:55.779 Forward Traffic Channel: OrderACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The base station agrees. SERVICE CONNECT COMPLETE is amajor milestone in call processing. Up
until now, this was an access attempt.
Now it is officially a call.
Now the switch completes the audio circuit andthe two callers can talk!
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Lets End a Call!
CDMA Call Processing
Ending A Call
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Ending A Call
A normal call continues until one of the parties hangs up. That
action sends a Release Order, normal release. The other side of the call sends a Release Order, no reason given.
If a normal release is seen, the call ended normally.
At the conclusion of the call, the mobile reacquires the system.
Searches for the best pilot on the present CDMA frequency
Reads the Sync Channel Message Monitors the Paging Channel steadily
Several different conditions can cause a call to end abnormally:
the forward link is lost at the mobile, and a fade timer acts
the reverse link is lost at the base station, and a fade timer acts
a number of forward link messages arent acknowledged, and thebase station acts to tear down the link
a number of reverse link messages arent acknowledged, and themobile station acts to tear down the link
A Beautiful End to a Normal Call
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A Beautiful End to a Normal Call
17:49:21.715 Reverse Traffic Channel: Order
ACK_SEQ: 1 MSG_SEQ: 1 ACK_REQ: 1ENCRYPTION: 0Release Order (normal release)
MOBILE RELEASE ORDER
BASE STATION ACKNOWLEDGMENT17:49:21.936 Forward Traffic Channel: OrderACK_SEQ: 1 MSG_SEQ: 2 ACK_REQ: 0 ENCRYPTION: 0,USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
At the end of a normal call, thismobile user pressed end.
The mobile left the traffic channel,
scanned to find the best pilot, and readthe Sync Channel Message.
BASE STATION RELEASE ORDER17:49:21.997 Forward Traffic Channel: OrderACK_SEQ: 1 MSG_SEQ: 3 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0Release Order (no reason given)
17:49:22.517 Sync ChannelMSG_TYPE: 1 Sync Channel MessageP_REV: 1 MIN_P_REV: 1SID: 4112 NID: 2 Pilot_PN: 183LC_STATE: 0x318fe5d84a5SYS_TIME: 0x1ae9683dcLP_SEC: 9 LTM_OFF: -10 DAYLT: 1Paging Channel Data Rate: 9600CDMA_FREQ: 425
SYNC CHANNEL MESSAGE
The base station acknowledgedreceiving the message, then senta release message of its own.
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Lets receive Notificationof a Voice Message!
CDMA Call Processing
Feature Notification
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Feature Notification
98/06/30 21:16:44.368 [PCH] Feature Notification MessageMSG_LENGTH = 144 bits
MSG_TYPE = Feature Notification MessageACK_SEQ = 0MSG_SEQ = 0ACK_REQ = 1VALID_ACK = 0
ADDR_TYPE = IMSIADDR_LEN = 56 bitsIMSI_CLASS = 0IMSI_CLASS_0_TYPE = 3RESERVED = 0MCC = 134
IMSI_11_12 = 00IMSI_S = 9055170325RELEASE = 0RECORD_TYPE = Message WaitingRECORD_LEN = 8 bitsMSG_COUNT = 1RESERVED = 0
FEATURE NOTIFICATION MESSAGE
The Feature Notification Message on
the Paging Channel tells a specificmobile it has voice messages waiting.
There are other record types to notifythe mobile of other features.
The mobile confirms it has received thenotification by sending a Mobile StationAcknowledgment Order on the access
channel.
MOBILE STATION ACKNOWLEDGMENT
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Lets do a Handoff!
CDMA Call Processing
The Detailed Rules of Soft Handoff
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Handset views pilots in sets
Active: pilots of sectors actually in use Candidates: pilots mobile requested, butnot yet set up & transmitting by system
Neighbors: pilots told to mobile by system,as nearby sectors to check
Remaining: any pilots used by system butnot already in the other sets (div. by PILOT_INC)
Handset sends Pilot Strength MeasurementMessage to the system whenever triggered by:
It notices a pilot in neighbor or remaining setexceeds T_ADD
An active set pilot drops below T_DROP forT_TDROP time
A candiDate 2011pilot exceeds an active byT_COMP
The System may set up all requested handoffs,or it may apply special manufacturer-specificscreening criteria and authorize only some
6
5
Remaining
Active
Candidate
Neighbor 20
PILOT SETSMax.Members
Reqd.ByStd.
T_COMP
T_ADD T_DROP
T_TDROP
HANDOFFPARAMETERS
Exercise: How does a pilotin one set migrate intoanother set, for all cases?Identify the trigger, and themessages involved.
The Call is Already Established. What Next?
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y
E
c/Io
All PN Offsets
0
032K
512Chips
PN
0
-20
Neighbor Set
The call is already in progress.
PN 168 is the only active signal,and also is our timing reference.
Continue checking the neighbors.
If we ever notice a neighbor with Ec/Ioabove T_ADD,
ask to use it! Send a Pilot Strength Measurement Message!
T_ADD
Rake Fingers
Reference PN
Active Pilot
10752
16832000
50014080
220
! !
Mobile Rake RX
Srch PN??? W0
F1 PN168 W61
F2 PN168 W61F3 PN168 W61
Mobile Requests the Handoff!
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q
98/05/24 23:14:02.205 [RTC]Pilot Strength Measurement MessageMSG_LENGTH = 128 bitsMSG_TYPE = Pilot Strength Measurement MessageACK_SEQ = 5 MSG_SEQ = 0 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledREF_PN = 168 Offset Index (the Reference PN)PILOT_STRENGTH = -6.0 dBKEEP = 1PILOT_PN_PHASE = 14080 chips (PN220+0chips)PILOT_STRENGTH = -12.5 dB
KEEP = 1PILOT_PN_PHASE = 32002 chips (PN500 + 2 chips)PILOT_STRENGTH = -11.0 dBKEEP = 1RESERVED = 0
PILOT STRENGTH MEASUREMENT MESSAGE
98/05/24 23:14:02.386 [FTC] Order MessageMSG_LENGTH = 64 bitsMSG_TYPE = Order Message
ACK_SEQ = 0 MSG_SEQ = 0 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledUSE_TIME = 0 ACTION_TIME = 0ORDER = Base Station Acknowledgement OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field OmittedRESERVED = 0
BASE STATION ACKNOWLEDGMENT
Just prior to this message, this particularmobile already was in handoff with PN 168and 220.This pilot strength measurement messagereports PN 500 has increased above
T_Add, and the mobile wants to use it too.
The base station acknowledges receiving
the Pilot Strength Measurement Message.
System Authorizes the Handoff!
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y
98/05/24 23:14:02.926 [FTC] Extended Handoff Direction MessageMSG_LENGTH = 136 bits
MSG_TYPE = Extended Handoff Direction MessageACK_SEQ = 0 MSG_SEQ = 6 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledUSE_TIME = 0 ACTION_TIME = 0 HDM_SEQ = 0SEARCH_INCLUDED = 1SRCH_WIN_A = 40 PN chipsT_ADD = -13.0 dB T_DROP = -15.0 dB T_COMP = 2.5 dBT_TDROP = 4 secHARD_INCLUDED = 0FRAME_OFFSET = Field OmittedPRIVATE_LCM = Field OmittedRESET_L2 = Field OmittedRESET_FPC = Field OmittedRESERVED = Field Omitted
ENCRYPT_MODE = Field OmittedRESERVED = Field OmittedNOM_PWR = Field OmittedNUM_PREAMBLE = Field OmittedBAND_CLASS = Field OmittedCDMA_FREQ = Field OmittedADD_LENGTH = 0PILOT_PN = 168 PWR_COMB_IND = 0 CODE_CHAN = 61PILOT_PN = 220 PWR_COMB_IND = 1 CODE_CHAN = 20PILOT_PN = 500 PWR_COMB_IND = 0 CODE_CHAN = 50RESERVED = 0
HANDOFF DIRECTION MESSAGE
The base station sends a HandofDirection Message authorizing themobile to begin soft handoff with allthree requested PNs. The pre-existinglink on PN 168 will continue to useWalsh code 61, the new link on PN220will use Walsh Code 20, and the newlink on PN500 will use Walsh code 50.
The mobile acknowledges it has receivedthe Handoff Direction Message.
98/05/24 23:14:02.945 [RTC] Order Message
MSG_LENGTH = 56 bits MSG_TYPE = Order MessageACK_SEQ = 6 MSG_SEQ = 6 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledORDER = Mobile Station Acknowledgement Order
ADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0
MOBILE STATION ACKNOWLEDGMENT
Mobile Implements the Handoff!
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p
The mobile searcher quickly re-checksall three PNs. It still hears their pilots!
The mobile sends a Handoff CompletionMessage, confirming it still wants to go
ahead with the handoff.
98/05/24 23:14:03.085 [FTC] Forward Traffic Channel: OrderACK_SEQ: 0 MSG_SEQ: 1 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
98/05/24 23:14:02.985 [RTC] Handoff Completion Message
MSG_LENGTH = 72 bitsMSG_TYPE = Handoff Completion MessageACK_SEQ = 6 MSG_SEQ = 1 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledLAST_HDM_SEQ = 0PILOT_PN = 168 Offset IndexPILOT_PN = 220 Offset IndexPILOT_PN = 500 Offset IndexRESERVED = 0
HANDOFF COMPLETION MESSAGE
The base station confirms it hasreceived the mobiles HandoffCompletion message, and willcontinue with all of the linksactive.
Neighbor List Updated, Handoff is Complete!
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g p , p
98/05/24 23:14:03.245 [RTC] Order MessageMSG_LENGTH = 56 bits MSG_TYPE = Order MessageACK_SEQ = 7 MSG_SEQ = 7 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledORDER = Mobile Station Acknowledgement OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field OmittedRESERVED = 0
MOBILE STATION ACKNOWLEDGMENT
98/05/24 23:14:03.166 [FTC] Neighbor List UpDate 2011MessageMSG_LENGTH = 192 bits
MSG_TYPE = Neighbor List UpDate 2011MessageACK_SEQ = 1 MSG_SEQ = 7 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledPILOT_INC = 4 Offset IndexNGHBR_PN = 164 Offset IndexNGHBR_PN = 68 Offset IndexNGHBR_PN = 52 Offset IndexNGHBR_PN = 176 Offset IndexNGHBR_PN = 304 Offset IndexNGHBR_PN = 136 Offset IndexNGHBR_PN = 112 Offset Index
NGHBR_PN = 372 Offset IndexNGHBR_PN = 36 Offset IndexNGHBR_PN = 8 Offset IndexNGHBR_PN = 384 Offset IndexNGHBR_PN = 216 Offset IndexNGHBR_PN = 328 Offset IndexNGHBR_PN = 332 Offset IndexNGHBR_PN = 400 Offset IndexNGHBR_PN = 96 Offset IndexRESERVED = 0
NEIGHBOR LIST UPDate 2011MESSAGE
In response to the mobiles HandoffCompletion Message, the base stationassembles a new composite neighborlist including all the neighbors of each ofthe three active pilots.This is necessary since the mobile
could be traveling toward any one ofthese pilots and may need to requestsoft handoff with any of them soon.
The mobile confirms receiving theNeighbor List UpDate 2011Message. It
is already checking the neighbor list andwill do so continuously from now on.
The handoff is fully established.
Handoff Now In Effect, keep checking Pilots!
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Ec/Io
All PN Offsets
0
032K
512Chips
PN
0
-20
Neighbor Set
Continue checking each ACTIVE pilot. If any are less than T_DROP and remain
so for T_TDROP time, send Pilot Strength Measurement Message, DROP IT!!
Continue checking each NEIGHBOR pilot. If any ever rises above T_ADD, send
PSMM, ADD IT! Keep watching CANDIDATES vs ACTIVES using T_COMP, too.
T_ADD
Rake Fingers
Reference PN
Active Set
10752
16832000
50014080
220
T_DROP
Mobile Rake RX
Srch PN??? W0
F1 PN168 W61
F2 PN500 W50F3 PN220 W20
The Complete Picture of Handoff & Pilot Sets
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T_ADD
Ec/Io
All PN Offsets
00
32K512
ChipsPN
0
-20
Neighbor Set
SRCH_WIN_N
Active Set
CandiDate 2011SetT_DROP
SRCH_WIN_A
Remaining Set
T_ADDSRCH_WIN_R
SRCH_WIN_A
T_DROP
Rake Fingers
Reference PN
Pilots of sectorsnow used forcommunication
Pilots requestedby mobile but notset up by system
Pilots suggestedby system for
more checking
All other pilots divisible by PILOT_INC but notpresently in Active, Candidate, or Neighbor sets
Mobile Rake RX
Srch PN??? W0
F1 PN168 W61F2 PN500 W50
F3 PN220 W20
Timing of Pilot Searchers Measurement Process
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The searcher checks pilots in nestedloops, much like meshed gears.Actives and candidatesoccupy the fastest-spinning wheel.Neighbors arenext, advancingone pilot for each
Act+Cand. revolution.Remaining is slowest,advancing one pilot eachtime the Neighbors revolve.
CURRENT PILOT SET CONTENTSA A A
C
N N N N N N N N N N N N
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R R R R R R R R R
R R R R
3
112112
PILOT SEARCHER VIEWED IN SEQUENCE: Typical Elapsed Time = 4 seconds
A A A C N
R
A A A C A A A C A A A C A A A C A A A C A A A CN N N N N N
A A A C N A A A C A A A C A A A C A A A C A A A C A A A CN N N N N
A A A CN A A A C A A A C A A A C A A A C A A A C A A A CN N N N N N
N A A A C A A A C A A A CN N N R A A A C N A A A C A A A C A A AN N
C A A A C A A A CN N N
R
A A A C N A A A C A A A C A A AN N C A A AN
C A A A CN N Only 3 of 112 remaining set pi lots have been c hecked thu s far!
A
N
R
R
R
R
R
R
R
NN
N
N
NN
N N
A
A
Troubleshooting Call Events:S
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Watch Messaging, Mobile State
Your current capabilities
Earlier in this course we reviewed handset call processingstates
You have just seen the entire vocabulary of messagesordinarily used in call processing
Now youre equipped to do serious troubleshooting of CDMA
calls! Auditing Call Processing Problems using messages
Watch the messages from birth (origination) to death (release)
is the order proper? are there inappropriate responses?
are any messages repeated? why? which link is bad?
are any messages missed or not acknowledged?
are contents and included parameter values reasonable?
is the timing appropriate -- delays not too long?
track the state in which the mobile and system should be
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Course 134
Handoff Perspective
Overall Handoff Perspective
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Soft & Softer Handoffs are preferred, but not always possible
a handset can receive BTS/sectors simultaneously only on onefrequency
all involved BTS/sectors must connect to a networked BSCs.Some manufacturers do not presently support this, and so areunable to do soft-handoff at boundaries between BSCs.
frame timingmust be same on all BTS/sectors
If any of the above are not possible, handoff still can occur but canonly be hard break-make protocol like AMPS/TDMA/GSM
intersystem handoff: hard
change-of-frequency handoff: hard CDMA-to-AMPS handoff: hard, no handback
auxiliary trigger mechanisms available (RTD), Ec/Io
Global Service Redirection Messages on outlooking sectors.
Which is better - 3-way or 6-way Soft Handoff?
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3 Way or 6 Way?
All handsets are capable of up to 6-way soft handoff
Nortel & Qualcomm networks allow up to 6-way soft-handoff
Lucent and Motorola networks allow only up to 3 way softhandoff
bug or feature?Advantage of 6-way: mobile does not depend on speedy
system reaction to handoff requests; this gives somewhatimproved dropped call rates in areas with extensive RFoverlap
Disadvantage: additional channel elements are used
Optional Network-Specific Handoff Features
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Ec/Io Handoff CandiDate 2011Screening
all networks rank the pilots reported by the mobiles, and incases where more candidates are proposed than the networkcan support in soft handoff, the soft handoff is set up using thebest N pilots
Some networks also screen candidates and apply a more
conservative theory when authorizing handoffs some networks use T_Comp as a secondary parameter to
implement hysteresis and prevent hyperactive handoffs
Some networks are experimenting with algorithms for dynamic,adaptive assignment of T_Add, T_Drop, and T_Comp
Nortel Handoff & Channel Allocation Features
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Inter-System Soft Handoff (ISSHO)
Soft handoff across SBS and MTX boundaries Multi-Carrier Traffic Allocation (MCTA)
Intelligent carrier selection during call setup
Soft Handoff Reduction Algorithm (SHORA)
Eliminating unneeded excessive soft handoff to improve capacity
Multi_Pilot Hard HandOff (MPHHO) Round-trip delay triggers, Pilot Beacon techniques
Enhanced Hard HandOff (EHHO)
Call quality triggers hard handoff when necessary
Multi-Mode Hard HandOff (MMHHO)
Sending capable CDMA mobiles between band classes or to analog
For more detail and latest improvements to all these features andalgorithms, take the Nort