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Course 302
CDMA Performance Optimization
with Grayson CDMA Inspector32
CDMA Performance Optimization
with Grayson CDMA Inspector32
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Outline: Using Surveyor for Optimization
Introduction: Review of CDMA Principles (optional based onportions needed)
CDMA Air Interface Review
CDMA Spread Spectrum Basics
CDMA Signal RF Characteristics
CDMA Spreading Sequences and Code Channels
Forward LinkReverse Link
Call Processing from perspective of Subscriber Handset
Anatomy of a HandsetRF section, digital section, correlators
Operation of the Pilot Searcher
Subscriber Handset Operation, wakeup thru end of call
Messaging Overview
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Outline: Using Surveyor for Optimization
CDMA Handoff
Pilot Sets: Relationships, number of members, promotion& demotion
Handoff Parameters Handoff Messaging
RF Implications of Handoff Situations
CDMA System Network Architecture and Hardware BasicElements
CDMA Datagathering Introduction
System-side resources, principles, tools: (overview)
Subscriber-side resources, principles, and techniques Handset maintenance mode
Surveyor32 Real-Time and Replay
Analyzer - its role and purpose
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Outline: Using Surveyor for Optimization
Interpreting Real-Time Drive-Tool Displays from Surveyor32
Parameters and values
RF significance of observed values (Ec/Io, TX Gain, TX PO,
RX Level) Seeing the situation through the eyes of the handset
Real-World CDMA Problems and Solutions
Live Examples using Datafiles collected by the class
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Course 302
Whats Different about CDMA?
Basic Principles Review
Whats Different about CDMA?
Basic Principles Review
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Other Technologies:Recovering the Signal / Avoiding Interference
In conventional radio technologies, thedesired signal must be strong enough tooverride any interference
AMPS, TDMA and GSM depend onphysical distance separation to keepinterference at low levels
Co-channel users are kept at a safedistance 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
3
6
1
1
1
1
1
1
1
AMPS-TDMA-GSM
Figure of Merit: C/I(carrier/interference ratio)AMPS: +17 dB
TDMA: +14 to 17 dBGSM: +7 to 9 dB.
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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, the signals are
hopelessly entangled both in time andfrequency
CDMA operates by using CODING todiscriminate between users
In CDMA systems, the interference comesmainly from other nearby CDMA users
Each users signal is like a small voice in aroaring crowd -- but built using a unique
code that allows the signal to be uniquelydecoded and recovered by the recipient
CDMA
Figure of Merit: C/I(carrier/interference ratio)
AMPS: +17 dBTDMA: +14 to +17 dB
GSM: +7 to 9 dB.CDMA: -10 to -17 dB.CDMA: Eb/No ~+6 dB.
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CDMA Uses Code Channels
A CDMA signal uses many chips to convey justone bit of information
Each user has a unique chip pattern, in effect acode channel
To recover a bit, integrate a large number of chipsinterpreted by the users known code pattern
Other users code patterns appear random andadd up to zero in a random self-canceling fashion,thus they dont disturb the bit decoding decisionbeing made with the proper code pattern
The process of going from Symbols into Chips iscalled spreading, since the slow, narrow-bandwidth information is spread so that itoccupies a much larger bandwidth
Building aBuilding aCDMA SignalCDMA Signal
Bitsfrom Users Vocoder
Symbols
Chips
Forward ErrorCorrection
Coding and
Spreading
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Spreading, from a Time-Domain point of view
At Originating Site:
Input A: Users Data @19,200 bits/second
Input B: Walsh Code #23@ 1.2288 Mcps
Output: Spreadspectrum signal
At Destination Site:
Input A: Receivedspread 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: a Frequency-Domain Point of View
Traditional wireless technologies try tosqueeze one signal into a minimumamount of bandwidth, so there can bemany one-user channels
the data rate of the information
dictates how wide a bandwidth thesignal requires; its narrow
CDMA mixes slow information with a fastspreading sequence
this makes a CDMA signal with much
wider bandwidth than the informationalone would require
the extra bandwidth gives a paybackof processing gain which extendscoverage range and improves theradio link performance for users
Multiple users can occupy one CDMAsignal, if each users information is mixedwith a unique, distinct personal spreadingsequence, and then all added together.
Decode the combined signal using
one users spreading sequence, andthat one users signal is recovered
Spread Spectrum Payoff:Processing Gain
Multiple users with diferent codes
Spread SpectrumTRADITIONAL COMMUNICATIONS SYSTEM
SlowInformation
Sent
TX
SlowInformationRecovered
RX
NarrowbandSignal
SPREAD-SPECTRUM SYSTEM
Fast
SpreadingSequence
SlowInformation
Sent
TX
SlowInformationRecovered
RX
Fast
SpreadingSequence
Wideband
Signal
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CDMA: is it really magic, or just a card trick?
if 1 =if 0 =
1
Analog
SummingUsers
QPSK RF
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 of
CDMA signal generation and recovery.The actual coding process used in IS-95 CDMA includesa few additional layers, as well see in following slides.
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The Concept of Orthogonality
Each users signal must bebuilt using a unique
spreading sequence, if we areto recover it individually
if users spreadingsequences arent unique,
all users signals will behopelessly jumbledtogether andunrecoverable
This uniqueness is calledOrthogonality
The spreading sequences weuse in CDMA are orthogonal
Comparing Signals:Are they Orthogonal?
Two signals are orthogonal if theircorresponding bits match in half thepositions, and dont match in half thepositionsOne way to check for orthogonality is
to add the two signals in binary form(modulo 2).If the signals are orthogonal, the sumwill contain exactly as many ones aszeroes..
0 1 1 0 1 1 1 0
0 0 1 0 1 1 0 0
0 1 0 0 0 0 1 0=
+
Signal A
Signal B
Binary Sum
Not these two signals!
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Spreading: Whatever we encode, we can decode
Sender combines data with a fast spreading sequence, transmits
spread data stream Receiver intercepts the stream, uses same spreading sequence
to extract original data
If this basic idea makes sense, youre ready to understand the fullprocess used in commercial CDMA
ORIGINATING SITE DESTINATION
SpreadingSequence
SpreadingSequence
InputData RecoveredData
Spread Data Stream
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Shipping and Receiving via CDMA
Whether in package shipping and receiving, or in CDMA signals,
packaging methods are extremely important! Cargo is placed inside nested containers. Each container has
some special purpose -- for example, the disk is readable by aPC, the mailer keeps the disk from getting bent or damaged, and
the shipping envelope can be addressed to the final destination The shipper packs in a certain order, and the recipient unpacks
in the reverse order
For CDMA signals, the containers for our shipment are three
different kinds of spreading codes, and each one is used for aspecific purpose
Fed
Ex
Data Mailer
Fed
Ex
DataMailer
Shipping Receiving
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CDMAs Three Nested Spreading Sequences
CDMA signals are built up using three different types of spreadingsequences -- this makes each signal unique and very rugged/robust
These sequences are easy to generate, in a base station and in a handset
Using these sequences, Whatever we encode, we can decode
Next step is to meet these sequences, see their special properties
what are their functions on the forward link (base station to mobile) ?
what are their functions on the reverse link (mobile to base station) ?
Dont worry about each sequence exact purpose yet; these are different onthe forward and reverse links; well see their jobs after the introductions
Spreading
SequenceA
Spreading
SequenceB
Spreading
SequenceC
Spreading
SequenceC
Spreading
SequenceB
Spreading
SequenceA
InputData
X
RecoveredData
X
X+A X+A+B X+A+B+C X+A+B X+A
Spread-Spectrum Chip StreamsORIGINATING SITE DESTINATION
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Sneak Preview of the other CDMA Sequences
The other two CDMA sequencesare generated in shift registers
An ordinary shift register is no fun,
sequence length = register length
A Tapped shift register generatesa wild, self-mutating sequence2N-1 chips 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 ~1%
A Tapped, Summing Shift Register
Sequence repeats every 2N
-1 chips,where N is number of cells in register
An Ordinary Shift Register
Sequence repeats every Nchips,where N is number of cells in register
A Special Characteristic of SequencesGenerated in Tapped Shift Registers
Compared In-Step: Matches Itself
Complete Correlation: All 0sSum:
Self, in sync:
Sequence:
Compared Shifted: Little Correlation
Practically Orthogonal: Half 1s, Half 0sSum:
Self, Shifted:
Sequence:
M t th CDMA S di S
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Meet another CDMA Spreading Sequence:The PN Short Code
The PN Short Code consists of twoPN Sequences, I (in-phase) and Q(quadrature), each 32,768 chips long
Theyre generated in similar butdifferently-tapped 15-bit-long shiftregisters
I&Q always used simultaneously,modulating the two phase axesof a QPSK RF modulator
The PN Short Code
IQ
32,768 chips long
26-2/3 ms.(75 repetitions in 2 sec.)
CDMA QPSK Phase ModulatorUsing I and Q PN Sequences
I-sequence
Q-sequence
cos t
sin t
chip
input
QPSK-modulatedRF
Output
*
* In BTS, I and Q are used in-phase.In handset, Q is delayed 1/2 chip toavoid zero-amplitude crossings which
would require a linear power amplifier
Acronym: PN = Pseudorandom Noise
Meet another CDMA Spreading Sequence:
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Meet another CDMA Spreading Sequence:The PN Long Code
Generated in a 42-bit register, the PN Long code is more than 40 dayslong (~4x1013 chips) -- too big to store in ROM in a handset, so itsgenerated chip-by-chip using the scheme shown above
Each handset codes its signal with the PN Long Code, but at a uniqueoffset 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 differentPN long code offsets will appear practically orthogonal
Long CodeState Register(@ 1.2288 MCPS)
PublicLong Code Mask
(STATIC)
User Long CodeSequence
(@1.2288 MCPS)
1 1 0 0 0 1 1 0 0 0 Ph o n e s ESN , Pe rmu t e d+
=SUMModulo-2 Addition
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Putting it All Together: the CDMA Channels
All three spreading codes are used on both the forward and reverse links Forward Channel: Each Sector has a unique PN Short Code offset, each userin that sector has a personal Walsh Code
long code is used incidentally for scrambling Reverse Channel: Each phone has a unique PN Long Code offset, different
from every other phone in the world Incidentally, Walsh Codes used as symbols, short code for modulation
BTSPN LONG CODEat users offset
FORWARD CHANNEL
REVERSE CHANNEL
All WALSH CODES
used as tokensfor user bits,makes signalvery robust
scrambled + WALSH CODE
scrambled + WALSH CODE
scrambled + WALSH CODE
scrambled + WALSH CODE
PN SHORT CODE
at unique PN offset
of BTS sector
SHORT PN:
used at offset 0,gives OQPSKmodulation
by Long Code
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How a BTS Builds the Forward Code Channels
BSC orAccessManager
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 CodePN Offset 246
Trans-mitter,
Sector X
Switch
more
a Channel Element
A Forward Channelis identified by:
its CDMA RFcarrier Frequency
the unique Short
Code PN Offset ofthe sector
the unique WalshCode of the user
FECWalsh #23
Q
I
x
x
+
cos t
sin t
I Q
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Functions of the CDMA Forward Channels
PILOT: WALSH CODE 0 The Pilot is a structural beacon which
does not contain a character stream. It is atiming source used in system acquisitionand as a measurement device during
handoffs SYNC: WALSH CODE 32
This carries a data stream of systemidentification 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 20
Sync 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(Access
Manager)
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 carrier Frequency
the unique Long Code PN Offsetof the individual handset
Channel Element
Channel Element
Channel Element
Channel Element
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
more
Long
Codeoffset LongCodeoffset Long
Codeoffset
Long
Codeoffset
LongCode
offset
LongCodeoffset
F ti f th CDMA R Ch l
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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 defined by 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 yet in acall to transmit registration requests, call setuprequests, page responses, order responses, and othersignaling information
an access channel is defined by a public longcode mask specific to the BTS sector
Access channels are paired with PagingChannels. There can be up to 32 accesschannels per paging channel
REG
1-800
242
4444
BTS
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Basic CDMA Network Architecture
Access Manageror (C)BSC
Switch BTS
Ch. Card
Vocoders
Selectors
CDSU
CDSU
DTCs
TxcvrB
RFFEB
GPS
PSTN
DISCO 1
DS0 in T1Packets Chips
RFChannelElementVocoder
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Variable Rate Vocoding & Multiplexing
Vocoders compress speech, reduce bitrate
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 secondarydata may be mixed in CDMA frames
The protocols governing the mixture arethe Multiplex Options; 1 = 8K, 2 = 13K
The content of the primary traffic bits aredetermined by Service Options which themobile and system negotiate
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
ForwardRF
BSC BTS (1 sector)
Sync
Pilot
Paging
more
Short PN
Trans-mitter,
Sector X
I QUser 1User 2
User 3Vocoder/Selector
Help!
R P C l
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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
Wh t I H d t?
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Whats In a Handset?
ReceiverRF SectionIF, Detector
TransmitterRF Section
Vocoder
DigitalRake Receiver
Traffic Correlator
PN xxx Walsh xx
Traffic CorrelatorPN xxx Walsh xxTraffic Correlator
PN xxx Walsh xx
Pilot Searcher
PN xxx Walsh 0
ViterbiDecoder
CPUDuplexer
TransmitterDigital Section
Long Code Gen.
Open
L
oop
Transmit Gain Adjust
Messages
Messages
Audio
Audio
Packets
Symbols
SymbolsChips
RF
RF
AGC
Th R k R i
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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
RF
PN Walsh
PN Walsh
PN Walsh
SearcherPN W=0
Voice,Data,
Messages
Pilot Ec/Io
BTS
BTS
CDMA S ft H d ff M h i
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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
Searcher
PN W=0
Voice,Data,
Messages
Pilot Ec
/Io
BTS
BSCSwitch
BTS
Sel.
Softer Handoff
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Softer Handoff
Each BTS sector has unique PN offset & pilot
Handset will ask for whatever pilots it wants
If multiple sectors of one BTS simultaneously serve a handset, this iscalled Softer Handoff
Handset is unaware, but softer handoff occurs in BTS in a singlechannel element
Handset can even use combination soft-softer handoff on multipleBTS & sectors
Handset Rake Receiver
RF
PN Walsh
PN Walsh
PN Walsh
Searcher
PN W=0
Voice,Data,
Messages
Pilot Ec
/Io
BTS
BSCSwitch
Sel.
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Course 302
CDMA Messaging and Call FlowCDMA Messaging and Call Flow
Messaging as an Investigative Resource:
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Messaging as an Investigative Resource:Why did a Flight Crash? Why did a Call Drop?
Layer-3 Messaging between systemand phone during a call is much likein-flight voice messaging betweenair traffic controllers and pilots.
When a call drops or a flight goes
down, intense investigation of themessaging will often identify thecause of the problem.
The Cockpit Voice Recorder givesextremely valuable information. The
CDMA equivalent is a log file fromdrive-test equipment. It can answer:
What was the call state at thetime of the crash? (handoffs,primary PN, mobile parameters)
Was messaging reliable? Were there any pending
messages not acknowledged orrequests not yet implementedon either side?
Was either link under stress?
CDMA Messaging is much likeAir Traffic Control messaging
BTS
Sources of CDMA Data and Tools for Processing
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g
CDMA optimization data flows from three places: Switch, CDMA peripherals and base stations, and the Handset
Various software and hardware tools are available for collectionand analysis of each of these streams of data
Data contains messages and various indicators of RF performance
Access Mgr./BSC-BSMSwitch BTS
CDSU DISCO
Ch. Card ACC
TFU1
GPSR
CDSU
CDSU
DISCO 1
DISCO 2
SBSVocoders
Selectors
CDSU
CDSU
CDSU
CDSU
CDSU
CDSU
CMSLM
LPP LPPENET
DTCs
DMS-BUS
Txcvr A
Txcvr B
Txcvr C
RFFE A
RFFE B
RFFE C
TFU1
GPSR
IOC
BSM
Data AnalysisPost-Processing
Tools
IS-95/J Std 8 Messages
IS-95/J Std 8Messages
NOIS Messages
QC-Specific Messages
Switch OMs,
pegs, logs
Mobile DataPost-Processing
Tools
Mobile DataCapture ToolsSelector
Logs
NMIS Messages
HandsetMessages
ExternalAnalysis
Tools
PC-based
PC-based
Unix-based,PC-basedVarious
CDMA NETWORK EQUIPMENT HANDSET
Structure of CDMA Messages
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Structure of CDMA Messages
CDMA messages on both forwardand reverse links are normally sentvia dim-and-burst
Messages include many fields of
binary data The first byte of each message
identifies message type to allow therecipient to parse the contents
To ensure no messages aremissed, all CDMA messages bearserial numbers and importantmessages contain a bit requestingacknowledgment
Messages not promptlyacknowledged are retransmittedseveral times, after which thesender may release the call
Surveyor parses all messages forreview and analysis
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
Messages In Acquisition and Idle States
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g q
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 Msg
Service Redirection Msg
General Page Msg
Null Msg Data Burst Msg
Access Channel
Registration Msg
Order Msg Mobile Station Acknowldgment
Long Code Transition Request SSD Update Confirmation
many others..
Origination Msg
Page Response Msg
Authentication ChallengeResponse Msg
Status Response Msg
TMSI AssignmentCompletion Message
Data Burst Msg
BTS
Messages During a Call: Conversation State
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Messages During a Call: Conversation State
Reverse Traffic Channel
Order Message
Mobile Sta. Acknowledgment
Long Code TransitionRequest
SSD Update Confirmation
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 Acknowledgment
Base Station ChallengeConfirmation
Message Encryption Mode
AuthenticationChallenge Msg
Alert WithInformation Msg
Data Burst Msg
Analog HandoffDirection Msg
In-Traffic SystemParameters Msg
Neighbor ListUpdate Msg
Send Burst DTMF Msg
Power ControlParameters Msg.
Retrieve Parameters Msg
Set Parameters Msg
SSD Update Msg
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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Adventures in Call Processing5 Minutes in the Life of a CDMA HandsetAdventures in Call Processing
5 Minutes in the Life of a CDMA Handset
30Seconds
(thatsall
wevego
ttimeto
doinone
day!)
Our Call Processing Adventures
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Our Call Processing Adventures
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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Lets Acquire the System!Lets Acquire the System!
CDMA Call Processing
Find a Frequency with a CDMA RF Signal
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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 5etc.
Forward Link Frequencies(Base Station Transmit)
A D B E F Cunlic.
data
unlic.
voiceA 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)
Find Strongest Pilot, Read Sync Channel
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g , y
Rake Fingers
Reference PN
Active Pilot
Ec/Io
0
032K
512Chips
PN
1. Pilot SearcherScans the Entire Range of PNs
All PN Offsets
0
-20
98/05/24 23:14:09.817 [SCH]
Sync Channel Message
MSG_LENGTH = 208 bitsMSG_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 strongest
available PN, decode Walsh 32,
and read Sync Channel Message
SYNC CHANNEL MESSAGE
Handset Rake Receiver
RF x
LOSrch PN??? W0
F1 PN168 W32
F2 PN168 W32
F3 PN168 W32
The Configuration Messages
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g g
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
Go to Paging Channel, Get Configured
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g g , g
Rake Fingers
Reference PN
Active Pilot
Ec/Io
0
032K
512Chips
PN
All PN Offsets0
-20
Keep Rake finger(s) on strongest
available 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
LOSrch PN??? W0
F1 PN168 W01
F2 PN168 W01
F3 PN168 W01
Two Very Important Configuration Messages
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y p g g
98/05/24 23:14:10.427 [PCH]MSG_LENGTH = 184 bitsMSG_TYPE = Access Parameters MessagePILOT_PN = 168 Offset Index
ACC_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 MaximumPAM_SZ = 3 Access Channel FramesPersist Val for Acc Overload Classes 0-9 = 0Persist Val for Acc Overload Class 10 = 0
Persist 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 MESSAGE 98/05/24 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 = 0HOME_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 = 1
RESERVED = 0GLOBAL_REDIRECT = 0
SYSTEM PARAMETERS MESSAGE
Four Additional Configuration Messages
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98/05/24 23:14:10.946 [PCH]Extended System Parameters MessageMSG_LENGTH = 104 bits
MSG_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 = 0
RESERVED = 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 analogsystem
Attempt 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 Message
MSG_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 Index
NGHBR_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 Message
PILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0CDMA_FREQ = 283RESERVED = Field Omitted
CDMA CHANNEL LIST MESSAGE
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Lets do anIdle Mode Handoff!
Lets do an
Idle Mode Handoff!
CDMA Call Processing
Idle Mode Handoff
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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, not
synchronous -- 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 is
required, it re-registers on the new sector
Idle Mode on the Paging Channel:Meet the Neighbors, track the Strongest Pilot
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Meet the Neighbors, track the Strongest Pilot
Ec/Io
All PN Offsets
0
032K
512Chips
PN
0
-20
Neighbor Set
The phones pilot searcher constantly checksthe 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 idle 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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A sectors Paging Channel announces 1(typ) to 32 (max) Access Channels: PNLong 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 not
yet under BTS closed-loop power control! Phones access the BTS by probing at
power levels determined by receive power
and an open loop formula If probe not acknowledged by BTS
within 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 all
related 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 TFC
RV TFC
FW TFC
FW TFC
A Successful Access Attempt
a Probe Sequencean Access Attempt
Success!
an Access Probe
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Lets Register!Lets Register!
CDMA Call Processing
Registration
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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 of
the mobiles current location, so that incoming calls can bedelivered
registration also allows the system to intelligently page themobile 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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16:18:27.144 Access Channel: RegistrationACK_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]00-416-575-0421
AUTH_MODE: 0REG_TYPE: Timer-basedSLOT_CYCLE_INDEX: 2MOB_P_REV: 1EXT_SCM: 1
SLOTTED_MODE: 1MOB_TERM: 1
REGISTRATION MESSAGE
18:26.826 [PCH] System Parameters MessagePilot_PN: 32CONFIG_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: 2PWR_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] (302) 00-416-575-0421Order type: Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The System Parameters Message tellsall mobiles when they should register.
This mobile notices that it is obligated toregister, so it transmits a Registration
Message.
The base station confirms that themobiles registration message was
received. Were officially registered!
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Lets Receivean incoming Call!
Lets Receive
an incoming Call!
CDMA Call Processing
Receiving an Incoming Call
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All idle mobiles monitor the paging channel to receive incomingcalls.
When an incoming call appears, the paging channel notifies themobile 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 is
completed and the call proceeds.
An Actual Page and Page Response
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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 = 0
IMSI_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 bitsMSG_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 = 6153300644
SPECIAL_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 Order
ADD_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 andTraffic Channel Confirmation
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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: 2
CODE_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 onthe forward channel,usingthe assigned Walsh code.
The mobile sees at least twogood blank frames in a row on
the 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 acknowledges
receiving the mobiles preamble.
The mobile station acknowledges the
base stations acknowledgment.Everybody is ready!
Service Negotiation and Mobile Alert
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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: 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 Traffic
Reverse Traffic Channel: Primary Traffic
SERVICE CONNECT MESSAGE
Now that both sides have arrived on thetraffic channel, the base stationproposes that the requested call
actually begin.
The mobile agrees andsays its ready to play.18:14:47.961 Forward Traffic Channel:Alert With Information
ACK_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, and
gives 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 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!Lets make an Outgoing Call!
CDMA Call Processing
Placing an Outgoing Call
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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 abase 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 Message
on 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.
OriginationORIGINATION MESSAGE
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17:48:53.144 Access Channel: Origination
ACK_SEQ: 7 MSG_SEQ: 6 ACK_REQ: 1VALID_ACK: 0 ACK_TYPE: 0 MSID_TYPE: 3ESN: [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: 1
DualMode: 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: 18008900829NAR_AN_CAP: 0
ORIGINATION MESSAGE
17:48:53.487 Paging Channel: OrderACK_SEQ: 6 MSG_SEQ: 0 ACK_REQ: 0 VALID_ACK: 1MSID_TYPE: 2IMSI: (Class: 0, Class_0_type: 0)[0x 03 5d b8 97 c2] 972-849-5073
Base Station Acknowledgement Order
BASE STATION ACKNOWLEDGMENT
The mobile sends an
origination messageon the access
channel.
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 band
CDMA_FREQ: 425
CHANNEL ASSIGNMENT MESSAGE
The base station sends aChannel Assignment
Message and the mobile
goes to the traffic channel.
Traffic Channel Confirmation
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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: Order
ACK_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 on
the forward channel, andconcludes this is the right traffic
channel. 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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17:48:55.137 Reverse Traffic Channel: Service ConnectCompletion 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 bps
Service option: (6) Voice (13k) (0x8000)Forward Traffic Channel: Primary TrafficReverse Traffic Channel: Primary Traffic
SERVICE CONNECT MESSAGENow that the traffic channel is working
in 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 and
the two callers can talk!
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Lets End a Call!Lets End a Call!
CDMA Call Processing
Ending A Call
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A normal call continues until one of the parties hangs up. Thataction 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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17:49:21.715 Reverse Traffic Channel: OrderACK_SEQ: 1 MSG_SEQ: 1 ACK_REQ: 1ENCRYPTION: 0Release Order (normal release)
MOBILE RELEASE ORDER
BASE STATION ACKNOWLEDGMENT
17:49:21.936 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, this
mobile user pressed end.
The mobile left the traffic channel,
scanned to find the best pilot, and readthe Sync Channel Message.
BASE STATION RELEASE ORDER
17:49:21.997 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: 9600
CDMA_FREQ: 425
SYNC CHANNEL MESSAGE
The base station acknowledgedreceiving the message, then sent
a release message of its own.
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Lets receive Notification
of a Voice Message!
Lets receive Notification
of a Voice Message!
CDMA Call Processing
Feature Notification
FEATURE NOTIFICATION MESSAGE
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98/06/30 21:16:44.368 [PCH] Feature Notification MessageMSG_LENGTH = 144 bitsMSG_TYPE = Feature Notification MessageACK_SEQ = 0MSG_SEQ = 0ACK_REQ = 1VALID_ACK = 0ADDR_TYPE = IMSI
ADDR_LEN = 56 bitsIMSI_CLASS = 0IMSI_CLASS_0_TYPE = 3RESERVED = 0MCC = 302IMSI_11_12 = 00IMSI_S = 9055170325RELEASE = 0
RECORD_TYPE = Message WaitingRECORD_LEN = 8 bitsMSG_COUNT = 1RESERVED = 0
FEATURE NOTIFICATION MESSAGE
The Feature Notification Message onthe 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!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 Measurement
Message to the system whenever triggered by: It notices a pilot in neighbor or remaining set
exceeds T_ADD
An active set pilot drops below T_DROP forT_TDROP time
A candidate pilot 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?
All PN Offsets0
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Ec/Io
0
0
32K
512
Chips
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/Io above T_ADD,
ask to use it! Send a Pilot Strength Measurement Message!
T_ADD
Rake Fingers
Reference PN
Active Pilot
10752
168
32000
500
14080
220
! !
Mobile Rake RX
Srch PN??? W0
F1 PN168 W61
F2 PN168 W61
F3 PN168 W61
Mobile Requests the Handoff!
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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 Disabled
REF_PN = 168 Offset Index (the Reference PN)PILOT_STRENGTH = -6.0 dBKEEP = 1PILOT_PN_PHASE = 14080 chips (PN220+0chips)PILOT_STRENGTH = -12.5 dBKEEP = 1PILOT_PN_PHASE = 32002 chips (PN500 + 2 chips)PILOT_STRENGTH = -11.0 dB
KEEP = 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 168
and 220.This pilot strength measurement messagereports PN 500 has increased aboveT_Add, and the mobile wants to use it too.
The base station acknowledges receiving
the Pilot Strength Measurement Message.
System Authorizes the Handoff!
HANDOFF DIRECTION MESSAGE
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98/05/24 23:14:02.926 [FTC] Extended Handoff Direction MessageMSG_LENGTH = 136 bitsMSG_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 chips
T_ADD = -13.0 dB T_DROP = -15.0 dB T_COMP = 2.5 dBT_TDROP = 4 secHARD_INCLUDED = 0FRAME_OFFSET = Field OmittedPRIVATE_LCM = Field Omitted RESET_L2 = Field OmittedRESET_FPC = Field Omitted RESERVED = Field OmittedENCRYPT_MODE = Field Omitted RESERVED = Field OmittedNOM_PWR = Field Omitted NUM_PREAMBLE = Field OmittedBAND_CLASS = Field Omitted CDMA_FREQ = Field Omitted
ADD_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
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 use
Walsh 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 OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0
MOBILE STATION ACKNOWLEDGMENT
Mobile Implements the Handoff!
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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 MessageMSG_LENGTH = 72 bitsMSG_TYPE = Handoff Completion MessageACK_SEQ = 6 MSG_SEQ = 1 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledLAST_HDM_SEQ = 0PILOT_PN = 168 Offset Index
PILOT_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!
NEIGHBOR LIST UPDATE MESSAGE
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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 MessageMSG_LENGTH = 192 bitsMSG_TYPE = Neighbor List Update MessageACK_SEQ = 1 MSG_SEQ = 7 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledPILOT_INC = 4 Offset IndexNGHBR_PN = 164 Offset IndexNGHBR_PN = 68 Offset Index
NGHBR_PN = 52 Offset IndexNGHBR_PN = 176 Offset IndexNGHBR_PN = 304 Offset IndexNGHBR_PN = 136 Offset IndexNGHBR_PN = 112 Offset IndexNGHBR_PN = 372 Offset IndexNGHBR_PN = 36 Offset IndexNGHBR_PN = 8 Offset Index
NGHBR_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
In response to the mobiles HandoffCompletion Message, the base stationassembles a new composite neighbor
list including all the neighbors of each ofthe three active pilots.This is necessary since the mobilecould be traveling toward any one ofthese pilots and may need to request
soft handoff with any of them soon.
The mobile confirms receiving theNeighbor List Update Message. 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!
All PN Offsets0
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Ec/Io
0
0
32K
512
Chips
PN
-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
168
32000
500
14080
220
T_DROP
Mobile Rake RX
Srch PN??? W0
F1 PN168 W61
F2 PN500 W50
F3 PN220 W20
The Complete Picture of Handoff & Pilot Sets
o
All PN Offsets0
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T_ADD
Ec/Io
0
0
32K
512
Chips
PN
-20
Neighbor Set
SRCH_WIN_N
Active Set
Candidate SetT_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 W61
F2 PN500 W50
F3 PN220 W20
Timing of Pilot Searchers Measurement Process
CURRENT PILOT SET CONTENTS
R
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The searcher checks pilots in nestedloops, much like meshed gears.Actives and candidates
occupy the fastest-spinning wheel.
Neighbors arenext, advancingone pilot for eachAct+Cand. revolution.Remaining is slowest,
advancing one pilot eachtime the Neighbors revolve.
A 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 RR 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
31
12112
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 pilots have been checked thus far!
A
N
R
R
R
R
R
R
NN
N
N
N
N
NN
AA
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.
Troubleshooting Call Events:Watch Messaging, Mobile State
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Your current capabilities Earlier in this course we reviewed handset call processing
states
You have just seen the entire vocabulary of messages
ordinarily 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 302
CDMA Performance Indicators
and Problem Signatures
CDMA Performance Indicators
and Problem Signatures
Introducing CDMA RF Performance Indicators
Earlier we compared a Cockpit Voice Recorder in aviation to the message
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files captured by CDMA drive-test equipment. Continuing this analogy, a Flight Data Recorder logs aircraft operational
settings. Its CDMA equivalent is a file of RF performance indicatorscaptured by drive-test equipment.
Key CDMA parameters and measurements show the condition of the RFenvironment. They are the primary gauges used to guide CDMAoptimization and troubleshooting
some indicate uplink conditions, some downlink, and some, both.
these parameters are collected primarily at the subscriber end of the
link, and thus are easy to capture using readily available commercialequipment without requiring assistance at the BSC
Understanding these parameters and their important implications requiresbasic knowledge in several subject areas:
General: RF units, transmitter and receiver basics
CDMA and spread-spectrum signal characteristics channel definitions
power control systems
basic CDMA call processing flow
signal behavior characteristics in noise and interference
Key CDMA RF Performance Indicators
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FER Frame Erasure Rate on forward channel
(realized at Handset)
on reverse channel
(realized at base station) FER is an excellent call
quality summary statistic
Mobile Receive Power
usually expressed in dBm
measured derived fromhandset IF AGC
broadband, unintelligentmeasurement: includes allRF in the carrier bandwidthregardless of source, not
just RF from serving BTS
-40
-90
-105
>RX Level
FER
%
0 2 5 100
Forward
Reverse
x
LO
RX Level(from AGC)
IFLNA
BW~30
MHz.
BW1.25MHz.
Handset Receiver
R
R
R
S
Rake
More Key CDMA RF Performance Indicators
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Ec/Io cleanness of the pilot
foretells the readability ofthe associated traffic
channels guides soft handoff decisions digitally derived: ratio of good
to bad energy seen by the
search correlator at thedesired PN offset Never appears higher than
Pilots percentage of servingcells transmitted energy
Can be degraded by strongRF from other cells, sectors
Imperfect orthogonality,other PNs are ~-20 dB.
Can be degraded by noise
Ec/Io dB
-25 -15 -10 0
Ec
Io
Energy of
desired pilot alone
Total energy received
Li ht T ffi L di
How Ec/Io Varies with Traffic Loading
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Light Traffic Loading
Heavily Loaded
Each sector transmits a certainamount of power, the sum of:
pilot, sync, and paging
any traffic channels in useat that moment
Ec/Io is the ratio of pilot powerto total power
On a sector with nobodytalking, Ec/Io is typicallyabout 50%, which is -3 db
On a sector with maximum
traffic, Ec/Io is typicallyabout 20%, which is -7 db.
Ec/Io = (2/4)= 50%
= -3 db.
Ec/Io = (2/10)
= 20%= -7 db.
2w
1.5w
Pilot
Paging
Sync
I0
EC
TrafficChannels
6w
0.5w
2w
1.5w
Pilot
Paging
Sync I0EC
0.5w
O S t D i t
How Ec/Io varies with RF Environment
I l it ti
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Many Sectors, Nobody Dominant
One Sector Dominant In a clean situation, onesector is dominant and themobile enjoys an Ec/Io justas good as it was when
transmitted In pilot pollution, too many
sectors overlap and themobile hears a soup madeup of all their signals
Io is the power sum of allthe signals reaching themobile
Ec is the energy of a
single sectors pilot The large Io overrides the
weak Ec; Ec/Io is low!
Io = -90 dbmEc = -96 dbmEc/Io = -6 db
Io = 10 signalseach -90 dbm
= -80 dbmEc of any onesector = -96
Ec/Io = -16 db
2w
1.5w
Pilot
Paging
Sync
I0
EC
Traffic
Channels
4w
0.5w
BTS1
I0
EC
BTS2
BTS3
BTS4
BTS5
BTS6
BTS7
BTS8
BTS9
BTS10
PilotSync & Paging
Traffic
PilotSync & Paging
Traffic
PilotSync & Paging
Traffic
Pil