CDMA Channel Structure
CBB_T02_E2
ZTE University
CDMA-BSS Team
Main Content
The forward channels in IS-95
The reverse channels in IS-95
CDMA Call Processing
New Channels in CDMA20001X
IS-95A Channels
Pilot Channel
•Used by the mobile station for initial system acquisition•Transmitted constantly by the base station•The same Short PN sequences are shared by all base stations, Each base station is differentiated by a phase offset•The function of Pilot channel is to search the serving sectors
•Used by the mobile station for initial system acquisition•Transmitted constantly by the base station•The same Short PN sequences are shared by all base stations, Each base station is differentiated by a phase offset•The function of Pilot channel is to search the serving sectors
Ec
Io
Energy of received pilot alone
Total energy received
Ec/IoMeasures the “strength” of the pilot
Ec/IoMeasures the “strength” of the pilot
Sync Channel
(Acquired Pilot)
Sync Channel
•Used to provide essential system parameters
•Mobile Station re-synchronizes at the end of every call
•Used to provide essential system parameters
•Mobile Station re-synchronizes at the end of every call
Sync Channel - continued
MSG_TYPE (‘00000001’)MSG_TYPE (‘00000001’)
P_REVP_REV
MIN_PREVMIN_PREV
SIDSID
NIDNID
PILOT_PNPILOT_PN
LC_STATELC_STATE
SYS_TIMESYS_TIME
LP_SECLP_SEC
LTM_OFFLTM_OFF
DAYLTDAYLT
PRATPRAT
CDMA_FREQCDMA_FREQ
88
88
88
1515
1616
99
4242
3636
88
66
11
22
1111
Field Length(bits)
Total : 170
System IDNetwork IDShort PN offset indexLong PN code statusSystem Time
Paging channel rateCDMA frequency assignment
Sync Message Parameters
Message Type (MSG_TYPE) – Identifies this message and determines its structure (set to the fixed value of ‘00000001’)
Protocol Revision Level (P_REV) – Shall be set to ‘00000001’Minimum Protocol Revision Level (MIN_P_REV) – 8-bit unsigned integer identifying the
minimum protocol revision level required to operate on the system. Only mobile stations that support revision numbers greater than or equal to this field can access the system.
System ID (SID) – 16-bit unsigned integer identifying the systemNetwork ID (NID) – 16-bit unsigned integer identifying the network within the system (defined
by the owner of the SID)Pilot PN Sequence Offset Index (PILOT_PN) – Set to the pilot PN offset for the base station
(in units of 64 chips), assigned by the network plannerLong Code State (LC_STATE) – Provides the mobile station with the base station long code
state at the time given by the SYS_TIME field, generated dynamicallySystem Time (SYS_TIME) – GPS system-wide time as 320 ms after the end of the last
superframe containing any part of this message, minus the pilot PN offset, in units of 80 ms, generated dynamically
Sync Channel MessageParameters (cont.)
Leap Seconds (LP_SEC) – Number of leap seconds that have occurred since the start of system time (January 6, 1980 at 00:00:00 hours) as given in the SYS_TIME field, generated dynamically
Local Time Offset (LTM_OFF) – Two’s complement offset of local time from system time in units of 30 minutes, generated dynamically
Current local = SYS_TIME – LP_SEC + LTM_OFFDaylight savings time indicator (DAYLT) – Determined by the network
planner1 if daylight savings in effect in this base station0 otherwise
Paging Channel Data Rate (PRAT) – The data rate of the paging channel for this system, determined by the network planner
00 if 9600 bps01 if 4800 bps
CDMA Frequency Assignment (CDMA_FREQ)
Paging Channels
Paging Channel
Used by the base station to transmit system overhead informationand mobile station-specific messages.
Used by the base station to transmit system overhead informationand mobile station-specific messages.
There is one paging channel per sector per CDMA carrier
The Paging Channel uses Walsh function 1
Two rates are supported: 9600 and 4800 bps
Paging Channel - continued
Mobile-Station-Directed Messages
Mobile-Station-Directed Messages
OverheadMessages
OverheadMessages
Access Parameters MessageAccess Parameters Message
System Parameters MessageSystem Parameters Message
CDMA Channel List MessageCDMA Channel List Message
Extended System Parameters MessageExtended System Parameters Message
Extended Neighbor List MessageExtended Neighbor List Message
ConfigurationParameterMessages
ConfigurationParameterMessages
Global Service Redirection MessageGlobal Service Redirection Message
PagingMessagesPaging
Messages
ACC_MSG_SEQ
CONFIG_MSG_SEQ
Paging Channel Time Slot Structure
7
6
5
4
3
2
1
0
SCI 163.84 s
T = 2 SCI
SCI = Slot Cycle IndexT = Slot Cycle Length in 1.28 s unitsHow often: 1.28* T 80 ms
1.28 s
CDMA Forward Traffic Channels
Forward Traffic ChannelForward Traffic Channel
Sync
Paging
Forward Traffic Channel
Forward Traffic Channel
Pilot
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CDMA Cell Site
Used for the transmission of user and signaling information to aspecific mobile station during a call.
Maximum number of traffic channels: 64 minus one Pilot channel, one Sync channel, and 1 Paging channel.
This leaves each CDMA frequency with at least 55 traffic channels.Unused paging channels can provide up to 6 additional channels.
CDMA Forward Channels
BTS (1 sector)MSC BSC
FECWalsh #1
Sync FECWalsh #32
Walsh #0
FECWalsh #12
FECWalsh #23
FECWalsh #27
FECWalsh #44
Pilot
Paging
Vocoder
Vocoder
Vocoder
Vocoder
Other users
Trans-mitter,
Sector X
Σ
I QPN120
Main Content
The forward channels in IS-95
The reverse channels in IS-95
CDMA Call Processing
New Channels in CDMA20001X
Reverse Access Channels
Access channel
Used by the mobile station to:Initiate communication with the base stationRespond to Paging Channel messages
Has a fixed data rate of 4800 bps
Each Access Channel is associated with only one Paging Channel
CDMA Reverse Traffic Channels
Reverse Traffic Channel
Used when a call is in progress to send:Voice traffic from the subscriberResponse to commands/queries from the base station Requests to the base station
Reverse Channels Generation and Demodulation
MSC BSC BTS (1 sector)
Channel Element
Access Channels
Vocoder
Vocoder
Vocoder
Vocoder
Receiver,Sector X
Channel Element
Channel Element
Channel Element
Channel Element
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
Long Code Gen
其它用户
UserLongCode User
LongCode User
LongCode
UserLongCode
UserLongCode
UserLongCode
•Each mobile is uniquely identified by the User Long Code, which it generatesinternally.•All mobile stations transmit simultaneously on the same 1.25 MHz wide frequency band.
•Each mobile is uniquely identified by the User Long Code, which it generatesinternally.•All mobile stations transmit simultaneously on the same 1.25 MHz wide frequency band.
•Any nearby BTS can dedicate a channel element to the mobile station and successfully extract its signal.
•Any nearby BTS can dedicate a channel element to the mobile station and successfully extract its signal.
Main Content
The forward channels in IS-95
The reverse channels in IS-95
CDMA Call Processing
New Channels in CDMA20001X
CDMA MS Call Processing
Power-UpPower-Up
InitializationInitialization
IdleIdle
SystemAccess
SystemAccess
TrafficTraffic
Mobile station has fully acquired
system timing
Mobile station receives a Paging Channel message requiring ACK or response, originates a call, or
performs registration
Mobile station is directed to a Traffic Channel
Mobile station ends use of the Traffic Channel
Mobile station receives an ACK to an Access Channel transmission
other than an Origination Message or a Page Response Message
Mobile station is in idle handoff with NGHBR_CONFG equal to
‘011’ or is unable to receive Paging Channel Message
Main Content
The forward channels in IS-95
The reverse channels in IS-95
CDMA Call Processing
New Channels in CDMA20001X
CDMA2000-1X New Features
High speed 307.2 kbps packet data capabilities;
Increased mobile standby battery life;
Total backward compatibility to reuse switch and call processing features;
CDMA2000 1x RF Capacity
CDMA2000 1xRtt Channels
1x New Channels in Commercial Network
IS-95B built on the IS-95A channels, and introduced two new channelsFundamental channel was the same as IS-95A traffic channelSupplemental code channels assigned to support rates above 14.4Kbps
IS-2000 1xRTT continue to build on the IS-95 channelsIS-95 channels continue to be supported in IS-2000 to support IS-95 mobiles
Pilot channel Sync channel Paging channel Access channelForward Traffic Channel Reverse Traffic Channel
Supplemental channel (F-SCH) Supplemental channel (R-SCH)Quick Paging channel (F-QPCH) Reverse Pilot channel (R-PICH)
Forward Reverse
IS-95A
1xRTT
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