Post on 14-Jan-2016
Section 4: cdma2000 MAC Overview
1
Section 4:Section 4:
cdma2000 MACcdma2000 MAC
Section 4: cdma2000 MAC Overview
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What cdma2000 MAC ProvidesWhat cdma2000 MAC Provides• The cdma2000 MAC sublayer provides:
– MAC Control States - procedures for controlling the access of data services (packet and circuit) to the physical layer;
– Best Effort Delivery - reasonably reliable transmission over the radio link with a Radio Link Protocol (RLP) that provides a “best effort” level of reliability; and
– Multiplexing and QoS Control - enforcement of negotiated QoS levels by mediating conflicting requests from competing services and the appropriate prioritization of access requests.
– Enhanced Access Procedures
Section 4: cdma2000 MAC Overview
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Channel NamingChannel Naming
• Example: f-csch = Forward Common Signaling CHannel
Table 1. Convention for Logical Channel Naming
1ST LETTER 2ND LETTER 3RD LETTER
f = Forwardr = Reverse
d = Dedicatedc = Common
t = Trafficm = MACs = Signaling
ChannelName
Physical Channel
F/ R-FCH Forward/ Reverse Fundamental Channel
F/ R-DCCH Forward/ Reverse Dedicated Control Channel
F/ R-SCCH Forward/ Reverse Supplemental Code Channel
F/ R-SCH Forward/ Reverse Supplemental Channel
F-PCH Paging Channel
F-QPCH Quick Paging Channel
R-ACH Access Channel
F/ R-CCCH Forward/ Reverse Common Control Channel
ChannelName
Physical Channel
F/ R-PICH Forward/ Reverse Pilot Channel
F-APICH Dedicated Auxiliary Pilot Channel
F-TDPICH Transmit Diversity Pilot Channel
F-ATDPICH Auxiliary Transmit Diversity Pilot Channel
F-SYNCH Sync Channel
F-CPCCH Common Power Control Channel
F-CACH Common Assignment Channel
R-EACH Enhanced Access Channel
F-BCH Broadcast Channel
Section 4: cdma2000 MAC Overview
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Logical ChannelsLogical Channels Dedicated Traffic Channels (dtch) –
data channel dedicated to a single PLICF instance;
Common Traffic Channels (ctch) –
data channel with shared access among many mobile stations and/or PLICF instances;
Dedicated Signaling Channels (dsch) –
Upper Layer Signaling data dedicated to a single PLICF instance; and
Common Signaling Channels (csch) –
Upper Layer Signaling data with shared access among many mobile stations and/or PLICF instances.
Section 4: cdma2000 MAC Overview
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cdma2000 MAC State Transitionscdma2000 MAC State Transitions
Big Timeout
Traffic
TIA/EIA-95-BMAC
Inactivity
Traffic
Inactivity
Traffic
Inactivity
Traffic
cdma2000MAC
Traffic, PC, &Control ChannelsAssigned
No DedicatedChannels
No BS, MSCResources
PPP StateMaintained
Short Data Bursts(cdma2000 only )
No DedicatedChannels
ServiceConfigurationMaintained
RLP & PPP StateMaintained
PC & ControlChannelsAssigned
Very Fast TrafficChannelReassignment
ActiveState
DormantState
Inactivity
Inactivity
Inactivity
ControlHoldState
DormantState
SuspendedState
ActiveState
Section 4: cdma2000 MAC Overview
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Packet Data StatesPacket Data States• Active State
– Dedicated traffic channels (e.g., fundamental or supplemental) are allocated;
– The Activity Timer starts when no traffic is exchanged and reset when there is traffic to be exchanged;
– Traffic channel is released when the Activity Timer expires.
• Control Hold State
– A dedicated control channel is maintained on which MAC control commands (e.g., to begin a high speed data burst) can be transmitted.
– Power control is also maintained so that high speed burst operation can begin with minimum delay.
– Reverse pilot may be transmitted in a “gated” mode (i.e. with a duty cycle of less than one) to reduce interference and save power
Section 4: cdma2000 MAC Overview
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Packet Data States (cont’d)Packet Data States (cont’d)• Suspended State
– No dedicated channels to or from the user are maintained
– The state information for RLP is maintained
– Active Set is stored by the BS so that if the Active Set is not changed the BS can instruct the MS to use the stored Active Set
– Service Configuration Record is stored by the BS (to avoid Service Negotiation)
– Mobile may continue monitoring the Paging Channel in the non-slotted mode for a shot time interval (~ 1-2 sec) after dropping the dedicated channels. This expedites a transition to the Active State shortly after the dedicated channels are released.
Section 4: cdma2000 MAC Overview
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Example of Packet Data State TransitionExample of Packet Data State Transition
In Suspended State In Null State; RMAC PLICF in the DormantStateIn Active State Control Hold State
Release Message issent by the BS
T Suspended
Exchanging user DataNot Exchanging
user Data
tim e
Dedicated channels are allocatedThere is at least one
dedicated channel; powercontrol is m aintained
tim e
No dedicated channel is allocated
T hold
PPP is open and call/RLP states are retainedPPP is open but call/RLP states
are not retained
tim e
a
b c d
e
Send a"short"packet
NotExchanginguser Data
dsch and dtch are notallocated;
dsch and dtch are notallocated;
using the ctch
Dorm antIdle
Dorm antBurst
Dorm antIdle
States
T active
dsch and dtch are notallocated;
m onitoring com m onchannels
Section 4: cdma2000 MAC Overview
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State Transition ExampleState Transition ExampleActive/CHS
CHS
Suspended Normal
Suspended Slotted
Dormant
Forward
Reverse
F ig u r e 1 . S n a p s h o t o f F o r w a r d a n d R ev er s e L in k T r a ffi c (d i s ta n c e b etw een ea c h l i n e i so n e s ec o n d )
Section 4: cdma2000 MAC Overview
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cdma2000 Layered Structurecdma2000 Layered Structure
Physical Layer
S ignalingServices
PPP
Packet DataApplication
TCP UDP
VoiceServices
O SILayers
3-7
O SILayer
2
O SILayer
1
C ircuit DataApplication
H igh SpeedC ircuit NetworkLayer Services
M ediumAccessContro l(M AC)
Link AccessContro l (LAC)
LAC Protocol Null LAC
M ACContro lS tates
Best E ffort Delivery(RLP)
M ultip lexing
IP
Q oS Contro l
Unique tocdm a2000
Section 4: cdma2000 MAC Overview
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Simplified Layered ArchitectureSimplified Layered ArchitectureData PlaneControl Plane
DCRPLICF
RLPQueue
Mux and QoS Sublayer
Voice LAC(or Null)
Null ARQ
Mux andQoS
Control
F/R
-C
CC
H
F/R
-FC
H
F/R
-D
CC
H
AC
H
PC
H
Physical LayerCoding and Modulation
F/R
-SC
H
ResourceControl
VoicePLICF
Re
so
urc
eC
on
fig
ura
tio
nD
ata
ba
se Data
ServicePLICF(s)
DataService
PLICF(s)
DataServicePLICF
SRBP RLP
SignalingControlUpper
Layers
LACSublayer
PLICFSublayer
InstanceSpecificPLDCF
Sublayer
PLDCFand
Mux andQoS
Sublayer
PhysicalLayer
TCP/UDP
IP
PPP
Voice
DCR
RBP
Data LAC(or Null)
QueueStatus
andControl
UpperLayer
Signaling
SignalingData
DCRPLICF
DCRPLICF
Voice Application(Vocoder)
Voice Application(Vocoder)
Voice Application(Vocoder)
Data ApplicationData ApplicationData Application
TCP/UDP
IP
PPP
TCP/UDP
IP
PPP
V oice
UserData
Sig
na
lin
g t
o P
hys
ica
l L
aye
r In
terf
ac
e
Voice
SignalingLAC
f/r-dsc
h
f/r-dtc
h
f/r-dtc
h
f/r-cs
ch
SDBTS
Section 4: cdma2000 MAC Overview
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Functional Entity DefinitionsFunctional Entity Definitions• Signaling
– Performs Channel Assignment, Service Negotiation, Handoff, etc
• Data Service PLICF– Interacts with the Resource Control and the Peer PLICF to coordinate
state transitions between the MS and BS
• DCR (Dedicated/Common Router) PLICF– Controls the behavior of the BS/MS when in Dormant State
• MUX & QoS– realtime prioritization of the use of dedicated traffic resources
– Mux/de-Muxing of the logical channels from/to different physical channels based on the Logical to Physical Mapping table (LPM)
Section 4: cdma2000 MAC Overview
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Resource ControlResource Control
• Locks and Unlocks resources and harmonizes state transition across multiple PLICFs
• Maintains a database to control the operating configuration of the mobile, including
– the current logical to physical channel mapping, and
– the currently defined physical channel configuration (e.g., dedicated vs. common control operation; number of active SCHs; DCCH vs. FCH; etc.).
sr_id=1
sr_id=3
dtch
dmch
… … …
= Locked
blank = unlocked
sr_id = Service Reference ID
Section 4: cdma2000 MAC Overview
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State Transitions: Active StateState Transitions: Active State
Locked U nlocked
Receives RC-Released.Indication(dtch)Send Q -S topXm it.R equest
Send T -S tart.R equest(H old_T im er)
Control Hold State
Receives RC-Unlock.Confirm(dtch)
Receives T-Expired.Indication(Activity_Timer)
Send R C -U nlock.R equest(d tch)
Active State (BS)
Receives Q-BufferEmpty.IndicationSend T-S tart.R equest(Activ ity_T im er)
Suspended or Control Hold States
1
2
30
Active Control Hold
Section 4: cdma2000 MAC Overview
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Simplified State TransitionsSimplified State Transitions
Locked Unlocked
Null State
Control Hold State
Unlocked
Active State
Locked
Suspended State
Receives T-Expired.Indication(Hold_Tim er)Sends R C -U nlock.R equest(dm ch)
ReceivesT-Expired.Indication(Suspended_Tim er)
Sends R C -U nlock.R equest(SR ) Receives RC-Unlock.Confirm (SR)
Receives RC-Unlock.Confirm (dm ch)
Receives RC-ResourceReleased.Indication(dm ch)Sends T-S tart(Suspended_T im er)
ReceivesRC-ResourceReleased.Indication(SR)
0
1
2
3
4
5
6
Active Control Hold Suspended
Section 4: cdma2000 MAC Overview
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Multiple ServicesMultiple Services
• Multiple services with different characteristics may be connected simultaneously.
• The Resource Control coordinates amongst multiple services
• State transitions are synchronized (i.e. the RC assures that all the services make the state transition at the same time)
• This synchronization is necessary because each state (e.g., Active, Suspended) has a certain set of attributes that correspond to the behavior of the BS/MS as a whole
Section 4: cdma2000 MAC Overview
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Dragging ExampleDragging Example
Time
PLICF AState
Resource
PLICF BState
Resource
ResourceControl
SuspendedTraffic...
Allocate dmch, dtch
Confirm
Allocate Indication dmch, dtch
Suspended
Active
dmch, dtch
Active
dmch, dtch
...Control Hold
dmch
Unlock dtch Release Indication dtch
Control Hold
dmch
PLICF B Draggedto Active...
Release Indication dtch
PLICF B Draggedto Control Hold...
• Service ‘A’ requests for a transition to Active from Suspended
• Service ‘B’ gets dragged up to Active as well
Section 4: cdma2000 MAC Overview
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Dangling ExampleDangling Example
Time
PLICF AState
Resource
PLICF BState
Resource
ResourceControl
Control Hold
dmch
Timeout...
Unlockdmch
Release Indication dmch
Control Hold
dmch
Suspended
Suspended
...
Timeout...
Unlockdmch
Release Indication dmch
PLICF A Dangling...
• Service ‘A’ requests for a transition to Control Hold from Suspended
• Service ‘A’ dangles in the Control Hold state until service ‘B’ is ready to make the transition
Section 4: cdma2000 MAC Overview
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Multiple Services: Releasing Resources and DanglingMultiple Services: Releasing Resources and Dangling
Active StateActive State
Locked
•Timer expires•Send Request for releasing dtch
•Timer expires•Send Request for releasing dmch
Unlocked
•RC confirmation
Unlocked
•RC confirmation
Locked
•Timer expires•Send Request for releasing dtch
•Timer expires•Send Request for releasing dmch
Unlocked
•RC confirmation
Unlocked
•RC confirmation
•RC releases dmch •RC releases dmch
Locked
•RC releases dtch
Locked
•RC releases dtch
PLICF_A PLICF_B
[1]
[2]
[3]
[4]
[5][5]
[6]
[7]
[8]
[9]
[10] [10]
Control Control Hold StateHold State
Active Control Hold
Section 4: cdma2000 MAC Overview
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Multiple Services: Allocating Resources and DraggingMultiple Services: Allocating Resources and Dragging
Active StateActive State Unlocked
Unlocked
Locked
•RC Lock confirmation
•Have Data to Send•Send Request for Allocating dtch
UnlockedLocked Locked
Locked Unlocked
Receives Confirmation for Allocation of dtch
Receives Indication for Allocation of dtch
PLICF_A PLICF_B
•Has Data to Send•Send Request for locking dtch
[1]
[2]
[3]
[2]
[4]
Control Control Hold StateHold State
Control Hold Active
Section 4: cdma2000 MAC Overview
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State Transition ProcedureState Transition Procedure
1 A PLICF locking or unlocking a logical resource
2 The RC determines if the request leads to a release or allocation of a physical resource
3 If a physical resource needs to be release or allocated, then the RC instructs the L3-Signaling to allocate or release the physical resource
L3Signaling
BS
R esourceC ontro l
PLICF
R esourceC ontro l
L3Signalin
g
PLICF
MS
N eed a logica lresource (e .g. d tch)
1
A lloca te FC H C hanne l A ssignm ent
2 3
FC H A lloca ted
4
dtch A lloca ted
5
Section 4: cdma2000 MAC Overview
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Mux SublayerMux Sublayer• Data block: A block of data that belongs to the
same service or signaling
• MuxPDU: MuxSDU + header– The header specifies the Signaling, Primary, or
secondary
• MuxPDU Type: determines– Rate Set (e.g., 1 or 2)
– how to parse the MuxPDU
MultiplexSublayer
Service 1(SR=1)
Service 2(SR=2)S ignaling
dsch dtch, sr=1
dtch, sr_id=2
data block data block
data block data block
Header(form at bits)
MuxPDUHeader
data block CRC data block
MUX PDU Type 3
LTU
CRC
SCH SDU
FCH SDU
MUX PDU Type 1 or 2
MuxPDUHeader
LPM Table
data block
data block
• Mux Option: determines– max number of MuxPDUs on the SCH
– Single-size or double-size MuxPDUs
– Mux PDU Type
• LTU: Logical Transmission unit:– 1, 2, 4, or 8 MuxPDUs that are protected by a CRC
which is added at the MUX sublayer
Section 4: cdma2000 MAC Overview
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PDU Types and New Mux OptionsPDU Types and New Mux Options
Example:
• Mux Option 0x906: Maximum 1 double-size MuxPDU Type 3
• Mux Option 0x822: Maximum 4 single-size MuxPDU Type 3
Fields Used to Compute Multiplex Option Numbers Greater than 0x10
Field Name Number of Bits Value
Rate_Set 2 ‘01’ – Rate Set 1‘10’ – Rate Set 2
LeastSignificantBit
Max_Data_Blocks 6 ‘000001’ – ‘001000’
Data_Block_Size 2‘00’ – Single size‘01’ – Double size
MuxPDU_Type 2‘00’ – MuxPDU Types 1, 2, or 4‘10’ – MuxPDU Type 3
Format_Descriptor 4 ‘0000’ – Format 1MostSignificantBit
Multiplex Options Applicable to an SCH
Multiplex OptionMaximum Number ofMuxPDUs in the Physical
Layer SDU Rate Set 1 Rate Set 2
MuxPDU Type 3 MuxPDU Type 3 MuxPDU Type 3
SCHRate
MuxPDUType 1 or 2 single double
MuxPDUType 1 single double
MuxPDUType 2 single double
1x 1 0x03 0x042x 2 1 0x809 0x905 0x80a 0x9064x 4 2 0x811 0x909 0x812 0x90a
8x 8 4 0x821 0x911 0x822 0x91216x 8 0x921 0x922
Note: SCH Rate is expressed in multiples of a base rate. For Rate Set 1, the base rate is 9600 bps,and for Rate Set 2, the base rate is 14400 bps. Thus a 2x SCH rate means twice 9600 for Rate Set 1(19200), or twice 14400 for Rate Set 2 (28800).
MuxPDU Type 1 and 2 N bitsS pecified by the M ultip lex O ption fo r a FC H or
D C C H or S C C H or R ate 1x S C H
M uxP D U header (identica l to the T IA /E IA -95-B fo rm at b its)
MuxPDU Type 3 6 bitsS pecified by the M ultip lex O ption fo r a R ate 2x or
la rger S C H
sr_ id3 b its
R eserved3 b its
M uxP D U header
MuxPDU Type 4 0 bitsS pecified by the M ultip lex O ption fo r a 5 m s
M uxP D U for the FC H or D C C H
'000 '
Section 4: cdma2000 MAC Overview
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Resource Config. Database (RCD)Resource Config. Database (RCD)
Resource Configuration Database
ESC AM ,F/R SC AM M
SIG C ontro l P rim itives
Supplem ental Channel Code List Table for FOR_SCH_ID = 1 FOR_SCH NUM_SUP {{QOF, FOR_SCH_CC_INDEX,
Index _RATE _SHO PN_OFFSET}, ...}'0000' '0001' 1 {{'00', '10101011101', '001101100'}}'0001' '0010' 1 {{'00', '10101011101', '101101101'}}'0010' '0101' 1 {{'00', '10101011101', '101101101'}} ...'1111' '0010' 1 {{'00', '10101011101', '101101101'}}
Supplem ental Channel Code List Table for FOR_SCH_ID = 0SCCL_ FOR_SCH {{QOF, W alsh, PN_OFFSET}, ...}Index _RATE '0000 ' '0001 ' {{'00 ', '10101011101 ', '001101100 '}, ...}'0001 ' '0010 ' {{'00 ', '10101011101 ', '101101101 '}, ...}'0010 ' '0101 ' {{'00 ', '10101011101 ', '101101101 '}, ...} ...'1111 ' '0010 ' {{'00 ', '10101011101 ', '101101101 '}, ...}
Logical to Physical Mapping Tablesr_id Log. Res. Priority f/r Physical Resource1 dtch 3 F /R FC H2 dtch 2 F /R D C C H , S C H 03 dtch 2 F /R FC H , S C H 12 dm ch 1 F/R D C C H3 dm ch 2 F/R FC Hn/a dsch 1 F/R FC H
1,2 ,3 d tch n /a R C O N T _R E V _P ILO T1,2 ,3 S R n/a F /R S O _IN S T A N C E
SR Mapping TableLogical
sr_id Locked?a Resource1 Y dtchn /a Y dsch1 Y S R
2 N dtch2 Y dm ch2 Y S R
3 Y dtch3 Y dm ch3 Y S R
Serv
ice C
onnect
Mess
age, U
niv
ers
al H
andoff D
irect
ion M
ess
age
RC-AllocateAndLock(), RC-Lock(), RC-
Unlock()
Notes:a: Not included in the RCD on the mobile station.
Extended Supplem enta l C hannel Assignm ent M essage
Supplem ental Burst Table SCCL_IndexDirection FOR_SCH_ID Start_Tim e Duration or RateF S C H 0 '000010 ' '0011 ' '0001 'F S C H 1 '000101 ' '0100 ' '0010 'R S C H 0 '000011 ' '1111 ' '0010 '
Exte
nded C
hannel A
ssignm
ent M
essa
ge, S
ervice
Connect M
essa
ge
Data ServicePLICF
PhysicalLayer
Mux and QoSControl
Mux and QoSLayer
Physical Layer ControlData ServiceDCR PLICFsand PLICFs
Physical Physical Channel TableChannel Locked?a Rates Var. Rate QOF W alsh Mux Opt. CCR -FC H Y '1111 ' Y n/a n /a 1 C C _r_ fchF-FC H Y '1110 ' Y '00 ' W 1 1 C C _f_ fchR -D C C H Y n/a N n/a n /a 1 C C _r_dcchF-D C C H Y n/a N '00 ' W 2 1 C C _f_dcchR -S C H 0 Y n/a N n/a w1 0x80a C C _r_sch0F-S C H 0 Y n/a N '00 ' n /a b 0x80a C C _f_sch0R -S C H 1 Y n/a N n/a w2 0x812 C C _r_sch1F-S C H 1 Y n/a N '00 ' n /a b 0x812 C C _f_sch1R -P IC H Y n/a N n/a n /a n /a n /a
ResourceControl
Upper Layer Signaling
Service Instance Tablesr_id SSR_ID CON_REF SO1 prim ary 1 12 secondary 3 163 N U LL 7 39
Section 4: cdma2000 MAC Overview
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RRC MessagesRRC Messages• Extended Supplemental Channel Assignment Message (20 ms)
– For each Supplemental Channel it specifies:
» Units of Start Time
» A list of Active Sets for F-SCH (PN codes, Walsh Codes, and Quasi-orthogonal functions)
» Assignment
• Forward Supplemental Channel Assignment Mini Message (5 ms)– Specifies the Supplemental Ch. ID, Start Time, Duration, and an index to the list Active
sets
Supplemental Channel Code List Table for FOR_SCH_ID = 0SCCL_ FOR_SCH {{QOF, W alsh, PN_OFFSET}, ...}Index _RATE '0000 ' '0001 ' {{'00 ', '10101011101 ', '001101100 '}, ...}'0001 ' '0010 ' {{'00 ', '10101011101 ', '101101101 '}, ...}'0010 ' '0101 ' {{'00 ', '10101011101 ', '101101101 '}, ...} ...'1111 ' '0010 ' {{'00 ', '10101011101 ', '101101101 '}, ...}
Supplemental Burst Table SCCL_IndexDirection FOR_SCH_ID Start_Time Duration or RateF S C H 0 '000010 ' '0011 ' '0001 'F S C H 1 '000101 ' '0100 ' '0010 'R S C H 0 '000011 ' '1111 ' '0010 '
Section 4: cdma2000 MAC Overview
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RRC Messages (cont’d)RRC Messages (cont’d)• Reverse Supplemental Channel Assignment Mini Message (5 ms)
– Specifies the Supplemental Ch. ID, Start Time, Duration, and Rate
• Reverse Supplemental Channel Request Mini Message (5 ms)– Specifies the Supplemental Ch. ID, Requested Rate, and Requested
Duration.
Section 4: cdma2000 MAC Overview
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MAC Messaging (cont’d)MAC Messaging (cont’d)
BS M S
Ext. Supp. Ch. Assign. M sg.
F-SCAMM[SCCL_INDEX, DURATION,
START_TIM E ]
F-SCAMM[SCCL_INDEX, DURATION,
START_TIM E ]
Ext. Supp. Ch. Assign. M sg.
...
20 m s m sg.
5 m s m sg.
20 m s m sg.
Data on F-SCH
Data on F-SCH
5 m s m sg.
BS M S
R-SCAMM[RATE, DURATION,
START_TIM E ]...
5 m s m sg.
SCRMM[REQ_RATE , REQ_DURATION ]
Data on R-SCH
Reverse High-Rate Transmission
Forward High-Rate Transmission
Section 4: cdma2000 MAC Overview
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Existing IS-95 A/B AccessExisting IS-95 A/B Access
• IS-95 A/B access scheme is based on a slotted aloha protocol– access channel slots are non-overlapping
• Accessing mobiles send probes on R-EACH:– probes consist of:
» preamble portion (typically 80 ms)
» message portion (typically 120 ms)
• Acknowledgements are transmitted on the paging channel– acknowledgement time-out (typically 320 ms)
• If no acknowledgement is received, mobile increases power and tries again (i.e. power ramping)
– Access slotting is typically 200 ms
– back-off delays (multiple of 200 ms)
– persistence delay (multiple of 200 ms)
Section 4: cdma2000 MAC Overview
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IS-95A/B Access ProcedureIS-95A/B Access Procedure
Initial Power
Power Step
Access Probe Sequence
Preamble Segment Message Segment
1 -16 frames 3 - 10 frames
Access Channel Probe
TART
Section 4: cdma2000 MAC Overview
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Requirements for Improved AccessRequirements for Improved Access• Increase System Capacity
– Minimize power required to service transactions » reduce power on preamble for detection
» reduce power on message portion
» minimize message retransmission probability
– Facilitate better flow control and admissions policies
• Increase Throughput & Reduce Delay– Minimize service transaction times
» increased data rates (9.6, 19.2 and 38.4 kbps)
» shortened preamble
» reduce message error probability
» reduce protocol latency (i.e. slot duration, ack. timeout, etc.)
Section 4: cdma2000 MAC Overview
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Improved Access MethodsImproved Access Methods• Employ overlapped slotting
– make long code a function of slot time to prevent hard collisions
• Improve message error rate performance– closed loop power control
– employ adjustable step sizes
• Protocol Optimization:– reduce slot intervals, timeout params, etc.
– for very short messages, closed loop PC provides little gain
– closed loop PC can be used to correct gross inaccuracies in open loop estimate
– longer messages can be moved to a dedicated channel
– soft handoff can be used to improve access performance
Section 4: cdma2000 MAC Overview
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Overview of Proposed ApproachOverview of Proposed Approach• Reservation Multiple Access (RsMA) is composed of three
distinct access protocols:– Basic Access Mode (slotted aloha):
» best for very short messages (e.g. < 20 ms.)
» open loop power control only
» no soft handoff
– Power Controlled Access Mode (PCA):» best for latency sensitive applications
» closed loop power control on RL
» no soft handoff
– Reservation Mode (RsMA):» best for longer messages
» closed loop power control on RL
» soft handoff facilitated
Section 4: cdma2000 MAC Overview
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Access ChannelsAccess Channels
F-C P H C H
(Forw ardC om m on
P hys ica l C h .)
R -C P H C H
F-P IC H Forw ard P ilo t C hanne l
F -C A P IC H Forw ard C om m on A uxilia ry P ilo t C hanne l
F -C C H T(Forw ard
C om m on C h.Type)
R -C C H T
F-P C H Forw ard P ag ing C hanne l
F -C C C H Forw ard C om m on C on tro l C hanne l
R -A C H R everse A ccess C hanne l
R -C C C H R everse C om m on C on tro l C hanne l
F -S YN C Forw ard S ync C hanne l
R -E A C H R everse E anhanced A ccess C hanne l
F -C P C C H Forw ard C om m on P ow er C on tro l C hanne l
F -C A C H Forw ard C om m on A ss ignm en t C hanne l
(R everseC om m on C h.
Type)(R everseC om m on
P hys ica l C h .)
• Forward Link:» Common Power Control Channel (F-CPCCH)
» Channel Assignment Channel (F-CACH)
» Common Control Channel (F-CCCH)
• Reverse Link:» Reservation Access Channel (R-EACH)
» Common Control Channel (R-CCCH)
Section 4: cdma2000 MAC Overview
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Reverse Reservation Access Channel Reverse Reservation Access Channel
• Reverse Enhanced Access Channel (R-EACH)– Slotted Aloha random access channels
– multiple R-EACH’s per F-CCCH
• R-EACH is operated in 3 primary modes:– BA Mode: short messages sent
– PCA Mode: messages sent with closed loop PC
– RsMA Mode: reservation requests sent
• Data rates supported:– 9.6 kbps (20 ms frame),19.2 kbps (10, 20 ms frames), 38.4 kbps (5, 10, 20 ms frames)
• R-EACH Probe Structure: – BA Mode: aloha access probe (AAP) = initial preamble + message
– PCA Mode: message access probe (MAP) = initial preamble + mode request frame + message
– Reservation Mode: reservation access probe (EAP) = initial preamble + mode request frame
Section 4: cdma2000 MAC Overview
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Reverse Common Control ChannelReverse Common Control Channel• Reverse Common Control Channel (R-CCCH)
– Assigned dedicated access channels
– Multiple R-CCCH’s supported
– long code can be common or user specific (designated)
• Data rates supported :– 9.6 kbps (20 ms frame),19.2 kbps (10, 20 ms frames), 38.4 kbps (5, 10, 20 ms
frames)
• Soft Handoff :– 2-way soft handoff can be accommodated on the R-CCCH
» demod at 2 separate BTS’s
» PC independently from 2 BTS’s
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Forward Common Assignment ChannelForward Common Assignment Channel
• Forward Common Assignment Channel (F-CACH)– single Walsh code control channel supporting multiple R-EACH’s and
R-CCCH’s
– multiple F-CACH’s supported
• Modulation format:– single 128-chip Walsh code channel
– DTX, QPSK
– fixed 9.6 kbps; k=9, rate 1/2 conv. code
– fixed 5 ms message duration with CRC
• Messages:– BTS-level channel assignments/acknowledgements
– load & flow control (wait message)
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Forward Power Control ChannelForward Power Control Channel
• Forward Power Control Channel (F-CPCCH)– multiple F-CPCCH’s supported
– single Walsh code channel, divided into multiple sub-channels
– Each F-CPCCH subchannel supports a single R-EACH or R-CCCH
• Number of PC sub-channels per F-CPCCH – depends on PC rate which is a system parameter:
» 800 bps PC --> 24 subchannels per F-CPCCH
» 400 bps PC --> 48 subchannels per F-CPCCH
» 200 bps PC --> 96 subchannels per F-CPCCH
• Modulation format:– single 128-chip Walsh code channel
– DTX, uncoded QPSK
– fixed 9.6 kbps bit rate per I-Q phase branch
• Step Sizes– Access channel specific up & down steps.
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R-EACH Waveform DescriptionR-EACH Waveform Description
• Probe Preamble (sent in all modes):– integer number 1.25 ms.
– preamble can be divided into multiple ‘on’ and ‘off’ pieces
• Mode Request Frame (not sent in Basic Access Mode) – 5 ms frame, rate 1/2 coded message
– Message Fields:» mode indicator (1 bit): indicates PCA vs. Reservation mode
» Hash ID (16 bits):random or managed temporary mobile ID
» rate word (3 bits): indicates data rate and frame length of message
» neighbor PN (9 bits): PN offset of neighbor (set to 0 if no handoff requested)
» CRC (8 bits) and Tail bits (8 bits)
» reserved (3 bits)
• Message Portion (not sent in Reservation mode) – max. message duration is system parameter
– rate must be consistent with rate word in Mode Request Frame
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R-RCCCH Waveform DescriptionR-RCCCH Waveform Description
• Channel Estimation Preamble: – integer number 1.25 ms.
– preamble can be divided into multiple ‘on’ and ‘off’ pieces
• Long Code– common long code mask
– designated mode: user specific long code mask
• Message portion:– message is an integer number of frames
– max. duration is system parameter
– data rate must be consistent with resource grant
– CRC’s per frame
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F-CACH Waveform DescriptionF-CACH Waveform Description• fixed messages duration (5 ms.)
• Single 128-chip Walsh Code channel,
• QPSK modulation with r=1/2, k=9 conv. Coding
• Channel is DTX– no message --> no power
• Message types:– Channel assignment message fields:
– Wait message (admissions/flow control)
– 2 reserved message types
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F-CPCCH Waveform DescriptionF-CPCCH Waveform Description
• PC rate determines the number of PC sub-channels supported:– 24 @ 800 bps, 48 @ 400 bps, 96 @ 200 bps.
• The power control sub-channel id for each F-CPCCH is partitioned as follows:
Neighbor PCA Reservation
PCA_SCH_ADDR_OFFSET S
RES_SCH_ADDR_OFFSET S
RES_PCSCH SPCA_PCSCH S
PCA_SCH_ADDR in this areaspecified implic itly according to thetime the probe is sent
RES_SCH_ADDRin this areaspecified implic itlyaccording to thetime the probe issent
RES_SCH_ADDR forthe 2nd leg of soft HO
in this areaspecified explic itly in
PCCAM
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Admission/Flow ControlAdmission/Flow Control
• Admission/flow control:– Slow Response Time (~ 200 ms, typical):
» access parameters conveyed on F-BCCH give current persistence parameters and time-out values
– Moderate Response Time ( 5 ms):
» “wait message” is used to affect mobiles already accessing
» sent when “overload” or “all busy” condition is near or prevailing
» parameters affect:• flow on both the R-EACH and R-CCCH for reservation mode traffic
• system loading
» Inhibit Sense mode can be invoked:• mobiles required to examine F-CACH prior to transmitting
• behavior is ISMA-like
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Channel OrganizationChannel Organization
R-EACH
F-C
CC
H
R -EACH...
R-EACH
F-C
CC
H
R -EACH...
...R-CCCH R-CCCH R-CCCH
...
...
CPC_SCH
CP
CC
H
CPC_SCH...
CPC_SCH
CP
CC
H
CPC_SCH...
E cnhanced C om m on C hanne l S tructure
MS uses a random MS_IDto select an F-CCCH
BS uses the sam e MS_IDto select the F-CCCH
F-CACH F-CACH F-CACH
...
MS and BS select thisbased on the R-EACHaccess slot when the MShas started the access
MS selects one of theserandom ly and thenconstructs the long codem ask based on the R-EACH access slot whenthe MS has started theaccess
EACAM m essagespecifies the R-CCCHindex
In PCA m ode: MS and BS select thisbased on the R-EACH access slotwhen the MS has started the access
In RsMA m ode: EACAM specifies this
• R-EACH:– up to 32 per F-CCCH
• F-CACH:– up to 7 F-CACH’s supported
• R-CCCH:– up to 24 supported
• F-CPCCH:– up to 7 supported
– PC rate determines number of sub-channels per F-CPCCH
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Pure Aloha ProceduresPure Aloha Procedures
• mobile “randomly” selects from the corresponding R-EACH set and transmits a Enhanced Access Probe (EAP)
• mobile uses persistence parameters to regulate access attempts
• After EAP transmitted on R-EACH, mobile monitors F-CCCH for acknowledgement:
– If no ACK within time out, retry at higher power
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Basic Access ModeBasic Access Mode
Message Segment
Message Segment
Preamble
Preamble
R-EACH_1
R-EACH_1
R-EACH_1
R-EACH_1
R-EACH Slot
ACK. ACK. ACK. ACK.F-CCCH
Message SegmentPreamble
Message SegmentPreamble
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PCA ProceduresPCA Procedures
• Mobile “randomly” selects a R-EACH and transmits a Message Access Probe (MAP) conditioned on:
– observed Ec/Io > T_rqst dB
– “current” persistence parameters and non-blocking condition
• Mobile uses persistence parameters to regulate access attempts
• After initial MAP, mobile monitors both F-CPCCH and F-CACH:– Closed loop power control begins after parameterized delay value
– Mobile looks for Channel Assignment Message containing its hash ID as confirmation of acquisition
• Conditions:– If no Channel Assn. Message within time-out, mobile ceases transmission of current MAP
and retransmits MAP at higher power some time later
– If wait message sent, cease and reretransmit MAP later
– Stop transmission if either:
» Ec/Io falls below T_fade for T1 seconds
» Ec/Io exceeds T_good and Ec/Io of PC bits is below T_bad for L PC bits
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Power Control Access ModePower Control Access Mode
CPCCH
F-CACH
CACH slot = 5 ms.
EACAM
R-EACHslot
R-EACHMessageR-EACH HeaderPreamble
MessageR-EACH HeaderPreamble
EACAM
R-EACH_PC_DELAY
REACH_MAX_DELAY
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Reservation Procedure (no SHO)Reservation Procedure (no SHO)
• Mobile “randomly” selects a R-EACH and transmits a Enhanced Access Probe (EAP) conditioned on:
– observed Ec/Io > T_rqst dB
– “current” persistence parameters and non-blocking condition
• Mobile uses persistence parameters to regulate access attempts
• After initial EAP, mobile monitors corresponding F-CACH for:– Early Ack. And Channel Assignment Message (EACAM) or Wait Message
• Conditions:– If no message within time-out, retransmit EAP at higher power
– If wait message sent, retransmit EAP later
– If channel assignment rcvd., transmit message on assigned R-CCCH at next access slot and begin closed loop power control.
– Stop transmission if either:
» Ec/Io falls below T_fade for T1 seconds
» Ec/Io exceeds T_good and Ec/Io of PC bits is below T_bad for L PC bits
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Reservation Access Mode (no SHO)Reservation Access Mode (no SHO)
R-EACH Header
CHANNEL ASSN.
MESSAGE
F-CACH
R-EACH
R-CCCH
CPCCH
PRMBL
MSGPRMBL
F-CACH slotR -EAC H
slot
RAC H_PC _DELAY
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RsMA Procedure (SHO)RsMA Procedure (SHO)
• Mobile “randomly” selects a R-EACH and transmits a Enhanced Access Probe (EAP) conditioned on:
– observed Ec/Io > T_rqst dB
– “current” persistence parameters and non-blocking condition
• Mobile uses persistence parameters to regulate access attempts
• After initial EAP, mobile monitors corresponding F-CCCH / F-CACH for:– EACAM Power Control Channel Assignment Message (PCCAM) to get Common PC channel
and sub-channel corresponding to the neighbor BS
• Conditions:– If no PCCAM message within time-out, retransmit EAP at higher power
– If PCCAM rcvd., transmit message on assigned R-CCCH at next access slot and begin closed loop power control using F-CPCCH subchannels indicated in PCCAM.
– Stop transmission if either:
» Ec/Io falls below T_fade for T1 seconds
» Ec/Io exceeds T_good and Ec/Io of both PC bit streams falls below T_bad for L PC bits
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RsMA Mode (w/SHO)RsMA Mode (w/SHO)
EACAM
MESSAGE
F-CCCH
R-EACH
R-CCCH
CPCCH_1
CPCCH_2
PCCAM
R-EACHHeaderPRMBL
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System ProceduresSystem Procedures
• System monitors R-EACH’s for messages & requests on R-EACH slot boundaries
• Basic Access Mode:– If EAP detected on R-EACH, system:
» demodulates and decodes message
» send ACK back on F-CCCH
• PCA Mode:– If MAP detected on R-EACH, system:
» begins closed loop power control,
» queue’s channel assignment message,
» transmits the message in the assigned F-CACH slot(s).
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System Procedures (cont.)System Procedures (cont.)• Reservation Mode:
– If EAP detected on R-EACH, system:
» queue’s channel assignment/access control message,
» transmits the EACAM message on F-CACH
– If no SHO request-->EACAM:
» system monitors the assigned R-CCCH for channel estimation preamble
» If preamble detected system demodulates and power controls message portion
» Else if preamble not detected system releases R-CCCH for subsequent requests and ceases sending PC bits on F-CPCCH after timeout
– If SHO request -->PCCAM
» system exchanges data with neighbor cell
» If any base stations detect preamble, start transmitting closed loop PC bits on assigned F-CPCCH sub-channel
» PCCAM sent on F-CCCH with F-CPCCH info for the neighbor BS.
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AcronymsAcronyms• ACH: Access Channel
• CCCH: Common Control
• DCCH: Dedicated Control Channel
• DCR: Dedicated/Common Router
• DTX: Discontinuous Transmission
• EACAM: Early Ack & Channel Assignment Msg.
• EAP: Enhanced Access Probe
• FCH: Fundamental Channel
• LAC: Link Access Control
• MAC: Medium Access Control
• MAP: Message Access Probe
• PLIDF: Physical Layer Dependent Function
• RBP: Radio Burst Protocol
• RC: Resource Control
• RLP: Radio Link Protocol
• SCH: Supplemental Channel
• PCA: Power Control Access
• PCCAM: Power Control & Channel Assignment Msg.
• PCH: Paging Channel• PICH: Pilot Channel • PLICF: Physical Layer Independent
Convergence Function