Section 4: cdma2000 MAC Overview 1 Section 4: cdma2000 MAC Section 4: cdma2000 MAC.

Section 4: cdma2000 MAC Overview

1

Section 4:Section 4:

cdma2000 MACcdma2000 MAC


2

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


3

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


4

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.


5

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


6

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


7

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.


8

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;


using the ctch

Dorm antIdle

Dorm antBurst

Dorm antIdle

States

T active


m onitoring com m onchannels


9

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 )


10

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


11

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)



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


12

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)


13

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


14

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


15

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


16

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


17

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


18

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


19

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


20

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


21

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


22

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


23

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 '


24

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


25

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 '


26

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.


27

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


28

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)


29

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


30

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.)


31

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


32

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


33

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)


34

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


35

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


36

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)


37

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



• 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.


38

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


39

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


40

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


41

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


42

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


43

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


44

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


45

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


46

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


47

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


48

Reservation Procedure (no SHO)Reservation Procedure (no SHO)

• Mobile “randomly” selects a R-EACH and transmits a Enhanced Access Probe (EAP) conditioned on:




• 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.



» Ec/Io exceeds T_good and Ec/Io of PC bits is below T_bad for L PC bits


49

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


50

RsMA Procedure (SHO)RsMA Procedure (SHO)

• Mobile “randomly” selects a R-EACH and transmits a Enhanced Access Probe (EAP) conditioned on:




• 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.



» Ec/Io exceeds T_good and Ec/Io of both PC bit streams falls below T_bad for L PC bits


51

RsMA Mode (w/SHO)RsMA Mode (w/SHO)

EACAM

MESSAGE

F-CCCH

R-EACH

R-CCCH

CPCCH_1

CPCCH_2

PCCAM

R-EACHHeaderPRMBL


52

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).


53

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.


54

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

Section 4: cdma2000 MAC Overview 1 Section 4: cdma2000 MAC Section 4: cdma2000 MAC.

Documents

Transcript of Section 4: cdma2000 MAC Overview 1 Section 4: cdma2000 MAC Section 4: cdma2000 MAC.