Radio & MS-PCUSN Interfaces

7/30/2019 Radio & MS-PCUSN Interfaces

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RADIO & MS-PCUSNINTERFACES

RADIO & MSRADIO & MSRADIO & MS---PCUSNPCUSNPCUSN

INTERFACESINTERFACESINTERFACES

KARI HEIKKILAKARI HEIKKILA

MUHAMMAD ALIMUHAMMAD ALI

OVERVIEWOVERVIEWOVERVIEW

!! The chapter focus on radio interfaces:The chapter focus on radio interfaces:

!! Interface between Mobile Station (MS) and BaseInterface between Mobile Station (MS) and Base

Transceiver Station (BTS)Transceiver Station (BTS)

!! Interface between Mobile Station (MS) and PacketInterface between Mobile Station (MS) and Packet

Control Unit (PCU)Control Unit (PCU)


2/17

RLC/MAC & RF LAYERSRLC/MAC & RF LAYERSRLC/MAC & RF LAYERS

GSM RF

IP/X.25

SNDCP

LLC

RLC

MAC

Application

L1 bis

SNDCP

LLC

BSSGR

NS

L1

RLC

MAC

L1 bis

BSSGR

NS

GSM RF L1

MS PCUBTS SGSN

LLC Relay

IP/X.25 Relay

UmGbAbis,

Agprs

MSMSMS---BTS INTERFACEBTS INTERFACEBTS INTERFACE

!! Corresponds to GSM RF layer:Corresponds to GSM RF layer:

!! Physical RF LayerPhysical RF Layer

!! Modulation and DemodulationModulation and Demodulation

!! Physical Link LayerPhysical Link Layer

!! ChannelChannel--coding functionscoding functions

!! InterleavingInterleaving

!! Radio channel measurement functionsRadio channel measurement functions

!! Radio management proceduresRadio management procedures


3/17

PACKET LOGICAL CHANNELSPACKET LOGICAL CHANNELSPACKET LOGICAL CHANNELS

!! GPRS uses some GSM broadcast channels forGPRS uses some GSM broadcast channels for

!! Frequency tuningFrequency tuning

!! SynchronizationSynchronization

!! For other purpose new packet logical channelsFor other purpose new packet logical channels

are definedare defined

!! Carried by packetCarried by packet--switched channelswitched channel

!! Packet Data Channels (PDCH)Packet Data Channels (PDCH)

PACKET LOGICAL CHANNELSPACKET LOGICAL CHANNELSPACKET LOGICAL CHANNELS

Logical Channels

BroadcastChannels

Common Channels Dedicated Channels

CommonControl

Channels

PBCCH

TrafficChannels

PPCH PNCH

PRACH PAGCH

CommonControl

Channels

PACCH

PTCCH

PDTCH

Broadcast ResourceAssignment

AccessGrant

Notification

RandomAccess

Paging

TimingAdvance

DataTraffic


4/17

PDCH ALLOCATIONPDCH ALLOCATIONPDCH ALLOCATION

!! Different time slots are reserved:Different time slots are reserved:

!! GSM systemGSM system

!! GPRS systemGPRS system

!! Mix of the two on first come first serve basisMix of the two on first come first serve basis

!! In future GPRS phases will likely to haveIn future GPRS phases will likely to have

dynamic time slot configuration based on thedynamic time slot configuration based on the

capacitycapacity--onon--demand principledemand principle

!! PDCH share same physical resource as circuitPDCH share same physical resource as circuit--

switched servicesswitched services

PDCH ALLOCATIONPDCH ALLOCATIONPDCH ALLOCATION

!! At least one PDCH is a master channel carryingAt least one PDCH is a master channel carrying

!! PCCHPCCH

!!

PDTCHPDTCH!! PACCHPACCH

!! Other act as slave channelsOther act as slave channels

!! Possible configurationsPossible configurations

!! PDTCHPDTCH

!! PCCCH + PDTCHPCCCH + PDTCH

!! PBCCH + PCCCHPBCCH + PCCCH

!!

PBCCH + PCCCH + PDTCHPBCCH + PCCCH + PDTCH


5/17

MULTIFRAME STRUCTUREMULTIFRAME STRUCTUREMULTIFRAME STRUCTURE

!! Packet channel carriesPacket channel carries

!! RLC data blocksRLC data blocks

!! RLC/MAC control blocksRLC/MAC control blocks

!! The multiframe structure for PDCH consists ofThe multiframe structure for PDCH consists of

!! 52 successive TDMA frames52 successive TDMA frames

!! 12 blocks12 blocks 4 frames4 frames

!! Multiplexing is not fixedMultiplexing is not fixed

!! Managed by some parameters and block orderManaged by some parameters and block order

!! 4 idle frames4 idle frames

!! Signal measurementsSignal measurements

!! Base Station Identity CodeBase Station Identity Code

SI 13SI 13SI 13

!! If PBCCH is present SI 13 indicates:If PBCCH is present SI 13 indicates:

!! Channel description for the PBCCHChannel description for the PBCCH

!! TN (Time Slot Number for PBCCH andTN (Time Slot Number for PBCCH and PCCCHsPCCCHs))

!! TSC (Training Sequence Code for PBCCH and correspondingTSC (Training Sequence Code for PBCCH and corresponding

PCCCH)PCCCH)

!! ARFCN (Nonhopping radio frequency Absolute RF ChannelARFCN (Nonhopping radio frequency Absolute RF Channel

Number)Number)

!! Localization of PSI type 1 informationLocalization of PSI type 1 information

!! If PBCCH is not present SI 13 indicates:If PBCCH is not present SI 13 indicates:

!! RAC (Routing Area Code)RAC (Routing Area Code)


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NETWORK CONTROLNETWORK CONTROLNETWORK CONTROL

!! Valid parametersValid parameters

!! NETWORK_CONTROL ORDERNETWORK_CONTROL ORDER

!! Valid in packet transfer modeValid in packet transfer mode

!! Can be sent individually to MSCan be sent individually to MS

!! REPORTING_PERIODREPORTING_PERIOD

!! Valid in packet idle modeValid in packet idle mode

!! The interval time between the measurementThe interval time between the measurement

NETWORK CONTROLNETWORK CONTROLNETWORK CONTROL

!! Possible actions to order to MSPossible actions to order to MS

!! NC0 (Normal MS control)NC0 (Normal MS control)

!! MS performs autonomous cell reselectionMS performs autonomous cell reselection

!! NC1 (MS control with measurement reports)NC1 (MS control with measurement reports)

!! MS sends measurement reports to networkMS sends measurement reports to network

!! MS performs autonomous cell reselectionMS performs autonomous cell reselection

!! NC2 (Network control)NC2 (Network control)

!! MS sends measurement reports to networkMS sends measurement reports to network

!! MS canMS cant performs autonomous cell reselectiont performs autonomous cell reselection


7/17

DECODING OF PDCHDECODING OF PDCHDECODING OF PDCH

CONFIGURATIONCONFIGURATIONCONFIGURATION

!! PBCCH DESCRIPTIONPBCCH DESCRIPTION

!! MS decodes BCCH on SI 13MS decodes BCCH on SI 13!! Gets GPRS relevant parametersGets GPRS relevant parameters

!! If PCCCH is usedIf PCCCH is used!! PCCCH description is sent on SI 13PCCCH description is sent on SI 13

!! Indicates that PDCH is carrying PBCCHIndicates that PDCH is carrying PBCCH

!! PBCCH carries information about neighboring cellsPBCCH carries information about neighboring cells

!! If PCCCH is not usedIf PCCCH is not used!! GPRS information is transmitted on BCCH SI 13GPRS information is transmitted on BCCH SI 13

!! PBCCH first block (B0) decodingPBCCH first block (B0) decoding

!! Shows how many PBCCH blocks are useShows how many PBCCH blocks are use

!! Packet System Information DecodingPacket System Information Decoding

ONEONEONE---PHASE & TWOPHASE & TWOPHASE & TWO---PHASE ACCESSPHASE ACCESSPHASE ACCESS

MS

Mandatory for2 phase access

Stops here if 1-phaseor short access

PRACH (or RACH)

PAGCH (or AGCH)

PACCH

PACCH

PacketChannelRequest

PacketResourceRequest

PacketImmediate

Assignment

PacketResourceA

ssignment


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STATIC UPLINK ALLOCATIONSTATIC UPLINK ALLOCATIONSTATIC UPLINK ALLOCATION

!! Can be allocated in following waysCan be allocated in following ways

!! From 1 to 8 time slots on the same TDMAFrom 1 to 8 time slots on the same TDMA

!! By indicating the position of the first block to use as aBy indicating the position of the first block to use as a

TDMA numberTDMA number

!! By a DL control time slotBy a DL control time slot

!! By a bitmap, indicating the specific blocks dedicatedBy a bitmap, indicating the specific blocks dedicated

to the mobile station on each time slot of the TDMAto the mobile station on each time slot of the TDMA

DYNAMIC UPLINK ALLOCATIONDYNAMIC UPLINK ALLOCATIONDYNAMIC UPLINK ALLOCATION

!! Bitmap is not transmitted for UL accessBitmap is not transmitted for UL access

!! Uplink State Flag (USF) coded onto 3 bits isUplink State Flag (USF) coded onto 3 bits is

attribute to each MSattribute to each MS


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RLC/MAC BLOCK STRUCTURERLC/MAC BLOCK STRUCTURERLC/MAC BLOCK STRUCTURE

RLC HeaderOptional

R

TI

Length Indicator M E

TFI = 5 BITS

BSN = 7 BITS E


RLC Data

PayloadType MAC Header

Uplink RLC data block

TLLI

Spare

CountdownValue SI

Optional

RRB USF

FBI


PR TFI = 5 BITS

BSN = 7 BITS E


RLC Data

PayloadType

RLC Header

MAC Header

Downlink RLC data block

S/P

MAC HEADERMAC HEADERMAC HEADER

!! Uplink State Flag (USFUplink State Flag (USF 3 bits)3 bits)

!! Identify user for UL transmissionIdentify user for UL transmission

!! Or characterize a Packet Random Access channel (PRACH)Or characterize a Packet Random Access channel (PRACH)

!! Type (2 bits)Type (2 bits)!! RLC data blockRLC data block

!! RLC/MAC control blockRLC/MAC control block

!! Polling Control (3 bits)Polling Control (3 bits)

!! One supplementary/Polling (S/P) bit to poll MSOne supplementary/Polling (S/P) bit to poll MS

!! Two Relative Reserved Block Period (RRBP) bits to tell MSTwo Relative Reserved Block Period (RRBP) bits to tell MS

where to send acknowledgment messagewhere to send acknowledgment message


10/17

RLC DATA BLOCK HEADERRLC DATA BLOCK HEADERRLC DATA BLOCK HEADER

!! Block Sequence Number (BSNBlock Sequence Number (BSN 7 bits)7 bits)

!! Carries the absolute BSN modulo 128 of each RLC data block withiCarries the absolute BSN modulo 128 of each RLC data block withinnthe TBFthe TBF

!! Temporary Flow Identifier (TFITemporary Flow Identifier (TFI 5 bits)5 bits)

!! Identifies the TBF toIdentifies the TBF to wichwich the RLC block belongsthe RLC block belongs

!! Power Reduction (PRPower Reduction (PR 2 bits)2 bits)

!! Indicates power level reduction of the next RLCIndicates power level reduction of the next RLC

!! Final Block Identifier (FBIFinal Block Identifier (FBI 1 bit)1 bit)

!! Indicates the last blockIndicates the last block

!! Length Indicator (optional bytes)Length Indicator (optional bytes)

!! Delimit the LLC frames when RLC block contains more than one LLCDelimit the LLC frames when RLC block contains more than one LLCframeframe

!! Temporary Logical Link Identifier (TLLITemporary Logical Link Identifier (TLLI several bytes)several bytes)

!! Identifies the logical link between user and Serving GPRS SupporIdentifies the logical link between user and Serving GPRS SupporttNode (SGSN)Node (SGSN)

DL RESOURCE ALLOCATIONDL RESOURCE ALLOCATIONDL RESOURCE ALLOCATION

MS is standby

MS

Ready

PPCH (or PCH)

PAGCH (or AGCH)

PacketChannelRequest

PacketPagingReq

uest

PacketImmediateA

ssignment

PacketPagingResponse

PacketImmediate

Assignment

ARFCN,TS,TFI

ARFCN,TS,TBFst

artingtime,TAI

PacketControlAcknowledgement

Standby

PRACH (or RACH)

PDTCH

MS is ready

PAGCH (or AGCH)PDTCH

PDTCH

TFI differentiates 2 MSReceiving blocks on

the same PDCH


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RLC/MAC BLOCKRLC/MAC BLOCKRLC/MAC BLOCK

!! NLNL--PDU are transmitted using LLC and RLC/MACPDU are transmitted using LLC and RLC/MAC

!! SubnetworkSubnetwork--Dependent Convergence ProtocolDependent Convergence Protocol

transforms packets into LLC framestransforms packets into LLC frames

!! LLC frames are then segmented into RLC/MAC controlLLC frames are then segmented into RLC/MAC control

blocksblocks

ACTIVITY AT THE BSSACTIVITY AT THE BSSACTIVITY AT THE BSS

!! BSS GPRS Protocol (BSSGP) separateBSS GPRS Protocol (BSSGP) separate

!! LLC framesLLC frames

!!

GPRS mobility management informationGPRS mobility management information!! Network management informationNetwork management information


12/17

MAC LAYERMAC LAYERMAC LAYER

!! Allow multiple MS to share common mediumAllow multiple MS to share common medium!! In UL plays the role of an arbitratorIn UL plays the role of an arbitrator

!! In DL aids queuing and schedulingIn DL aids queuing and scheduling

!! Prioritizes the data to be sentPrioritizes the data to be sent

!! Key IdentifiersKey Identifiers!! Temporary Block Flow (TBF)Temporary Block Flow (TBF)

!! Temporary Flow Identity (TFI)Temporary Flow Identity (TFI)

!! Data Burst 1Data Burst 1

!! IdleIdle

!! Data Burst 2Data Burst 2

MAC LAYERMAC LAYERMAC LAYER

!! Channel allocationChannel allocation

!! Fixed allocationFixed allocation

!! Use a fixed channels for transfer of dataUse a fixed channels for transfer of data

!! Dynamic allocationDynamic allocation

!! Use USFUse USF

!! Extended dynamic allocationExtended dynamic allocation

!! A range of channels can be specifiedA range of channels can be specified


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RLC/MAC BLOCK STRUCTURERLC/MAC BLOCK STRUCTURERLC/MAC BLOCK STRUCTURE

UplinkPayloadType

CountdownValue SI R

126 5 4 38 7

S/PPayloadType RRBP USF

126 5 4 38 7

Downlink

!! Uplink State Flag (USF)Uplink State Flag (USF)

!! Supplementary/Polling bit (S/P)Supplementary/Polling bit (S/P)

!! Relative Reserved Block Period (RRBP)Relative Reserved Block Period (RRBP)

!! Stall Indicator (SI)Stall Indicator (SI)

!!

Retry bit (R)Retry bit (R)

RLC LAYERRLC LAYERRLC LAYER

!! Segmentation and reassembling of dataSegmentation and reassembling of data

!! Support two modes of operationSupport two modes of operation!!

AcknowledgedAcknowledged!! Enables selective retransmissionEnables selective retransmission

!! UnacknowledgedUnacknowledged

!! Important in applications that require constant delayImportant in applications that require constant delay


14/17

BSS GPRS PROTOCOL LAYERBSS GPRS PROTOCOL LAYERBSS GPRS PROTOCOL LAYER

!! Provides link for data transfer b/w BSSGP andProvides link for data transfer b/w BSSGP and

SGSNSGSN

!! UnconfirmedUnconfirmed

!! ConnectionlessConnectionless

!! Receive information from Frame RelayReceive information from Frame Relay

!! Controls seveControls several MSral MS

!! Provides radioProvides radio--related QoSrelated QoS

!! Routing informationRouting information

CHANNEL CODINGCHANNEL CODINGCHANNEL CODING

!! Block codeBlock code!! Defined in GSM Recommendations 05.30Defined in GSM Recommendations 05.30

!! Receives input block of 240 bits and adds 4 zero tailReceives input block of 240 bits and adds 4 zero tailbitsbits

!! The output block is 244 bitsThe output block is 244 bits

!! Convolutional codeConvolutional code!! Add redundancy bitsAdd redundancy bits

!! Convolutional encoder contains memoryConvolutional encoder contains memory

!! A block of 488 bits is generatedA block of 488 bits is generated

!! This block is punctured to produce block or 456 bitsThis block is punctured to produce block or 456 bits


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!! Coding SchemeCoding Scheme--1 (CS1 (CS--1)1)

USF Headers and Data USF

3 181 40 = 224 bits

4 tail bitsrate

Convolutionalcoding

6

456




6 268 16 = 290 bits

4 tail bitsrate

Convolutionalcoding

12

588 bits

Puncturing(132 bits)

294 bits

456 bits


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!!

Coding SchemeCoding Scheme--3 (CS3 (CS--3)3)


6 312 16 = 334 bits

4 tail bitsrate

Convolutionalcoding

12

676 bits

Puncturing(220 bits)

338 bits

456 bits




3 428 16 = 447 bits

Nocoding

12

456

Pre-coding


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RLC LAYER SEGMENTATIONRLC LAYER SEGMENTATIONRLC LAYER SEGMENTATION

!! LLC frames are variable in length and RLC/MACLLC frames are variable in length and RLC/MAC

blocks are fixed in lengthblocks are fixed in length

!! One LLC frame may spread onto several RLC/MACOne LLC frame may spread onto several RLC/MAC

blocksblocks

!! One RLC/MAC block may carry several LLC framesOne RLC/MAC block may carry several LLC frames

QUALITY OF SERVICE (QoS)QUALITY OF SERVICE (QoS)QUALITY OF SERVICE (QoS)

!! A QoS profile is associated with each PDPA QoS profile is associated with each PDP

context and is considered a single parametercontext and is considered a single parameter

with multiple data transfer attributeswith multiple data transfer attributes!! Precedence classPrecedence class

!! Delay classDelay class

!! Reliability classReliability class

!! Peak throughput classPeak throughput class

!! Mean throughput classMean throughput class

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Radio & MS-PCUSN Interfaces