e Gprs Workshop Orlando 1

1 © NOKIA Presentation_Name.PPT / DD-MM-YYYY / Initials Company Confidential

GPRS Radio Planning


GPRS Air Interface Structure


Data Transfer - Temporary Block Flow (1)

A Temporary Block Flow (TBF):• is a one-way session for packet data transfer between MS and BSC (PCU)• uses either uplink or downlink but not both (except for associated

signaling)• can use one or more TSLs

Compare with circuit-switched:• normally one connection uses both the uplink and the downlink

timeslot(s) for traffic

In two-way data transfer:• uplink and downlink data are sent in separate TBFs - as below

BSCBSC

Uplink TBF (+ PACCH for downlink TBF)

Downlink TBF (+ PACCH for uplink TBF)

PACCH (Packet Associated Control Channel): Similar to GSM CSW SACCH


Data Transfer - Temporary Block Flow (2)

Uplink data

Signalling

Uplink TBF

Downlink data

SignallingDownlink TBF

Downlink data

Uplink dataSimultaneousDownlink TBFand Uplink TBF


Establishing an UL TBF and Sending Data

Packet Channel Request

Immediate Assignment for UL TBF

UL Data

Signaling + Ack/Nack

BTSBTS

Final UL Data

Final Ack/Nack

Packet control Ack

RACH

AGCH

PDTCH

PACCH

PDTCH

PACCH

PACCH


Establishing a DL TBF and Sending DataPaging

UL TBF forMS location

Packet Control Ack (for TA)

Packet Polling

Packet Downlink Assignment

Data / Signalling

Ack / Nack

Packet Channel Request

Packet Paging Response (LLC Frame)

BTSBTS

RACH

AGCH

PDTCH

PACCH

PACCH

PACCH

PCH

Immediate Assignment for UL TBF

Immediate Assignment for DL TBF AGCH

PDTCH

PACCH

PACCH


SGSNMS BSS

Um Gb

MS-SGSN Protocol layers

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF

RLC

MAC

GSM RF

LLC

SNDCP

BSSGP

NW sr

L1bis

BSSGP

NW sr

L1bis


SNDCP (Subnetwork Dependent Convergence Protocol) Layer

• Multiplexer/demultiplexer for different network layer entities onto LLC layer

• Compression of protocol control information (e.g. TCP/IP header)

• Compression of data content (if used)

• Segmentation/de-segmentation of data to/from LLC layer

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF


Logical Link Control (LLC) Layer

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF

• Reliable logical connection between SGSN and MS

• Independent of underlying radio interface protocols

ControlAddress

FCSInformation

LLC Frame

1 1-3 140-1520 3 Octets


Radio Link Control (RLC)/ Medium Access Control (MAC) Layers

RLC

• Reliable transmission of data across air interface

• Segmentation/de-segmentation of data from/to LLC layer

MAC

• Control of MS access to common air-interface medium

• Flagging of PDTCH/PACCH occupancy

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF


Downlink RLC data block with MAC header

USF - Uplink State Flag

TFI - Temporary Flow Indicator (TBF ID)

FBI - Final Block Indicator

BSN - Block Sequence Number (RLC Block ID within TBF)

Bit8 7 6 5 4 3 2 1

Payload Type RRBP S/P USF MAC headerPR TFI FBI Octet 1

BSN E Octet 2Length indicator M E Octet 3 (optional)

.

.

.

.

.

.Length indicator M E Octet M (optional)

Octet M+1

RLC data.

.

.Octet N2-1Octet N2

spare spare (if present)


Bit8 7 6 5 4 3 2 1

Payload Type Countdown Value SI R MAC headerspare PI TFI TI Octet 1

BSN E Octet 2Length indicator M E Octet 3 (optional)

.

.

.

.

.

.Length indicator M E Octet M (optional)

Octet M+1 \TLLI Octet M+2 } (optional)

Octet M+3 /Octet M+4 /

PFI E Octet M + 5 /Octet M+6

RLC data...Octet N-1Octet N

spare spare (if present)

Uplink RLC data block with MAC header

Countdown Value - Used to calculate number of RLC blocks remaining(SGSN Function)

TLLI - Temporary Logical Link Identifier (type of mobile ID)


• Several mobiles can share one timeslot

• Maximum of 9 Mobiles are queued in the downlink

• Temporary Flow Indicator value included in the RLC block header - indicates the associated TBF

• Timeslot selected to give maximum throughput

• Each mobile gets 1 / (no. of MS in queue) of the channels capacity (release 1)

Multiple Mobiles and Downlink Transmission

TS 1

TS 2

TS 3

Multislot Mobile

Temporary Flow Indicator

New MS


Multiple Mobiles and Downlink Transmission

TFI2

TFI5

TFI3

TFI2

MSs

BTS

The TFI included in the Downlink RLC Block header indicates which Mobile will open

the RLC Block associated with its TBF

RLC Data Block


• Several mobiles can share one timeslot

• Maximum of 7 Mobiles are queued in the Uplink

• Mobile transmissions controlled by USF (Uplink State Flag) sent on DL (dynamic allocation)

TS 1

TS 2

TS 3

Uplink State Flag

• Mobile with correct USF will transmit in following Uplink block

• Timeslot selected to give maximum throughput

• Each mobile gets 1 / (no. of MS in queue) of the channels capacity (release 1)

New MS

Multiple Mobiles and Uplink Transmission


Multiple Mobiles and Uplink Transmission

USF = 1

USF = 2

USF = 3

USF = 3

MSs

BTS

RLC Data Block

The USF included in the Downlink RLC Block header identifies which Mobile will

transmit in the following Uplink RLC Block


GSM RF Layer

• Modulation/demodulation

• Bit inter-leaving

• TDMA frame formatting

• Cell selection/re-selection

• Tx power control

• Discontinuous reception (DRx)

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF


Data Block Format

LLC

SNDCP

IP

RLC

MAC

GSM RF

N-PDU (GTP Tunnel)

SN-DATA PDUs(SubNet MUX)

LLC Frames (SGSN ->BSC PCU, includes Ciphering)

RLC Blocks (Dataand PDP Context)

RLC/MAC Blocks

TDMA Bursts


Bursts on the Air Interface

0 7

TDMA frame = 4.615 ms

= BURST PERIOD

0 70 70 7

RLC/MAC Blocks

TDMA Bursts

RLC Blocks

4 x TDMA Frames = 4 Bursts = 1RLC block ~ 20 ms


RLC / LLC Retransmissions

SGSN LLC Frame Retransmissions(MS - SGSN)

• Retransmission of lost/corrupted frames between the BSC/PCU and the SGSN over the Gb interface

Gb

BSC PCU

RLC Block Retransmissions(MS - BSC)

• Retransmission of bad blocks - lost/corrupted

• Proprietary Ack/Nack process

• Used to calculate the BLER and therefore link adaptation

BTS


3

3

1

3

1

1

IncrementRLC data block retransmission

New RLC data Block

RLC data block with poll

PCU

Packet Downlink ACK/NACK

Tim

e

RLC Retransmission Algorithm - Downlink

1010111……...111101001 Bitmap

SSN

MS

XXX

Hardcoded value X

3

6

91011

Total

.

.

.

.

.

.


RLC Retransmission Algorithm - Uplink

3

1

3

1

1

1

1

1

Increment

RLC data transmission

Packet Uplink ACK/NACK

USF

TimePCU

MS

1010111……...111101001Bitmap

SSN

Packet Control ACK/NACK

X

X

1

4

5

69

Total

Hardcoded value Y


Acknowledgement Process

The acknowledgement process is dynamic and based on radio conditions:

• In poor radio conditions the polling rate between the network and mobile will increase improving the reliability.

• In ideal radio conditions the polling is less frequent allowing more data to be sent in place of signaling.

• The dynamic process is based on simulations.


GPRS Data Transfer Throughput


Coding Scheme

Payload (bits)per RLC block

Data Rate (kbit/s)

CS1 181 9.05

CS2 268 13.4

CS3 312 15.6

(No FEC) CS4 428 21.4

More Data =

Less Error Correction

Nokia GPRSRelease 1

CS1 & CS2

- Implemented in ALL Nokia BTS without HW change

CS3 & CS4

- Will not fit in normal 16 kbps Abis TRAU frame.

- Feature Candidate for future releases.

Dat

a

Err

orC

orre

ctio

n

GPRS Coding Schemes


Coding Schemes

USF Header & Data BCS

1/2 rate convolutional

coding

USF- Uplink State Flag

BCS - Block Check Sequence

3 181 + 4 tail bits 40 228 bits

6 456 bits

CS-1

181bits/20ms = 9.05kbit/s


Coding SchemesCS-2

USF Header & Data BCS

1/2 rate convolutional

coding

6 268 + 4 Tail Bits 16 294 bits

12 588 bits

Puncturing (132 bits)

456 bits12

268 bits/20ms = 13.4kbit/s


0

5

10

15

20

25

4 6 8 10 12 14 16 18 20 22 24 26 28 30

C / I ( dB )

Us

er

Dat

a T

hro

ug

hp

ut

(Kb

it/s

)

C S - 1

C S - 2

C S - 3

C S - 4

Impact of C/I on GPRS Throughput(Frequency Hopping Case, TU3 FH)

• CS1 achieves higher user throughput when radio conditions are poor (<6.5dB C/I)

• Link adaptation ensures highest user data rate in Frequency Hopping networks

LA followsCS1 & CS2"Envelope"


Link Adaptation

• Call starts with coding scheme 2

• Link Adaptation algorithm is used to select the optimum coding scheme

• The coding scheme will change based on the BLER

• Retransmissions always occur with the same coding scheme

• CS selection can use link adaptation (LA), or can be fixed (using PRFILE parameters) to either CS-1 or CS-2 at all times.

BLERabove the crosspoint

BLER ok

RLCCS1

CS2RLC

CS2RLC

CS2RLC

BLERunder the crosspoint

CS2CS2

CS1CS1

CS2CS2

CS2CS2



EGPRS Implementation


Content

• Vocabulary

• (E)GPRS Parameters and counters

• 8-PSK modulation concept

• radio interface and RLC block structure

• List of specs


EGPRS Vocabulary 1/7• Block period (BP): A block period is the sequence of four

timeslots on a PDCH used to convey one radio block (20 msec).

• C1: Pathloss criteria for cell re-selection

• C2: Cell re-selection parameter for cell re-selection

• C31: Signal level threshold criterion parameter for hierarchical cell structures (HCS)

• C32: Cell ranking criterion parameter

• Dual transfer mode: In dual transfer mode, the mobile station is allocated radio resources providing an RR connection (3GPP TS 04.18) and a Temporary Block Flow on one or more packet data physical channels. The allocation of radio resource for the RR connection and the Temporary Block Flow is co-ordinated by the network in agreement with the capabilities of the mobile station in dual transfer mode.


EGPRS Vocabulary 2/7

• EGPRS: Enhanced GPRS, enables higher data rates through usage of 8PSK modulation in addition to GMSK. EGPRS also enables Incremental Redundancy operation.

• EGPRS TBF mode: refers to a TBF utilising the EGPRS enhancements, e.g. 8PSK modulation and Incremental Redundancy operation.

• GPRS multislot class: The term GPRS multislot class refers to the different mobile station capabilities to transmit and receive on different combinations of multiple PDCHs. The multislot classes are defined in 3GPP TS 05.02. Note that the mobile station may indicate different multislot classes for circuit mode services and for GPRS (see 3GPP TS 04.08). Different multislot class mobile stations are capable of supporting different medium access modes.



• GPRS TBF mode: refers to a TBF not utilising the EGPRS enhancements, e.g. MCS-1 to MCS-9 and Incremental Redundancy operation.

• IR: Incremental redundancy, enables higher data rates through combining information from different transmissions of RLC data blocks when decoding. Also known as Hybrid Type II/III ARQ.

• MCS: Modulation and Coding Scheme.

• Packet flow context: Packet Flow Context (PFC) procedures are described in 3G TS 23.060. A Packet Flow Identifier (PFI) is used to identify a PFC.



• Packet idle mode: In packet idle mode, the mobile station is prepared to transfer LLC PDUs on packet data physical channels. The mobile station is not allocated any radio resource on a packet data physical channel; it listens to the PBCCH and PCCCH or, if those are not provided by the network, to the BCCH and the CCCH;

• Packet transfer mode: In packet transfer mode, the mobile station is prepared to transfer LLC PDUs on packet data physical channels. The mobile station is allocated radio resource on one or more packet data physical channels for the transfer of LLC PDUs.

• Radio block: A radio block is the sequence of four normal bursts carrying one RLC/MAC protocol data units (see 3GPP TS 04.04). (The one exception is a radio block occasionally used on PACCH consisting of a sequence of four access bursts, each carrying a repetition of one short RLC/MAC block.)



• Random values: In a number of places in this Technical Specification, it is mentioned that some value must take a “random” value, in a given range, or more generally with some statistical distribution. For such random values refer to 3GPP TS 04.08.

• RLC/MAC block: A RLC/MAC block is the protocol data unit exchanged between RLC/MAC entities.

• RLC/MAC control block: A RLC/MAC control block is the part of a RLC/MAC block carrying a control message between RLC/MAC entities.

• RR connection: An RR connection is a physical connection established between a mobile station and the network to support the upper layers’ exchange of information flows. An RR connection is maintained and released by the two peer entities.


EGPRS Vocabulary 6/7• RLC data block: A RLC data block is the part of a RLC/MAC block

carrying user data or upper layers’ signalling data.

• TBF abort: The term “abort” as applied to TBF is used when the TBF is abruptly stopped without using the Release of TBF procedures.

• TBF release: The term “release” as applied to TBF is used when the TBF is stopped using one of the Release of TBF procedures.

• Temporary Block Flow (TBF): A Temporary Block Flow (TBF) is a physical connection used by the two RR peer entities to support the unidirectional transfer of LLC PDUs on packet data physical channels.

• Temporary flow identity (TFI): Each TBF is assigned a Temporary Flow Identity (TFI) by the network.

• Timer Expiry: A started timer has run the time specified.



• Timer Restart: A timer that may already be running is stopped and then started again to run the time specified.

• Timer Start: A timer is started to run the time specified.

• Timer Stop: A started timer is stopped and its value is then undefined.

• Uplink State Flag (USF): The Uplink State Flag (USF) is used on PDCH channel(s) to allow multiplexing of uplink Radio blocks from different mobile stations


EGPRS vocabulary

• More information can be found from the following document:

PCU S10 glossary.doc


Medium access modes• Dynamic Allocation, characterised by that the mobile station detecting

an assigned USF value for each assigned PDCH and block or group of four blocks that it is allowed to transmit on that PDCH

• Extended Dynamic Allocation characterised by the mobile station detecting an assigned USF value for any assigned PDCH allowing the mobile station to transmit on that PDCH and all higher numbered assigned PDCHs in the same block or group of four blocks

• Fixed Allocation characterised by fixed allocation of radio blocks and PDCHs in the assignment message without an assigned USF. Fixed Allocation may operate in half duplex mode, characterised by that downlink and uplink TBF are not active at the same time. Half duplex mode is only applicable for multislot classes 19 to 29

• Exclusive Allocation, characterised by the mobile station being granted the exclusive right to transmit on each assigned PDCH for the duration of an uplink TBF. Exclusive allocation is applicable only in dual transfer mode.

Supported by Nokia


(E)GPRS Parameters and counters

Overview on the most relevant parameters and counters

Usage and setting later


(E)GPRS Packet Signalling

• PBCCH available in BSS S10.5 • GPRS and EGPRS will not impact on AGCH and

PCH

• Increased data rates will lead to heavier signalling demand for given traffic occupancy and applications

• (Note - PBCCH traffic is not carried on TRXSIG)

PBCCH/PCCCH

PBCCH PPCH PDTCH PRACH

BCCH/CCCH

Common Channels

PAGCH


PDCH : 52-TDMA multiframe

It follows a 52-frame structure, which consists of 12 blocks of 4 consecutive frames, 2 idle frames and 2 frames used for the PTCCH (timing advance). The PCU controls radio blocks 0 – 11, while the BTS handles the idle frames.

B0 B1 B2 i B3 B4 B5 i B6 B7 B8 i B9 B10 B11 i


BS_PBCCH_BLKS, number of PBCCH blocks per multiframe. Depends on the number of PSIs and repeat period.

BS_PAG_BLKS_RES, number of blocks in addition to BS_PBCCH_BLKS, where paging shall not occur.

BS_PCC_CHANS number of physical channels carrying PCCCHs including the physical channel carrying the PBCCH. FIXED to 1

BS_PRACH_BLKS number of blocks that are fixed allocated for PRACH per multiframe

Mapping of PBCCH/PCCCH DL/UL parameters


PBCCH/PCCCH DL parameters

bsPBCCHBlocksbsPBCCHBlocks (PBB) (PBB)GSM reference: GSM 04.60Level: BTSModification: PBCCH TRX must be lockedRange: 1 to 4 blocksMML default: 3Description: With this parameter you define the amount of blocks allocated to the PBCCH in

themultiframe.Related command(s): EQJ, EQONote: OPTIONAL (GPRS) bsPagingBlocksResbsPagingBlocksRes (PAB) (PAB)GSM reference: GSM 04.60Level : BTSModification: PBCCH TRX must be lockedRange: 0 to 12MML default: 4Description: With this parameter you indicate the number of blocks on each PDCH carrying

thePCCCH per multiframe where neither packet paging nor PBCCH should appear. This numbercorresponds therefore to the number of blocks reserved for PAGCH, PNCH, PDTCH and

PACCH.Related command(s): EQJ, EQONote: OPTIONAL (GPRS)


PBCCH/PCCCH UL parameters

bsPRACHBlocksbsPRACHBlocks (PRB) (PRB)

GSM reference: GSM 04.60Level: BTSModification: PBCCH TRX must be lockedRange: 0 to 12MML default: 6Description: With this parameter you indicate the number of blocks reserved in a fixed

way to thePRACH channel on any PDCH carrying the PCCCH.The parameter is related to bs PBCCH blocks (BSPB) and bs paging blocks reserve

(BSPA).and datachannel.Related command(s): EQJ, EQONote: OPTIONAL (GPRS)


(E)GPRS parameters: cell (re)selection

• C31_HYSTC31_HYST (CHYS) (CHYS)

Flag which indicates if set to Y that the GPRS_CELL_RESELECT_HYSTERESIS shall be applied to the C31 GPRS cell reselection criterion.

• C32_QUALC32_QUAL (QUAL) (QUAL)

Flag indicating an exception rule for GPRS_RESELECT_OFFSET. If the parameter C32_QUAL is set to Y, positive GPRS_RESELECT_OFFSET values shall only be applied to the neighbour cell with the highest received level average value.



c31Hysteresisc31Hysteresis (CHYS) (CHYS)GSM reference: GSM 04.60Modification: OnlineRange: Y/NMML default: NDescription: With this parameter you indicate the GPRS cell reselection criterion.Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality

c32Qualc32Qual (QUAL) (QUAL)GSM reference: GSM 04.60Modification: OnlineRange: Y/NMML default: NDescription: With this parameter you indicate an exception to the rule for GPRS cellreselect offset.Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality)



gprsTemporaryOffsetgprsTemporaryOffset (GTEO) (GTEO)GSM reference: GSM 04.60Modification: OnlineRange: 0 .. 70 dB with a step size of 10 dBMML default: 0 dBDescription: With this parameter you define the negative offset of the C32 reselection

criterion forthe duration of the GPRS penalty time (GPET) after the MS has placed the cell on the list of

thestrongest carriers. It is used by the mobile station as part of its calculation of C32 for the

cellreselection process.Related command(s): EAC, EAM, EAONote: Optional (Gb Interface functionality)

gprsReselectOffsetgprsReselectOffset (GREO) (GREO)GSM reference: GSM 04.60Modification: OnlineRange: -52, -48,..., -12, -10,..., 12, 16, ...,48 (dB)MML default: 0 dBDescription: With this parameter you define the offset of the C32 reselection criterion for aadjacent cell.Related command(s): EAC, EAM, EAONote: Optional (Gb Interface functionality)



gprsPenaltyTimegprsPenaltyTime (GPET) (GPET)GSM reference: GSM 04.60Modification: OnlineRange: 10 .. 320 (s) with a step size of 10 sMML default: 10 sDescription: With this parameter you define the duration for which the GPRS

temporary offset(GTEO) applies.Related command(s): EAC, EAM, EAONote: Optional (Gb Interface functionality)


(E)GPRS Multi BCF (BSS 10083)

Talk Family BTSUltra Site BTS

BTS 1' (sector 1)TRXs(BCCH)



BTS 1 (sector 1)EDGE TRXs



Segment 1

Segment 2

Segment 3

EDGE-capable and non-EDGE-capableTRXs can be combined into one ‘segment’.

Common BCCH/multi BCF functionalityused to distribute traffic between ‘layers’.

Can be used with, e.g., Talk/Ultrasite


(E)GPRS parameters

• multi BCF/common BCCH related parameters

directGPRSaccessBtsdirectGPRSaccessBts (DIRE) (DIRE)

GSM reference : no ref.Level : BTSModification: OnlineRange: -10 to 10 dBmMML default: 0 dBmDescription: With this parameter you define which BTSs in the SEG may be used for

GPRS or EGPRS without signal level measurements. This parameter defines the signal level compared to non BCCH layer offset. When the value of this parameter is higher than the value of the parameter non BCCH layer offset the direct GPRS access to non BCCH layer BTS is applied. This is used in initial channel allocation and reallocation.

Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality)


(E)GPRS parameters

gprsRxLevAccessMingprsRxLevAccessMin (GRXP) (GRXP)

GSM reference: GSM 04.60Level : BTSModification: OnlineRange: -110 dBm to -47 dBmMML default: -105 dBmDescription: With this parameter you define the minimum power level an MS has to

receive beforeit is allowed to access the cell.Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality)

maxGPRScapacitymaxGPRScapacity (CMAX) (CMAX)

GSM reference:No ref.Level: BTSModification:When BTS is locked or GPRS is disabledRange:1 to 100 %MML default:100 %Description: With this parameter you define the maximum number of PSW (packet

switched)channels in a BTS. The value of the CMAX parameter must be higher than or equal to the

value ofthe CDEF parameter. Related command(s):EQV, EQONote:OPTIONAL (Gb Interface functionality)


(E)GPRS parameters

nonBCCHLayerOffsetnonBCCHLayerOffset (NBL) (NBL) GSM reference: No ref.Level: BTS Modification: OnlineRange: -40 to +40 dBmMML default: 0 dBmDescription: With this parameter you define whether the predefined offset margin is

used whenevaluating the signal level of the non BCCH layer.Related command(s): EQM, EQONote: OPTIONAL (Tri-band common BCCH, Multi-BCF)


(E)GPRS parametersgprsNonBCCHRxlevUppergprsNonBCCHRxlevUpper (GPU) (GPU)GSM reference: No refLevel: BTSModification: OnlineRange: -110 to -47 dBmMML default: -95 dBmDescription: With this parameter you define the minimum power level the MS has to receive

toallocate resources from the BTS.The value of this parameter must be higher than or equal to the value of the parameter GPL.Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality)

gprsNonBCCHRxlevLowergprsNonBCCHRxlevLower (GPL) (GPL)GSM reference: No ref.Level: BTSModification: OnlineRange: -110 to -47 dBmMML default: -100 dBmDescription: With this parameter you define the threshold when a reallocation to a better BTSmust be made. BTS with the direct GPRS access BTS option on is selected. If there are no

BTSswith direct GPRS access BTS set to on, the BTS with the lowest non BCCH layer offset is

selected.The value of this parameter must be lower than or equal to the value of the parameter GPU.Related command(s): EQG, EQONote: OPTIONAL (Gb Interface functionality)


(E)GPRS parameters : TBFs/TSL

pcuMaxNoULtbfInCHpcuMaxNoULtbfInCH (MNUL) (MNUL) GSM reference: No ref.Level: BSCModification: OnlineRange: 0 - 7MML default: 7Description: With this parameter you define the maximum number of TBFs

that a radio time slotcan have in average, in a GPRS territory, in the uplink direction.Related command(s): EEQ, EEONote: Optional (Gb Interface functionality)

pcuMaxNopcuMaxNoDDLtbfInCHLtbfInCH (MNDL) (MNDL) GSM reference: No ref.Level: BSCModification: OnlineRange: 0 – 9 0 – 16! MML default: 9 16! Description: With this parameter you define the maximum number of TBFs

that a radio time slotcan have in average, in a GPRS territory, in the downlink direction.Related command(s): EEQ, EEONote: Optional (Gb Interface functionality)


Parameters (E)GPRS QoS

• QoS parametersDHP / DL high priority SSSDHP / DL high priority SSS

Scheduling step size (SSS) for the high priority level in DL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.3, setting lower than DNP.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO

DNP / DL normal priority SSSDNP / DL normal priority SSS

Scheduling step size (SSS) for the normal priority level in DL.PRFILE class 2, bsc_gprs_param_enabledLEVEL:BSCRanging from 1..12 with def.6, setting lower than DLP and higher than

DHP..It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO


Parameters GPRS/EGPRSQoS

DLP / DL low priority SSSDLP / DL low priority SSS

Scheduling step size (SSS) for the low priority level in DL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.12, setting higher than DNP.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO

UP1/ UL priority1 SSSUP1/ UL priority1 SSS The scheduling step size (SSS) for the priority level 1 (highest) in UL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.3, setting higher than UP2.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO



UP2/ UL priority2 SSSUP2/ UL priority2 SSS

The scheduling step size (SSS) for the priority level 2 in UL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.6, setting lower than UP3 and higher than UP1.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO

UP3/ UL priority3 SSSUP3/ UL priority3 SSS

The scheduling step size (SSS) for the priority level 3 in UL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.9, setting lower than UP4 and higher than UP2.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO



UP4/ UL priority4 SSSUP4/ UL priority4 SSSThe scheduling step size (SSS) for the priority level 4 in UL.PRFILE class 2, bsc_gprs_param_enabledLEVEL: BSCRanging from 1..12 with def.12, setting higher than UP3.It can be changed ON-LINE.MML command to modify: EEVMML command to view: EEO


(E)GPRS PRFILE parameters in S10.5The following parameters are related to the Gb interface configuration and state management and the PCU.

Following parameters refer to MAC and RLC protocols (Abis interface):

BSC_GPRS_PARAM_ENABLED FC_MS_B_MAX_DEF_EGPRS

TNS_BLOCK / TNS_RESET/TNS_TEST /TNS_ALIVE FC_MS_R_DEF

NS_BLOCK_RETRIES / NS_UNBLOCK_RETRIES FC_MS_R_DEF_EGPRS

NS_ALIVE_RETRIES FC_MS_R_MIN

NS_RESET_RETRIES FC_R_DIF_TRG_LIMIT

TGB_BLOCK / TGB_RESET /TGB_SUSPEND FC_R_TSL

BVC_BLOCK_RETRIES FC_R_TSL_EGPRS

BVC_UNBLOCK_RETRIES GPRS_DOWNLINK_PENALTY

BVC_RESET_RETRIES GPRS_DOWNLINK_THRESHOLD

SUSPEND_RETRIES GPRS_TBF_REALLC_THRSHLD

BSSGP_FLOW_CONT_ON_LEV GPRS_UPLINK_PENALTY

BSSGP_FLOW_CON_OFF_LEV GPRS_UPLINK_THRESHOLD

BTS_LOAD_REALLC_THRSHLD MEMORY_OUT_FLAG_SUM

BTS_TSL_BALANCE_THRSHLD PRE_EMPTIVE_TRANSMISSIO

EGPRS_DOWNLINK_PENALTY TBF_LOAD_GUARD_THRSHLD

EGPRS_DWNLINK_THRESHOLD TBF_SIGNAL_GRD_THRSHLD

EGPRS_RE_SEGMENTATION TERRIT_BALANCE_THRSHLD

EGPRS_UPLINK_PENALTY TERRIT_UPD_GTIME_GPRS

EGPRS_UPLINK_THRESHOLD UPLNK_RX_LEV_FRG_FACTOR

FC_B_MAX_TSL

FC_B_MAX_TSL_EGPRS

FC_MS_B_MAX_DEF


Parameters EGPRS 1/8

• BTS parameters

EGENA / EGPRS enabledEGENA / EGPRS enabled (comparable with the existing parameter :GENA for GPRS)

Switch-type of BTS level parameter with value “Y” or “N”. In order to be visible the class 2 features BSC_gprs_param_enabled (in PRFILE)

and egprs_usage (in FIFILE) should be available.

GPRS must be enabled in the SEGMENT (GENA=Y for all the BTS in the SEGMENT) in order to enable EGPRS in the BTS.

BTS must be locked in order to modify EGENA from default value N to Y.

MML command to modify: EQV

MML command to view: EQO



• EGPRS Link Adaptation parameters

MCA / initial MCS for acknowledged modeMCA / initial MCS for acknowledged mode (RLC ack’ed) (RLC ack’ed)

MCS used at the beginning of TBF for ack’ed mode

In order to be visible the class 2 features BSC_gprs_param_enabled (in PRFILE) and egprs_usage (in FIFILE) should be available.

SEGMENT level parameter type, ranging from value 1(MCS-1) to value 9(MCS=9) (unit byte). Def. is 9.

Can be set ON-LINE.





MCU / initial MCS for unacknowledged modeMCU / initial MCS for unacknowledged mode (RLC unack’ed)(RLC unack’ed)

MCS used at the beginning of TBF for unack’ed mode


SEGMENT level parameter type, ranging from value 1 to value 9 (unit byte). Def. is 6.

Can be set ON-LINE.





BLA / Max BLER in acknowledged modeBLA / Max BLER in acknowledged mode

Max BLER of first transmission in ack’ed mode.


SEGMENT level parameter type, ranging from 10 to 100 (%) (byte). Def. value is 90 (%).

Can be set ON-LINE.





BLU / Max BLER in unacknowledged modeBLU / Max BLER in unacknowledged mode

Max BLER of first transmission in unack’ed mode


SEGMENT level parameter type, ranging from 1 to 100 (parts per thousand) (byte). Def. value is 10 (=0.01).

Can be set ON-LINE.





MBG / mean Bit Error Probability offset GMSKMBG / mean Bit Error Probability offset GMSK

Offset added to reported GMSK mean BEP values before BEP table look-up (applied both in UL and DL)


SEGMENT level parameter type, ranging from –31..31 in MML, with default 0.

Can be set ON-LINE.





MBP / mean Bit Error Probability offset 8PSKMBP / mean Bit Error Probability offset 8PSK

Offset added to reported 8PSK mean BEP values before BEP table look-up (applied both in UL and DL)


SEGMENT level parameter type, ranging from –31..31 in MML, with default 0.

Can be set ON-LINE.





• Power Control Parameters

BEP / Bit Error probabilty periodBEP / Bit Error probabilty period

BEP filter averaging period for EGPRS channel quality measurements.


SEGMENT level parameter type, ranging from 0..10 (see mapping in MML from dictionary), def. value is 10 (in MML =6).

Can be set ON-LINE.

MML command to modify: EUM

MML command to view: EUO


EGPRS specific counters

• PCU CountersPCU Counters

072088. Number of established uplink EGPRS TBFs072089. Number of established downlink EGPRS TBFs072090. Number of established uplink EGPRS TBFs in unacknowledged

mode072091. Number of established downlink EGPRS TBFs in

unacknowledged mode072092. Number of UL TBF establishment failed072093. Number of DL TBF establishment failed072094. Number of failed uplink EGPRS TBF establishments due to no

response from MS072095. Number of failed uplink EGPRS TBF establishments due to no

response from MS


EGPRS specific counters

• Coding Scheme countersCoding Scheme counters Updated by using BTS identity + MCS coding scheme as object levelUpdated by using BTS identity + MCS coding scheme as object level

079000. Number of DL RLC blocks ack mode079001. Number of DL RLC blocks unack mode079002. Number of UL RLC blocks ack mode079003. Number of UL RLC blocks unack mode079004. Number of bad RLC data blocks with valid header UL unack

mode079005. Number of bad RLC data blocks with bad header UL unack

mode 079006. Number of bad RLC data blocks with valid header UL ack mode079007. Number of bad RLC data blocks with bad header UL ack mode079008. Retransmitted RLC data blocks UL 079009. Retransmitted RLC data blocks DL


EGPRS related specifications 1/2 -Some relevant specs discussing EDGE-

• 3GPP TS 03.60 describes the overall GPRS logical architecture and the GPRS functional layers above the Radio Link Control and Medium Access Control layer.

• 3GPP TS 03.64 contains an overview of the GPRS radio interface (Um).

• 3GPP TS 04.08 contains the definition of GPRS RLC/MAC procedures when operating on the Common Control Channel (CCCH).

• GSM 04.18 specifies the procedures used at the radio interface for Radio Resource (RR) management.

• 3GPP TS 04.60 provides the overall description for RLC/MAC layer functions of the general Packet Radio Service (GPRS and EGPRS) radio interface Um.


EGPRS related specifications 2/2 -Some relevant specs discussing EDGE-

• 3GPP TS 05.02 defines the physical channels of the radio sub‑system required to support the logical channels.

• GSM 05.04 describes the modulation formats for GMSK and 8 PSK.

• 3GPP TS 05.05 defines the requirements for the transceiver of the pan‑European digital cellular telecommunications systems GSM.

• 3GPP TS 05.08 specifies the Radio sub‑system link control implemented in the Mobile Station (MS), Base Station System (BSS) and Mobile Switching Centre (MSC) of the digital cellular telecommunications systems GSM.


Modulation

• GMSK-modulation

• 8-PSK modulation

• Back-off

• Impairments


(0,0,1)

(1,0,1)

(d(3k),d(3k+1),d(3k+2))=

(0,0,0) (0,1,0)

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

New modulation: 8-PSK

EDGE GSM + EDGE Modulation 8-PSK, 3bit/sym GMSK, 1 bit/sym Symbol rate 270.833 ksps 270.833 ksps Bits/burst 348 bits

2*3*58 114 bits 2*57

Gross rate/time slot 69.6 kbps 22.8 kbps

• 8-PSK (Phase Shift Keying) has been selected as the new modulation added in EDGE

• Non-constant envelope high requirements for linearity of the power amplifier

• Because of amplifier non-linearities, a 2-4 dB power decrease (back-off) is typically needed, Nokia guaranteed a BO of 2 DB for BTS

• 3 bits per symbol

• 22.5° offset to avoid origin crossing (called 3/8-8-PSK)

• Symbol rate and burst length identical to those of GMSK

3/8

Phase states transitionsto avoid zero-crossing


GMSK & 8-PSK (1)

22,5° offset to avoid zero crossing

GMSK

8PSK(0,0,1)

(1,0,1)

(0,0,0) (0,1,0)

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

Time

Envelope (amplitude)

Time



8-PSK Tx Power Reduction

GMSK

8PSK

Time


Time


Peak to Average of 3,2 dB

Pin

Pout

BTS Back Off= 2 dB

Compression point


8-PSK Modulation: implicit limitation

• Since the amplitude is changing in 8-PSK the transmitter non linearities can be seen in the transmitted signal

• These non-linearities will cause e.g. errors in reception and bandwidth spreading.

• In practice it is not possible to transmit 8-PSK signal with the same power as in GMSK due to the signal must remain in the linear part of the power amplifier


Impairments• 8-PSK sensitive to distortion in RF hardware - tx/rx impairment

effects (phase noise, non-linearity)

Thro

ughput

kbit

/s

Eb/No

Thro

ughput

kbit

/s

Eb/No

With IRWithout IR


Sources of S/N : impairments

There are many causes of impairments that cause S/N reduction in signal sources.

They group in three categories : Linear, Nonlinear and Miscellaneous.

Among Nonlinear Errors there’s the Amplitude Error caused by amplifier gain variation as a function of signal

amplitude,sometimes called AM/AM conversionand the Phase Error that is phase variations as function of signal amplitude and

sometimes calledAM/PM. Among Miscellaneous Errors is the Phase Noise that is Excessive random variation of the carrier’s phase.

• Phase noise : in an oscillator, rapid, short-term, random fluctuations in the phase of a wave, caused by time-domain instabilities. Note: Phase noise is given in decibels relative to carrier power (dBc) (average unmodulated power) on a 1-Hz bandwidth


EGPRS Radio Interface


EGPRS Radio interface

• Packet data logical channels

• Data transfer principles

• RLC Radio block structure

• Multislot MS

• MCS selection

• Multiplexing GPRS/EGPRS

• Link adaptation


Packet data logical channels 1/2PBCCH

PPCHPAGCH

PNCH

PRACH

PDTCH

PACCHPTCCH

PBCHPacket Broadcast Channels

PCCCHPacket Common Control Channels

PDCCHPacket Dedicated Control Channels

PTCHPacket Traffic Channels


PacketTraffic Channels

PDTCH Packet Data Transfer; (multislot)

PACCH DL & UPPDCH

Signalling: resource allocation,acknowledgements, PC, TA, etc.

PBCCH

Signallingand Control

PCCCH

PPCH

PRACH MS initiates uplink transfer

PAGCH Resource assignment to an MS

PNCH Notifying PtM Packet Transfer **

Broadcast of packet dataspecific information

DL

UL

DL

DL

DL

Paging MSs for packet dataand circuit switched services

PTCCH Packet timing advance channel

Additional logical channels in (E)GPRS 2/2

** Not supported in S10


Packet data logical channel:PBCCH 1/5• PBCCH available in BSS S10.5

• GPRS and EGPRS will not impact on AGCH and PCH

• PBCCH broadcast packet data specific System Information (PSI1-13). If PBCCH is not allocated, the packet data specific system information is broadcast on BCCH (SI13).

• Increased data rates will lead to heavier signalling demand for given traffic occupancy and applications

• PBCCH traffic is not carried on TRXSIG • MS attached to (E)GPRS is not required to monitor BCCH if PBCCH

exists• PBCCH must be on the same TRX as the BCCH (Nokia implementation)• GMSK (MCS1-4) is used on packet control channels. 8-PSK modulation

is used only on the packet traffic data channel PDTCH.• Own neighbour cell lists for GPRS• Own cell re-selection parameters for (E)GPRS (C31 & C32)


Packet data logical channels:PCCCH 3/5

• Network operation mode I (NMO 1, 0): the network sends a CS paging message for a GPRS-attached MS, either on the same channel as the GPRS paging channel (i.e., the packet paging channel or the CCCH paging channel), or on a GPRS traffic channel. This means that the MS needs only to monitor one paging channel, and that it receives CS paging messages on the packet data channel when it has been assigned a packet data channel.

• Network operation mode II (NMO 2, 1): the network sends a CS paging message for a GPRS-attached MS on the CCCH paging channel, and this channel is also used for GPRS paging. This means that the MS needs only to monitor the CCCH paging channel, but that CS paging continues on this paging channel even if the MS has been assigned a packet data channel.

• Network operation mode III (NMO 3, 2): the network sends a CS paging message for a GPRS-attached MS on the CCCH paging channel, and sends a GPRS paging message on either the packet paging channel (if allocated in the cell) or on the CCCH paging channel. This means that an MS that wants to receive pages for both circuit-switched and packet-switched services shall monitor both paging channels if the packet paging channel is allocated in the cell. No paging co-ordination is performed by the network.


Packet data logical channels: PCCCH 2/5

• PPCH is used to page an MS prior to downlink packet transfer. PPCH and CPPCH use paging groups in order to allow usage of DRX mode. PPCH can be used for paging of both circuit switched and packet data services. The paging for circuit switched services on PPCH is applicable for class A and B GPRS MSs in Network operation mode I, see 3GPP TS 23.060

Mode Circuit Paging Channel GPRS Paging Channel Paging co-ordination

Packet Paging Channel Packet Paging ChannelI CCCH Paging Channel CCCH Paging Channel Yes

Packet Data Channel Not ApplicableII CCCH Paging Channel CCCH Paging Channel NoIII CCCH Paging Channel Packet Paging Channel No

CCCH Paging Channel CCCH Paging Channel

Paging co-ordination = CS pages can be sent through SGSN and via PPCH



• The network may provide co-ordination of paging for circuit-switched and packet-switched services.

• Paging co-ordination means that the network sends paging messages for circuit-switched services on the same channel as used for packet-switched services, i.e., on the GPRS paging channel or on the GPRS traffic channel, and the MS needs only to monitor that channel. Three network operation modes are defined.



• PAGCH is used in the packet transfer establishment phase to send resource assignment to an MS prior to packet transfer.

• PNCH is used to send a PTM-M (Point To Multipoint - Multicast) notification to a group of MSs prior to a PTM-M packet transfer.

• PRACH is used by MS to initiate uplink transfer for sending data or signalling information. Packet Access burst and Extended Packet Access burst are used on PRACH. Extended Packet Access burst is used on CPRACH


Packet data logical channels 5/5

• PACCH conveys signalling information related to a given MS. The signalling information includes e.g. acknowledgements and power control information. PACCH carries also resource assignment and reassignment messages, comprising the assignment of a capacity for PDTCH(s) and for further occurrences of PACCH. The PACCH shares resources with PDTCHs, that are currently assigned to one MS. Additionally, an MS that is currently involved in packet transfer, can be paged for circuit switched services on PACCH.

• PTCCH/U is used to transmit random access burst to allow estimation of the timing advance for one MS in packet transfer mode.

• PTCCH/D is used to transmit timing advance information updates to several MS. One PTCCH/D is paired with several PTCCH/U’s.

• PDTCH is a channel allocated for data transfer. It is temporarily dedicated to one MS or to a group of MSs in the PTM‑M case. In the multislot operation, one MS may use multiple PDTCHs in parallel for individual packet transfer.


Mapping of PBCCH/PCCCH DL

B0 B1 B2 T B3 B4 B5 X B6 B7 B8 T B9 B10 B11 X

X = Idle frameT = Frame used for PTCCH

B0 - B11 = Radio blocks

A physical channel allocated to carry packet logical channels is called a packet switched channel (PDCH). A PDCH shall carry packet logical channels only. Packet switched logical channels are mapped dynamically onto a 52-multiframe. The 52-multiframe consists of 12 blocks of 4 consecutive frames, 2 idle frames and 2 frames used for the PTCCH, as shown in figure. PCU handles radio blocks 0 – 11. BTS handles the rest of the radio blocks.


Signalling configuration

For the logical signalling channels , the blocks are assigned in a particular ordered list, with the sequence shown below.

B0, B6, B3, B9, B1, B7, B4, B10, B2, B8, B5, B11

Ordered list for signalling.


Logical channels mapping onto PDCH (DL)

The logical channels are mapped according to the rules described below. i) The PBCCH is mapped onto the 52-multiframe. The operator parameter BS_PBCCH_BLKS specifies

the number of radio blocks allocated for PBCCH. The blocks are allocated according to the ordered list above.

ii) The radio blocks which are not available for paging, defined by the operator parameter

BS_PAG_BLKS_RES, are allocated according to the ordered list after the last PBCCH allocation. These blocks can be used for PAGCH, PDTCH and PACCH. These blocks can carry assignment messages, data and TBF associated control messages.

iii) The remainder of the radio blocks in the 52-multiframe can be used for PPCH, PAGCH, PDTCH and

PACCH. These blocks can carry paging messages, assignment messages, data and TBF-associated control messages.


Example of DL mapping

Below is an example of the DL PBCCH/PCCCH mapping, where BS_PBCCH_BLKS = 3 and

BS_PAG_BLKS_RES = 4.

An example of DL PBCCH/PCCCH mapping onto the 52-multiframe.

The PCU must clearly determine the priority for each type of message on a given block.

PBCCH PBCCHPAGCH,PDTCH

orPACCH

PAGCH,PDTCH

orPACCH

PAGCH,PDTCH

orPACCH

PAGCH,PDTCH

orPACCH

PBCCH

PPCH,PAGCH,PDTCH

orPACCH

PPCH,PAGCH,PDTCH

orPACCH

PPCH,PAGCH,PDTCH

orPACCH

PPCH,PAGCH,PDTCH

orPACCH

PPCH,PAGCH,PDTCH

orPACCH

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10

B11


Mapping onto PDCH in UL

For the uplink direction, the only signalling resource is PRACH. The radio blocks can carry PDCH traffic in addition to this. By use of the parameter BS_PRACH_BLKS, it is possible to define those blocks that can only carry PRACH. BS_PRACH_BLKS = 5 (number of blocks that are fixed allocated for PRACH per multiframe)

PRACH

(fixed)

PRACH

(fixed)

PRACH

(fixed)

PRACH

(fixed)

PRACH

(fixed)

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11

Table 1. An example of fixed PRACH mapping onto 52-multiframe.


PBCCH/PCCCH DL/UL : Conclusion

• RLC control blocks must be transmitted with GPRS CS-1 Coding.

• Support of 8-PSK in UL is optional for the EGPRS MSs


• New channel• PBCCH/PCCCH channel combination (MPBCCH in MML)

• PBCCH+PCCCH+PDTCH+PACCH+PTCCH– PBCCH, Packet Broadcast Control Channel– PCCCH, Packet Common Control Channel– PDTCH, Packet Data Traffic Channel– PACCH, Packet Associate Control Channel– PTCCH, Packet Timing Advance Control Channel

• PBCCH/PCCCH is hopping with the group the TS belongs to (BB)

• Only one MPBCCH timeslot per SEGMENT

• In S9 on PDCH: PDTCH+PACCH+PTCCH (TCHF in MML)

Packet data logical channels


• • PBCCH TRX channel configuration• MPBCCH can be located in BCCH TRX in any of the time slots 1

… 7

• Optionality

• When PRFILE class 2 parameter bsc_gprs_param_enabled is in use, the operator can use PBCCH/PCCCH as a standard feature.

BCCH PBCCHTSL0 TSL1 TSL2 TSL3 TSL4 TSL5 TSL6 TSL7

PBCCH/PCCCH


Radio Resource (RR) operating modes

• Packet idle mode• No Temporary Block Flow exists• MS listens to the PBCCH and to the paging sub-channel for

the paging group the MS belongs to in idle mode. If PCCCH is not present in the cell, the mobile station listens to the BCCH and to the relevant paging sub-channels

• Packet transfer mode• MS is allocated radio resource providing a Temporary Block

Flow on one or more physical channels• When selecting a new cell, mobile station leaves the packet

transfer mode, enters the packet idle mode where it switches to the new cell, read the system information and may then resume to packet transfer mode in the new cell

• Dual transfer mode• MS has an ongoing RR connection and is allocated radio

resource providing a Temporary Block Flow on one or more physical channels

• While in dual transfer mode the MS performs all the tasks of dedicated mode


EGPRS Modulation and Coding Schemes

• EGPRS has nine basic coding schemes, MCS-1...9.

• In general, a higher coding scheme has higher coding rate, and consequently higher peak throughput, but it also tolerates less noise or interference.

• The figure shows throughput vs. C/I of EGPRS coding schemes in TU50iFH, without incremental redundancy.

• The basic unit of transmission is radio block (= 4 bursts = 20 ms on average), which contains one or two RLC blocks.

0

10

20

30

40

50

60

0 5 10 15 20 25 30

MCS-1MCS-2MCS-3MCS-4MCS-5MCS-6MCS-7MCS-8MCS-9

Frequency Hopping Network

Frequency Hopping Network


EGPRS Channel Coding

• EGPRS channel coding consistsof separate data and headercoding, as shown in the figurefor MCS-9 downlink.

• Coding of data part:• Data part includes user

data, two bits from RLCheader, BCS (block check sequence)and tail bits.

• Coded using 1/3 convolutional code.• Punctured with a selectable puncturing

scheme (P1, P2 or P3).• Two separate data parts for MCS-7...9.

• Header part:• Includes RLC/MAC header information and

information on the coding of the data part (like used puncturing scheme).

• Convulutional coding + puncturing.

USF

encoded USF P2 P3

P1 P2 P3

puncturing puncturing

1st burst2nd burst3rd burst4th burst

1/3 tailbitingconvolutional coding

block coding

P1

header FBI+E data 2 BCF tail

1/3 convolutional coding

mother code

protected

header

4 TDMA bursts = 20 ms

FBI+E data 1

mother code

BCFtail

puncturing

1/3 convolutional coding


GPRS & EGPRS Coding Schemes

codingscheme

modulation RLC blks /radio blk

FECcode rate

user bits /20 ms

bit rate(bps)

CS-1 1 0.45 160 8,000CS-2 1 0.65 240 12,000CS-3 1 0.75 288 14,400

GPRS

CS-4 1 n/a 400 20,000MCS-1 1 0.53 176 8,800MCS-2 1 0.66 224 11,200MCS-3 1 0.85 296 14,800MCS-4

GMSK

1 1.00 352 17,600MCS-5 1 0.38 448 22,400MCS-6 1 0.49 592 29,600MCS-7 2 0.76 448+448 44,800MCS-8 2 0.92 544+544 54,400

EGPRS

MCS-9

8-PSK

2 1.00 592+592 59,200


EGPRS MCS´s

37 octets 37 octets 37 octets37 octets

MCS-3

MCS-6

Family A

MCS-9


MCS-2

MCS-5

MCS-7

Family B

22 octets22 octets

MCS-1

MCS-4

Family C

34+3 octets34+3 octets

MCS-3

MCS-6Family A

padding

MCS-8


• The MCSs are divided into different families A,B and C.

• Each family has a different basic unit of payload: 37 (and 34), 28 and 22 octets respectively.

• Different code rates within a family are achieved by transmitting a different number of payload units within one Radio Block.

• For families A and B, 1 or 2 or 4 payload units are transmittes, for family C, only 1 or 2 payload units are transmitted

• When 4 payload units are transmitted (MCS 7, MSC-8 and MCS-9), these are splitted into two separate RLC blocks (with separate sequence BSN numbers and BCS, Block Check Sequences)

• The blocks are interleaved over two bursts only, for MCS-8 and MCS-9.

• For MCS-7 the blocks are interleaved over four bursts


Time frames time slots and bursts

DOCUMENTTYPE 1 (1)

TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere

0 1 2 3 4 5 6 2042 2043 2044 2045 2046 2047

0 1 2 3

0 1

1 (26-frame) multiframe = 26 TDMA frames (120 ms)

(= 51 (26-frame) multiframes or 26 (51-frame) multiframes)

47 48 49 50

24 25

1 (51-frame) multiframe = 51 TDMA frames (3060/13 ms)

0 1 2 3 46 47 48 49 500 1 2 3 4 22 23 24 25

0 1 2 3 4 5 6 7

1 TDMA frame = 8 time slots (120/26 or 4,615 ms)

1 time slot = 156,25 symbol durations (15/26 or 0,577 ms)

(1 symbol duration = 48/13 or 3,69 µs)

TB Encrypted bits Training sequence Encrypted bits TB GP8,2535826583

Fixed bits TB GP8.253

TB Encrypted bits Encrypted bits TB GP8,2539643

TB Encrypted bits TB GP68,25336418

339

142

Normal burst (NB)The number shown are in symbols

Frequency correction burst (FB)

Access burst (AB)

(TB: Tail bits - GP: Guard period)

1 superframe = 1 326 TDMA frames (6,12 s)

Synchronization sequence

Synchronization sequence

Synchronization burst (SB)

1 hyperframe = 2 048 superframes = 2 715 648 TDMA frames (3 h 28 mn 53 s 760 ms)

3TB

NOTE: GMSK modulation: one symbol is one bit 8PSK modulation: one symbol is three bits

Ref: TS 05.01


Data treatment principle in RF layer

User data

"Additional info" that does not require extra protection

Header part, robust coding for secure transmission

Adding redundancy

Puncturing of the coded

info


Interleaving over 2 bursts(header: 4 bursts)

Decreasing redundancy

Adding redundancy

MCS-9 coding and puncturing

P2 P3P1 P2

puncturingpuncturing

1836 bits

USF RLC/MACHdr.

36 bits

Rate 1/3 convolutional coding

135 bits

612 bits

612 bits124 bits36 bitsSB = 8

1392 bits

45 bits

Data = 592 bits BCS TB

612 bits

612 bits 612 bits

1836 bits

Rate 1/3 convolutional coding

EFBIData = 592 bits BCS TBEFBI

612 bits 612 bits 612 bits

P3 P1

3 bits

HCS

puncturing

Ref: TS 03.64

1 1 12 6

Data rate:

skbms

/2,5920

5922

Robust coding for header

Normal burst: 2x58x3 bits




BP: 15/26 ms BP: 15/26 ms BP: 15/26 ms BP: 15/26 ms

skbms

/6,6920

1392 20 ms


EGPRS RLC/MAC header for data block

Bit8 7 6 5 4 3 2 1 Octet

TFI RRBP ES/P USF 1BSN1 PR TFI 2

BSN1 3BSN2 BSN1 4

CPS BSN2 5

Bit8 7 6 5 4 3 2 1 Octet

TFI Countdown Value SI R 1BSN1 TFI 2

BSN2 BSN1 3BSN2 4

Spare PI RSB CPS 5Spare 6

Downlink:

Uplink:

Ref: TS 04.60

• Three header types for EGPRS RLC/MAC data block

• Example: Header type 1 (header for MCS-7, MCS-8 and MCS-9)


Coding parameters

EGPRS modulation and coding schemes:

Scheme Code rate Header Code rate

Modulation RLC blocks per Radio

Block (20ms)

Raw Data within one

Radio Block

Family BCS Tail payload

HCS Data rate kb/s

MCS-9 1.0 0.36 2 2x592 A 59.2

MCS-8 0.92 0.36 2 2x544 A 54.4

MCS-7 0.76 0.36 2 2x448 B

2x12 2x6

44.8

MCS-6 0.49 1/3 1 592 544+48

A 29.6 27.2

MCS-5 0.37 1/3

8PSK

1 448 B 22.4

MCS-4 1.0 0.53 1 352 C 17.6

MCS-3 0.80 0.53 1 296 272+24

A 14.8 13.6

MCS-2 0.66 0.53 1 224 B 11.2

MCS-1 0.53 0.53

GMSK

1 176 C

12

6

8

8.8

NOTE: the italic captions indicate the padding.

Ref: TS 03.64


MS classes for multislot capability 1/4• When an MS supports the use of multiple timeslots it shall belong

to a multislot class as defined below

• 29 multislot classes specifiedMultislot

class Maximum number of slots Minimum number of slots Type

Rx Tx Sum Tta Ttb Tra Trb 1 1 1 2 3 2 4 2 1 2 2 1 3 3 2 3 1 1 3 2 2 3 3 2 3 1 1 4 3 1 4 3 1 3 1 1 5 2 2 4 3 1 3 1 1 6 3 2 4 3 1 3 1 1 7 3 3 4 3 1 3 1 1 8 4 1 5 3 1 2 1 1 9 3 2 5 3 1 2 1 1

10 4 2 5 3 1 2 1 1 11 4 3 5 3 1 2 1 1 12 4 4 5 2 1 2 1 1 13 3 3 NA NA a) 3 a) 2 14 4 4 NA NA a) 3 a) 2 15 5 5 NA NA a) 3 a) 2 16 6 6 NA NA a) 2 a) 2 17 7 7 NA NA a) 1 0 2 18 8 8 NA NA 0 0 0 2 19 6 2 NA 3 b) 2 c) 1 20 6 3 NA 3 b) 2 c) 1 21 6 4 NA 3 b) 2 c) 1 22 6 4 NA 2 b) 2 c) 1 23 6 6 NA 2 b) 2 c) 1 24 8 2 NA 3 b) 2 c) 1 25 8 3 NA 3 b) 2 c) 1 26 8 4 NA 3 b) 2 c) 1 27 8 4 NA 2 b) 2 c) 1 28 8 6 NA 2 b) 2 c) 1 29 8 8 NA 2 b) 2 c) 1

• a) = 1 with frequency hopping, = 0 without frequency hopping.

• b) = 1 with frequency hopping or change from Rx to Tx, = 0 without frequency hopping and no change from Rx to Tx.

• c) = 1 with frequency hopping or change from Tx to Rx, = 0 without frequency hopping and no change from Tx to Rx.

• Type 1 MS are not required to transmit and receive at the same time.

• Type 2 MS are required to be able to transmit and receive at the same time.

• For HSCSD, only multislot classes 1 - 18 are recognised. An MS with a higher multislot class number shall indicate a suitable multislot class less than 19 for HSCSD applications (see 3GPP TS 04.08).


MS classes for multislot capability 2/4• Rx: Rx describes the maximum number of receive timeslots that the

MS can use per TDMA frame. The MS must be able to support all integer values of receive TS from 0 to Rx (depending on the services supported by the MS). The receive TS need not be contiguous. For type 1 MS, the receive TS shall be allocated within window of size Rx, and no transmit TS shall occur between receive TS within a TDMA frame.

• Tx:Tx describes the maximum number of transmit timeslots that the MS can use per TDMA frame. The MS must be able to support all integer values of transmit TS from 0 to Tx (depending on the services supported by the MS). The transmit TS need not be contiguous. For type 1 MS, the transmit TS shall be allocated within window of size Tx, and no receive TS shall occur between transmit TS within a TDMA frame.

• Sum: Sum is the total number of uplink and downlink TS that can actually be used by the MS per TDMA frame. The MS must be able to support all combinations of integer values of Rx and Tx TS where 1 <= Rx + Tx <= Sum (depending on the services supported by the MS). Sum is not applicable to all classes.


MS classes for multislot capability 3/4• Tta: Tta relates to the time needed for the MS to perform adjacent cell signal

level measurement and get ready to transmit. • For type 1 MS it is the minimum number of timeslots that will be allowed between the end of

the previous transmit or receive TS and the next transmit TS when measurement is to be performed between. It should be noted that, in practice, the minimum time allowed may be reduced by amount of timing advance.

• For type 1 MS that supports extended TA, the parameter Tta is increased by 1 if TA > 63 and there is a change from RX to TX.

• For type 2 MS it is not applicable.

• For circuit switched multislot configurations, Tta is not applicable.

• Ttb: Ttb relates to the time needed for the MS to get ready to transmit. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected.

• For type 1 MS it is the minimum number of timeslots that will be allowed between the end of the last previous receive TS and the first next transmit TS or between the previous transmit TS and the next transmit TS when the frequency is changed in between. It should be noted that, in practice, the minimum time allowed may be reduced by the amount of the timing advance.

• For type 1 MS that supports extended TA, the parameter Ttb = 2 if TA > 63 and there is a change from RX to TX.

• For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last transmit burst in a TDMA frame and the first transmit burst in the next TDMA frame.


MS classes for multislot capability 4/4• Tra: Tra relates to the time needed for the MS to perform adjacent cell signal level

measurement and get ready to receive.

• For type 1 MS it is the minimum number of timeslots that will be allowed between the previous transmit or receive TS and the next receive TS when measurement is to be performed between.

• For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.

• Trb: Trb relates to the time needed for the MS to get ready to receive. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected.

• For type 1 MS it is the minimum number of timeslots that will be allowed between the previous transmit TS and the next receive TS or between the previous receive TS and the next receive TS when the frequency is changed in between.

• For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.


MS multislot example

• Multislot class 5 MS in circuit switched configuration• Five basic configurations of channels are possible

R x

T x

R x = 2

T t=1 T x = 2

R x

T x

R x = 2

T t=1

T x<2

R x

T x

R x<2 T t > 1 T x = 2

T h e s e f i v e c o m b i n a t i o n s c a n b e r e p e a t e d a t t h e s i x o t h e r p o s i t i o n s t h a t c a n b e f i t t e d

w i t h i n t h e s a m e T D M A f r a m e

R x

T x

R x = 2 T t > 1

T x<2

T r a > 3

T r a = 3 T r a = 3

T r a = 3

R x

T x

R x<2 T x = 2 T r a > 3

T t=1

A l l p o s s i b l e t i m e s l o t s u s e d D o w n l i n k b i a s e d a s s y m e t r y

A l t e r n a t i v e d o w n l i n k b i a s e d a s s y m e t r y U p l i n k b i a s e d a s s y m e t r y( n o t p r o h i b i t e d b y m u l t i s l o t c l a s s )

A l t e r n a t i v e u p l i n k b i a s e d a s s y m e t r y( n o t p r o h i b i t e d b y m u l t i s l o t c l a s s )Ref: TS 05.02


EGPRS Radio Planning


Signalling: mapping of PBCCH/PCCCH DL

0 4 8

Block 0 …

1712 21 25 34 38 47 5143

Block 11

30

0

7

.

.

Idle, used by BTS data

52-Multiframe:

PBCCH (for example in RTSL 3, amount of PBCCH blocks in MF is 2) BCCH in RTSL 0

Block 6


PBCCH data & broadcasting rules

• The PBCCH data consists of three groups:

PSI1

PSI High repetition (HR) – up to 16 messages

PSI Low repetition (LR) – up to 63 messages

• These groups are broadcast on the PBCCH with the following rules:

i) PSI1 -> B0 when TC=0

ii) If BS_PBCCH_BLKS > 1 then PSI1 -> B6 too, when TC=0

iii) The PSI messages in the group sent with high repetition rate shall be sent in a sequence determined by the network and starting at TC = 0, using the PBCCH blocks within each multiframe which are not occupied according to rule i) or ii). The sequence of these PSI messages shall be repeated starting at each occurrence of TC = 0.

iv) The PSI messages in the group sent with low repetition rate shall be sent in a sequence determined by the network and continuously repeated, using the PBCCH blocks within each multiframe which are not occupied according to rules i) to iii)


Example PBCCH usage 1/2

PSI1_REPEAT_PERIOD TC value B0 B6 B3

0 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(1) LR(2) LR(3)

1 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(4) LR(5) LR(1)

2 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(2) LR(3) LR(4)

3 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(5) LR(1) LR(2)

4 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(3) LR(4) LR(5)

1 PSI1_REPEAT_PERIOD

0 0 PSI1 PSI1 HR(1)

1 HR(2) HR(3) HR(4)

2 LR(1) LR(2) LR(3)

1 SEQUENCE RESTART PERIOD =(1 - PSI_COUNT_LR) timesPSI1_REPEAT_PERIOD in this case, about 3.6 seconds

Contents always known (PSI1)

Contents always known after receiving slot once

Contents may change fromone PSI1_REPEAT_PERIODto the other (sliding)

This is the minimum time to receive all PSI messages oncein this case, about 1.44 seconds

Parameters setting by planner:BS_PBCCH_BLKS = 3PCU will calculate the following:PSI1_REPEAT_PERIOD = 3PSI_COUNT_HR = 4PSI_COUNT_LR = 5


Example PBCCH usage 2/2

ETSI 04.60, 5.5.1.2

• While camping on a cell where PBCCH is present, the mobile station shall attempt to receive the PSI1 message at least every 30 seconds. The mobile station shall then take into account any occurrence of the PSI1 message that may be received on PACCH during packet transfer mode or on PCCCH during periods in packet idle mode. If the PSI1 message is not received, the mobile station shall attempt to receive this message on PBCCH during periods in packet idle mode.

• If the mobile station has not received the PSI1 message within the last 30 seconds, it shall attempt to receive the PSI1 message each time it is scheduled on PBCCH. Such attempts shall be made during both packet idle and packet transfer modes. A mobile station in packet transfer mode may suspend its TBF for this purpose (see 5.5.1.4.2).

• PSI1 reception failure• If the mobile station has not received the PSI1 message within the

last 60 seconds, a PSI1 reception failure has occurred. A PSI1 reception failure shall result in a cell reselection.


Autonomous cell re-selection criteria

• C1 minimum signal level criterion

• C31 signal level threshold criterion for applying hierarchical cell

structures (HCS)

• C32 cell ranking criterion to select cells among those with the same

priority

C31/C32 criteria need PBCCH allocated in serving cell

The following cell re-selection criteria are used for GPRS:

If PBCCH is not allocated, MS shall perform cell re-selection according to C2 criteria

The cell re-selection criteria C31 and C32 are provided as a complement to the current GSM cell re-selection criteria (C2). C31/C32 provide a more general tool to make cell planning for GPRS, as similar to existing planning in GSM, possible.


C1

C1 is used as a minimum signal level criterion for cell re-selection for GPRS in the same way as for GSM Idle mode, but with specific GPRS parameters. (3GPP 05.08)

C1 = (A ‑ Max(B,0))A = RLA_P - GPRS_RXLEV_ACCESS_MIN

B = GPRS_MS_TXPWR_MAX_CCH - P

RLA_P = received level average for each of the carriers in BA(GPRS)

GPRS_RXLEV_ACCESS_MIN = minimum received signal level at the MS required for access to the system

GPRS_MS_TXPWR_MAX_CCH = the maximum TX power level an MS may use when accessing the system

P = maximum RF output power of the MS

GPRS_RXLEV_ACCESS_MIN & GPRS_MS_TXPWR_MAX_CCH parameters for both serving and neighbouring cells are broadcast on PBCCH


C31C31 is used as a signal level threshold criterion parameter to determine whether prioritised hierarchical GPRS and LSA cell re-selection shall apply . (3GPP 05.08)

C31(s) = RLA_P(s) - HCS_THR(s) (serving cell) C31(n) = RLA_P(n) - HCS_THR(n) - TO(n) * L(n) (neighbour cell)RLA_P = Average Receive Signal Strength measured by the Mobile for each of the carriers in BA(GPRS).HCS_THR (Hierarchical Cell Structure Threshold) = 0-31 (-110, -108… -48 dBm). This is the signal threshold for applying HCS GPRS and LSA cell re-selection.

TO(n) = GPRS_TEMPORARY_OFFSET(n) * H(GPRS_PENALTY_TIME(n) - T(n))

H(x) = 0 for x < 0

1 for x 0

L(n) = 0 if PRIORITY_CLASS(n) (PRC Parameter in NOKIA, 0-7)= PRIORITY_CLASS (s)

1 if PRIORITY_CLASS(n) PRIORITY_CLASS (s)

HCS_THR, PRIORITY_CLASS, GPRS_TEMPORARY_OFFSET and GPRS_PENALTY_TIME parameters are broadcast on PBCCH


C31

From ETSI 05.08 (Section 10.1.3)

• At least for every new sample or every second, whichever is the greatest, the MS shall update RLA_P and calculate the value of C1, C31 and C32 for the serving cell and the non-serving cells. The MS shall make a cell re-selection if:

• i) The path loss criterion parameter (C1) for the serving cell falls below zero.

• ii) A non-serving suitable cell (see 3GPP TS 03.22) is evaluated to be better than the serving cell. The best cell is the cell with the highest value of C32 among

• those cells that have the highest PRIORITY_CLASS among those cells that have highest LSA priority among those that fulfill the criterion C31 >= 0, or

• all cells, if no cells fulfill the criterion C31 >= 0.


Cell re-selection algorithm

The MS shall perform a cell re-selection if:

• C1 for the serving cell falls below zero

• A neighbouring cell is found to be better than the serving cell. The best cell is the one with the highest C32 value among

— those cells that have the highest PRIORITY_CLASS among those that have highest LSA priority among those that fulfil the criterion C31 0

— all cells, if no cell fulfil the criterion C31 0

At least for every new sample or every second, whichever is the greatest, the MS shall update RLA_P and calculate the value of C1, C31 and C32 for the serving cell and the non‑serving cells. (3GPP 05.08)


C31

• If HCS_THR = GPRS_RXLEV_ACCESS_MIN then C31 (s) = C1

• If HCS_THR = -48 then C31(s) will almost always be Negative (have the smallest value).

• Therefore, HCS_THR = -48 dBm would make cell least attractive while HCS_THR = -110 dBm would make the cell most attractive.


C32C32 is used as a cell ranking criterion parameter to select cells among those with the same priority. (3GPP 05.08)

C32(s) = C1(s) (serving cell) C32(n) = C1(n) - GPRS_RESELECT_OFFSET(n) - TO(n) * (1-L(n))

(neighbour cell)

TO(n) = GPRS_TEMPORARY_OFFSET(n) * H(GPRS_PENALTY_TIME(n) - T(n))

H(x) = 0 for x < 0

1 for x 0

L(n) = 0 if PRIORITY_CLASS(n) = PRIORITY_CLASS (s)

1 if PRIORITY_CLASS(n) PRIORITY_CLASS (s)

GPRS_RESELECT_OFFSET = applies an offset and hysteresis value to each cell

GPRS_RESELECT_OFFSET parameter is broadcast on PBCCH


EGPRS service activation

• There can be both EDGE capable and non-capable TRX in EDGE capable BTS (physically could be in the same cabinet)

• BSC must be able to handle GPRS traffic on both TRX types simultaneously

• TRXs with EDGE capable and TRXs without EDGE capability must be split to different BTS objects in BSC

• BSC sees those resources under same BTS as if they were two different BTSs with different BTS identifications. For SGSN that is still one cell ->this needs Multi BCF and Common BCCH functionality

• BSC must take care, that EGPRS is allowed only in EDGE supporting BTS objects

• EDGE capable TRXs can handle also CS services (speech and data).


Multi BCF & common BCCH (S10.5)

• Multi BCF introduces a new radio network object SegmentSegment

• Several BTSs can belong to one Segment

• Only one BTS of the Segment can have BCCH (usually GSM900)

• The Segment can have BTSs which differ in:

• - frequency band (GSM900, EGSM900 and GSM1800, GSM 850, GSM1900)

• - power levels (Talk and UltraSite BTSs)

• - regular and super-reuse frequencies

• - normal and extended cell radius frequencies

• - EDGE capability


EGPRS/GSM Interworking (BSS 10083)Talk Family BTSUltra Site BTS







Segment 1

Segment 2

Segment 3

EDGE-capable and non-EDGE-capableTRXs can be combined into one ‘segment’.

Common BCCH/multi BCF functionalityused to distribute traffic between ‘layers’.

Can be used with, e.g., Talk/Ultrasite


RRM : (E)GPRS Territory Method (S9)

• RRM features optimally manage between circuit-switched and packet-switched services

Packet-switched TerritoryTRX 2

TRX 1

BCCH TCH TCH TCH TCH TCH TCH

TCHTCH P-TCH / TCH

P-TCH / TCH

P-TCH P-TCH

Circuit-switched TerritorySignalling

Circuit-switched Default (E)GPRSCapacity

dedicated (E)GPRS (never filled with speech services)

P-TCH / TCH

P-TCH / TCH

PBCCH

Additional (E)GPRScapacity

can be used for speech

Territory Border moves DYNAMICALLY based on CSW traffic load


Implem

etation tips

Territory method: S9 parameters and ”Segment” concept in S10

BSC levelBSC level territory parameters

- Territory Upgrade Timer (GTUGT)

SegmentSegment levellevel territory parameters

- GPRS preferred BCCH frequency (BFG)

- GPRS enabled (GENA)

BTS levelBTS level territory parameters

- Dedicated GPRS capacity (CDED)

- Default GPRS capacity (CDEF)

TRX levelTRX level territory parameters

- GPRS enabled TRX (GTRX)

GENA is used to determine GPRS

capability of Segment. GENA must be switched off to allow parameter changes in any BTS of

the segment.

BFG is Segment level parameter since there can be only one BCCH-

TRX in a segment

Dedicated and Default GPRS capacity can be set separately to each

BTS

If GENA=N, even if one of the BTS is EDGE capable and has got GTRX=Y, it won’t be able to carry EGPRS traffic


EGPRS (BSS 10083) EDGE and non-EDGE territories

DOCUMENTTYPE


B

Segment-1

BTS-1Non-EDGETRXs

BTS-1’EDGE TRXs

GPRS territory

(E)GPRS territory

GPRS Enabled TRX = offB

GPRS Enabled TRX = off

BTS-2Non-EDGETRXs

BTS-2’EDGE TRXs(E)GPRS territory

Segment-2

•Where separate EDGE and non-EDGE‘layers’ exist, territories can be defined for each-> a segment can have several territories defined.

•BTS Synchronisation permits ‘intelligent’ resource management.

•Territory upgrades must include both BTS id and Seg id. To SGSN segment is one cell which has one Cell Identity (CI). PCU must indicate the BTS identity when requesting GPRS territory upgrade or downgrade.


(E)GPRS BTS segment offsets

TRX-1B

TRX-2

Segment-1

TRX-3

TRX-4

BTS-1GSM900

BTS-2GSM900Ultra/EDGE

TRX-5

TRX-6BTS-3GSM1800

EGPRS territory

GPRS territory

GPRS territory

• BTS-1 is BCCH BTS-> no NBL offset (= 0dB)-> no GPRS access min (def =-105 dBm)

• BTS-2 is Ultra BTS-> NBL offset = +2dB-> GPRS access min = -100 dBm

• BTS-3 is GSM1800 BTS-> NBL offset = -3dB-> GPRS access min = -100 dBm

NonBCCHlayer_offsetNonBCCHlayer_offset is used to estimate the signal level in each BTS object when the measurement is done in BCCH BTS object. PC_MEAS_CHAN parameter (1 bit field field in PSI13) must be set to make MS to do RX_LEV measurements on BCCH (=0) (otherwise done on PDCH).


Separation of GPRS and EGPRS Traffic using DIRE and NBL priorities

TRX-1B

TRX-2

Segment-1

TRX-3

TRX-4

BTS-1

BTS-2EGPRS territory

GPRS territory

BTS-1 is BCCH BTS-DIRE = 0 dB-NBL offset = 0 dB-GPRS Access Min (= -105 dBm def) *-EGENA = N

BTS-2 (non BCCH)-NBL offset = +2 dB-GPRS Access Min =-100 dBm-EGENA = Y

* Recommended: since BTS-1 is (P)BCCH BTS the measured one GPRS_RXLEV_ACCESS_MIN should be equal RXLEV_ACCESS_MIN


(E)GPRS BTS selection

Input parameter to CHM Updated in CHM

Description

MaxTBFinTSL Averaged TBF/TSL

The maximum number of TBF in TSL. Separate uplink downlink values

GPRSNonBCCHlayerRxlevUpperLimit

Upper Rx-lev limit

The minimum RX-level for allocating resources from BTS

GPRSNonBCCHlayerRxlevLowerLimit

Lower Rx-lev limit

Threshold when reallocation to better BTS must be done

DirectGprsAccessBts Direct access threshold

A relative value , used with non BCCH layer offset to compare BTSs and make allocation and reallocation to BTS when Rx-lev is not known

BCCH frequency band

BCCH Band Band of the BTS given in territory update message

Egprs enabled Egprs capability

A flag to indicate BTS is Egprs capable.

Inital TBF is selected in CHM when new TBF is created. Segmentation add complexity to initail BTS selection.


Initial BTS selection DL in the SEG: SELECTION ALGORITHM 1/3

1. Default GPRS / EGPRS type selection. - No exceptions

2. Frequency band, MS Radio access capability - MS RAC capable frequency bands are selected in the segment

- Exception 1

3. Default BTS capability check in the segment - Exception 2

4. Signal check using C_VALUES. BTSs filling the next condition are valid for selection :

Rx-lev (BCCH) - NonBCCHlayer_offset > GPRSnonBCCHlayerRxlevUpperLimit - Exception 3 - Exception 4

Precondition : TBF not yet established *


Initial BTS selection cont. 2/3

5. Direct Access parameter value for BTSs inside segment. Parameter is used to compare BTS objects relative preference: when the BTS parameter non_bcch_layer_offset is less than the segment parameter non_bcch_layer, then the BTS is valid for allocation. If there is no value for non_bcch_layer_offset received for certain BTS, it is not valid. - Exception 5

6. TBF/TSL use in BTS, BTS in segment with minimum downlink TBF/TSL QoS load shall be selected.

When sequence doesn’t make BTS selection BTS is not selected and TBF not created.


Initial BTS selection cont. 3/3

• Exceptions : .

1. MS Radio access capability is not known

- BCCH frequency band shall be selected initially.

2. EGPRS TBF is allocated to non-EGPRS BTS when

-The segment doesn’t have EGPRS capable BTS OR

- Average TBF/TSL MaxTBFinTSL in every EGPRS capable BTS AND average TBF/TSL <MaxTBFinTSL in every GPRS capable BTS.

GPRS TBF is allocated to Egprs BTS when

- The segment doesn’t have GPRS capable BTS OR

- Average TBF/TSL MaxTBFinTSL in every GPRS capable BTS AND average TBF/TSL <MaxTBFinTSL in every EGPRS capable BTS.

3. Rx-level is not known

-This step is ignored and it is only used direct access.

4. Any of the BTSs in the segment does not fill the condition.

- There are no valid resources and no TBF is established.

5. Any DirectAccess BTS is not acceptable in segment

- The closest acceptable is selected


NBL: self regulation

Non-BCCH Layer Offset Measurement and Common BCCH Control

The self regulation of the non-BCCHLayerOffset parameter that is used in defining the usability of the GSM1800 band resources is implemented in Nokia NMS (Nokia NetAct) based on the new non-BCCH layer offset measurement.

The measurement includes counters for absolute offset values from 0 to +40 dB in 1 dB steps. All the samples that are below zero are collected into a separate counter. Also the samples that indicate a difference greater than 40 dB are collected in a counter of their own.

The samples for the measurement are collected at the SACCH signalling rate from each mobile with an ongoing call in a GSM1800 BTS in a segment where the BCCH is on the GSM900 band. When defining the signal level differences between the bands the BSC takes into account the used power levels in order to establish an accurate value of the GSM900-GSM1800 difference.

The statistics are collected BTS specifically in every BTS that is on the GSM1800 band of a segment utilising the Common BCCH Control feature. The BSC forwards the collected statistics to the NMS (Nokia NetAct). This gathers samples of BTSs in a segment into two groups based on if the BTS in question represent the same or another base station site type than the BCCH BTS. For both groups an optimal offset parameter value is calculated. In return the NMS (Nokia NetAct) updates for all BTSs of these groups the respective tuned value of the non BCCH layer offset parameter.

The non BCCH layer offset measurement includes 43 offset sample counters. The complete description of the counters can be found in the document BSC Counters: Non-BCCH Layer Offset Measurement

http://localhost:42019/NED?action=retrieve&identifier=dn00268398&format=text%2Fhtml&pointer=%23ERF1EB92SXX.NSS1-P197-2466


GPRSenabledTRX = offB

GPRSenabledTRX = off

Segment-1

TRX-3

TRX-4

TalkBTS-1GSM900

TalkBTS-2GSM1800



Ultra BTS-3GSM900

GPRS territory

• BTS-1 is BCCH BTS (measured BTS)-> NBL offset = 0 dB-> GPRS access min = -105 dBm-> Not Preferred GPRS BTS• BTS-2 is Talk 1800 BTS-> NBL offset = -3dB->GPRS access min = -100 dBm-> Preferred GPRS BTS• BTS-3 is Ultra 900 BTS-> NBL offset = +2dB-> GPRS access min = -100 dBm-> Not Preferred GPRS BTS

TRX-7

TRX-6

UltraBTS-4GSM1800EGPRS territory

• BTS-4 is Ultra 1800 BTS-> NBL offset = -1dB-> GPRS access min = -100 dBm-> Preferred GPRS BTS

PB

(E)GPRS (BSS 10083) Direct access to non BCCH GPRS BTS

Example of setting Preferred GPRS BTS : GSM1800 (DIRE = 0 dBm for all BTSs def.)


EGPRS TBF (re)allocation based on DIRE offset (Example, DIRE > NBL Offset)

BTS 1BCCH

BTS 2

Segment 1

DIRE = +2 dB (for the whole seg)

NBL=- 1 dB

(E)GPRS TBF Preference

BTS 3 NBL = + 3 dB


EGPRS reallocation of a TBF

TBF reallocation processing can take place if better quality data transfer is expected or BTS packet traffic load is unevenly spread in a segment or between supported frequency bands in a segment.

Procedures used to check TBF reallocation activation need in CHM are in order below. Reallocation request to MAC shall be activated in any of the procedures at once (1-4 ).

1. TBF Rx-lev Reallocation

2. BTS Load Reallocation

3. GPRS TBF in EGPRS territory Reallocation

4. BTS Timeslot Balance Reallocation


EGPRS Reallocation Activation

Reallocation check shall be based on counting block periods given to TBF : TBF specificthreshold counters (parameters) are updated in CHM when TBF is selected for transfer.

1. TBFLoadGuardThreshold, shall be used to prevent too frequent BTS load reallocation checks:• Initially TBFLoadGuardThreshold blocks has been transferred before

the TBF will be checked for a load reallocation need for the first time. Then after each TBFLoadGuardThreshold blocks the check is done.

2. TBFSignalGuardThreshold, shall be used to prevent too frequent Rx-lev signal level reallocation checks:• Initially TBFSignalGuardThreshold RLC radio blocks have been

transferred before the TBF is checked for a signal reallocation need for the first time. Then after each TBFSignalGuardThreshold blocks the check is done

• If signal level is sufficient check is done if better level BTS can be found anyway in a segment.

3. Concurrent TBF checkCHM TBF reallocation need check shall be activated when:• A concurrent TBF is closed, check is done using procedures (1..4) in

Reallocation of a TBF • When reallocation check done CHM shall set TBF load guard counter or

TBF signal guard counter value to preset values.


EGPRS TBF (re)allocation activation based on RX_LEV measurement (UL and DL)

PCU must collect and average RX_LEV measurements from each TBF in multi-BTS segment.

In downlink TBF (-> Packet Transfer Mode) the RX_LEV measurement is received in DOWNLINK ACK/NACK message (C-VALUE ) Receiving frequency of these measurements is dependent on the polling algorithm. MS has averaged the RX_LEV measurements during the polling period.

In uplink TBF BTS includes RX_LEV measurement to each PCU frame. Receiving frequency of these measurements is dependent on the scheduling algorithm. BTS has averaged the RX_LEV measurement over one RLC block.

• TBF (re)allocation to certain BTS is allowed when

RX_LEV (BCCH) - NonBCCHlayer_offset > GRPSNonBCCHlayerRxlevUpperLimit• In case of initial allocation with no measurement results, TBF is allocated to a

DirectGPRSaccess_BTS.• A TBF must be reallocated to another BTS when *

RXLEV (BCCH) - NonBCCHlayer_offset < GPRSnonBCCHlayerRxlevLowerLimit.

This is checked every time a new averaged measurement result is obtained.

*ALWAYS WITHIN THE SEGMENT.


(Re)allocation activation based on BTS load 1/2

• Initial allocation

(E)GPRS TBF can be allocated to any preferred BTS in a segment. Preferred GPRS BTS has DirectGPRSaccessBTS parameter set so that is bigger than nonBCCHlayerOffset. Least loaded BTS is selected based on existing average TBF/TSL count in each BTS. TBF allocation to BTS which average TBF/TSL is more than parameter MaxTBFinTSL defines is not allowed.

• Reallocation

TBF/TSL is followed

- for each BTS (average) and

- for each individual TBF.

Reallocation (to different BTS or within the same BTS) is done when

TBF/TSL for a TBF is > average TBF/TSL of BTS + TBF/TSL reallocation threshold.*

Target BTS can be the currently used BTS, which means intra BTS reallocation. TBF/TSL reallocation threshold is PCU internal PRFILE-parameter.

In case of concurrent TBFs (an MS has both an uplink and downlink TBF), reallocation is done when the above reallocation criteria is true for either of the TBFs.

Reallocation need is checked every time a concurrent TBF is established or deleted, e.g., when an uplink TBF is established along a downlink TBF and when the uplink TBF has ended.


(Re)allocation activation based on BTS load 2/2

• GPRS territory downgrade

Normally average TBF/TSL in a BTS may not be more than defined by parameter MaxTBFinTSL defines (before they were PRFILE parameters, now they are BSC level parameters).

In case of GPRS territory downgrade, it is however allowed. In this case 9 TBF/TSL and 7 TBF/TSL is allowed for downlink and uplink respectively. Target for reallocation due to GPRS downgrade may also be another BTS in a same segment. Target is selected based on TBF/TSL introduced above.

• BTS load based reallocation frequency

There must be timer or counter for each TBF to prevent too frequent reallocations.


EGPRS TBF (re)allocation activation based on

GPRS territory (and viceversa)• Initial EGPRS TBF allocation

TBFs for EGPRS capable MSs are allocated always to EDGE capable BTS. EGPRS TBF can be allocated to non-EDGE capable BTS if

• - there is no EDGE capable BTS in a segment, or

• - the average TBF / TSL is more than or equal to MaxTBFinTSL parameter defines in every EDGE capable BTS.

• EGPRS TBF reallocation

EGPRS TBFs allocated to a non EDGE capable BTS are followed and reallocated to an EDGE capable BTS when its average TBF / TSL is less than MaxTBFinTSL parameter. Reallocation is triggered when the load of an EDGE capable BTS decreases.

• GPRS allocation

GPRS TBF allocation works as EGPRS allocation preferring non-EDGE capable resources.


(E)GPRS Reallocation activation based on TSL balance

BTS TSL allocation is used to balance BTS TSL use spread. Reallocation shall be activated

when TSL s have unequal amount of TBF load.

CHM shall use TBF from highest loaded timeslot when suggesting TBF reallocation to

MAC.• Unequal condition is determined using average in timeslot TBF load. • Relative triggering threshold used

BTSTimeslotBalanceThreshold < ( max TBF load in timeslots / average TBF load in timeslot) to activate reallocation


new PRFILE parameters

1. TBFLoadGuardThreshold, shall be used to prevent too frequent BTS load reallocation checks

Initially TBFLoadGuardThreshold blocks has been transferred before the TBF will be checked for a load reallocation need for the first time. Then after each TBFLoadGuardThreshold blocks the check is done.

2. TBFSignalGuardThreshold, shall be used to prevent too frequent Rx-lev signal level reallocation checks.

Initially TBFSignalGuardThreshold RLC radio blocks have been transferred before the TBF is checked for a signal reallocation need for the first time. Then after each TBFSignalGuardThreshold blocks the check is done.

If signal level is sufficient check is done if better level BTS can be found anyway in a segment.


EGPRS Downlink Packet Transfer (RLC ACK’ed mode)

» VARIABLE WINDOW SIZE • For EGPRS the window size (WS) shall be set by the network

according to the number of timeslots allocated in the direction of the TBF (uplink or downlink). The allowed window sizes are shown in the Table. Preferably, the selected window size should be the maximum.

• The window size may be set independently on uplink and downlink. MS shall support the maximum window size corresponding to its multislot capability.The selected WS shall be indicated within PACKET UL/DL ASSIGNMENT and PACKET TIMESLOT RECONFIGURE using the coding defined in the Table.

• Once a window size is selected for a given MS, it may be changed to a larger size but not to a smaller size, in order to prevent dropping data blocks from the window.

• In case the MS multislot class is not indicated during packet data connection establishment (short access, access request for signalling message transfer), a default window size corresponding to the minimum window size for 1 timeslot (as defined in Table) shall be selected.


Table : Allowed window sizes in EGPRS TBF mode for different multislot allocations

Timeslots allocated (Multislot capability) Window size

Coding 1 2 3 4 5 6 7 8

64 00000 96 00001

128 00010 160 00011 192 00100 Max 224 00101 256 00110 Max 288 00111 320 01000 352 01001 384 01010 Max 416 01011 448 01100 480 01101 512 01110 Max 544 01111 576 10000 608 10001 640 10010 Max 672 10011 704 10100 736 10101 768 10110 Max 800 10111 832 11000 864 11001 896 11010 Max 928 11011 960 11100 992 11101 1024 11110 Max

Reserved 11111 x x x x x x x X


EGPRS Window Size processing and Reallocation

TBF is reallocated and more resources is requested in RLC:

• RLC Window size shall increase

TBF is reallocated and less TBF resources is requested in RLC

• RLC Window size shall remain the same if new timeslot allocation allows current RLC window size use in .

• New timeslot and RLC window size TBF resources shall be sent to MS by MAC

• RLC Window size shall be determined by RLC using timeslot allocation

Constant RLC window size 64 shall be used in unacknowledged RLC mode.


Multiplexing GPRS/EGPRS• GPRS and EGPRS mobile stations can be multiplexed dynamically on the

same PDCH

• Timeslot scheduling algorithm determines if there is a standard GPRS MS and EGPRS MS multiplexed on the timeslot, then at least one Radio Block every 360ms on the downlink must use GMSK coding scheme.

• For MS synchronisation resons, if standard GPRS MS are multiplexed on the PDCH, at least one Radio Block every 360 ms on the Downlink must use GMSK (i.e. standard GPRS or MCS-1to MCS-4) (GSM 04.60 v. 8.5.0)

• When USF is sent to GPRS MS the downlink coding scheme used in multiplexed timeslot shall be restrected to MCS1 to MCS4 (USF is in Header but will GPRS mobile decode header only from MCS1-MCS4) ETSI 03.64, Section 6.6.4.1.1.2. Stealing bits.


Priority Based Scheduling (GPRS QoS phase 1)


Priority based scheduling

QoS in BSC S10.5 = Priority based scheduling

• What is affected:• Channel Allocation• Packet Scheduling

• What is not affected:• Bit rates• Number of users


Priority based scheduling

• Higher priority users will have more transmission turns

• Algorithm provides priorities between TBFs on the same time slot

• Scheduling algorithm works with same principle for both uplink and downlink

• Scheduling of control messages not affected by QoS


How the Priority(QoS) information achieved

• In the UL the Radio Priority is used• Four Radio Priority Levels mapped into four scheduling priority

levels

• In the DL the Precedence Class in Qos Profile is used• Three Precedence Class mapped into three scheduling priority

levels


Priority based scheduling• TBFs are in a queue on the RTSL

• The TBF with the smallest Latest Service Time is transmitted

• After the TBF is transmitted the PCU calculates a new Latest Service Time

• Latest Service Time = Current Time + Scheduling Step Size• Current time = RTSL specific virtual time

• Current time is updated

• For a new TBF • Latest Service Time = Current Time


7

Queue

1 2 3 4 5 6 7 8 9 10 11 12

7 8 9 10 11 12 12 13 14 15 16 17

12 12 12 12 12 12 13 18 18 18 18 18

TBF1 with SSS=6

TBF2 with SSS=1

(time)

52 TDMA frames = 240 ms= 12 blocks

i t i t

The scheduling is done based on latest service time, one TBF at a time is served by the RTSL

...Latest service time

Latest Service Time = Current Time + Scheduling Step Size


How the Priority(QoS) information achieved

DL HIGH PRIORITY SSS 1 ... 123DL NORMAL PRIORITY SSS 1 ... 126DL LOW PRIORITY SSS 1 ... 1212UL PRIORITY 1 SSS 1 ... 123UL PRIORITY 2 SSS 1 ... 12 6UL PRIORITY 3 SSS 1 ... 129UL PRIORITY 4 SSS 1 ... 1212

Parameter Range Default Value


BSS10084 QoS QoS change

• From PCUs point of view the TBFs priority may change anytime

• Uplink: • PCU uses the newest priority it has received from the mobile

station

• Downlink:• PCU uses the priority of the LLC-PDU


MS Specific Flow Control

How:

• The BSC(PCU) informs the SGSN transmission rate and buffering capacity for particular MS

• If the limits exceded the PCU warns the SGSN

• SGSN adjust the flow accordingly

•Flow control prevents overflow of buffers in the PCU

Only DL flow is controlled.

•Cell level flow control already in S9•S10.5 has MS level flow control which also takes care of cell flow control


IR & LA

• SPECS

• Nokia solution (aka improvements and changes from the existing GPRS algorithms)


Incremental Redundancy 1/2

• IR is a physical layer performance enhancement for the acknowledged RLC mode of EGPRS.

• The basis for Incremental Redundancy (IR) is in the selective-reject-ARQ protocol of the RLC layer. The ARQ protocol takes care of requesting and retransmitting incorrectly received blocks.

• IR (II Hybrid ARQ) improves the reception of retransmissions by soft combining the information in the original transmission (which failed) with the received additional information, thereby increasing the probability of correct reception.

• The most important standardised feature of Incremental Redundancy is that MS has mandatory IR combining in its receiver. IR has also been taken into account in the design of the coding schemes and block formats.


Incremental Redundancy 2/2

DOCUMENTTYPE


Data Block

P1 P2 P3

P1 P2 P3

P1

P2

P3

Protection Level 1

1st transmission 2nd retransmissionupon receptionfailure

Stored

Stored

No datarecovered

No datarecovered

Combination : Protection Level x 2

Combination : Protection Level x 3

Stored

Transmitter

ReceiverP1

P1 P2

One MCS

1st retransmissionupon receptionfailure

• In IR-mode, channel coding (redundancy) is increased gradually (Type II Hybrid ARQ)

• If the first transmission of radio block fails, it is retransmitted with different puncturing scheme (P1,P2,P3 defined for each MCS) and soft combined with the old data


• TU 3km/h

• No frequency hopping

Incremental redundancy - example

Thro

ughput

kbit

/s

C/I


Link Adaptation: Introduction

• To maintain good throughput the signal strength should have sufficient value and on the other hand the radio channel interference level should be low.

• Therefore one goal for the Link Adaptation algorithm could be adapt to situations where signal strength compared to interference level is low and changing within time.

• In DL case the EGPRS Link Adaptation shall be based on EGPRS Channel Quality Report received in EGPRS PACKET DOWNLINK ACK/NACK message sent from the MS to network using PACCH to indicate the status of the downlink RLC data blocks received.

• In DL the EGPRS Link Adaptation is based on using the BEP measurement data

• In UL case the EGPRS Link Adaptation is based on the respective BEP measurement values which are received within the UL PCU frames


Link adaptation-MCS Selection-

Link adaptation comprises an initial MCS selection and MCS adaptation

• In the uplink, the entire MCS selection is controlled by one parameter, and MS performs MCS selection according to rules in 04.60.

• In the downlink, MCS selection is performed by the network. This makes trying different MCSs easier and allows finer control in choosing the MCS for retransmissions. Also special situations such as lack of IR memory can be handled separately on a block-by-block basis.

• For initial transmissions:• If IR memory is not full, use MCSpref_IR .• If IR memory is full, use MCSpref_noIR .


Link adaptation-adaptation-

• S10.5 Link adaptation algorithm:

• is based on BEP mean and variance, reported by MS • does not need TS specific BEP values• BEP mapping tablesBEP mapping tables are based on extensive link level simulations (they

may later be updated according to e.g. field measurements)• does not take BLER (ACK/NACK information) into account• has 6 operator parameters which provide good and stable control of the

algorithm• is simple to implement and do not require much computing or additional

memory


Quality , BER and BEP 1/2

• The BER values used to define a quality band are the estimated error probabilities before channel decoding, averaged over the full set or sub set of TDMA frames

• The accuracy to which an MS shall be capable of estimating the error probabilities when on a TCH under static channel conditions is given in the following table

Quality Band Range of actual BER Probability that the

correct RXQUAL band is reported by MS shall exceed (for Full Rate Ch)

RXQUAL_0 Less than 0,1 % 90 %

RXQUAL_1 0,26 % to 0,30 % 75 %

RXQUAL_2 0,51 % to 0,64 % 85 %

RXQUAL_3 1,0 % to 1,3 % 90 %

RXQUAL_4 1,9 % to 2,7 % 90 %

RXQUAL_5 3,8 % to 5,4 % 95 %

RXQUAL_6 7,6 % to 11,0 % 95 %

RXQUAL_7 Greater than 15,0 % 95 %


Quality , BER and BEP 2/2

• The accuracy to which an MS shall be capable of estimating the error probabilities when on a TCH under TU50 channel conditions is given in the following table

Range of actual BER Expected RXQUAL_FULL Probability that expected RXQUAL_FULL is reported shall exceed

Less than 0,1 % RXQUAL_0/1 85 % 0,26 % to 0,30 % RXQUAL_1/0/2 85 % 0,51 % to 0,64 % RXQUAL_2/1/3 85 %

1,0 % to 1,3 % RXQUAL_3/2/4 75 % 1,9 % to 2,7 % RXQUAL_4/3/5 75 % 3,8 % to 5,4 % RXQUAL_5/4/6 90 %

7,6 % to 11,0 % RXQUAL_6/5/7 90 % Greater than 15,0 % RXQUAL_7/6 90 %


Mean_BEP and Std_BEP

• For EGPRS, the MS shall calculate the following values for each radio block (4 bursts) addressed to it:

MEAN_BEPblock = mean(BEP) Mean Bit Error Probability (BEP) of a radio block

CV_BEPblock = std(BEP)/mean(BEP) Coefficient of variation of the Bit Error Probability of a radio block

• Here, mean(BEP) and std(BEP) are the mean and the standard deviation respectively of the measured BEP values of the four bursts in the radio block, calculated in a linear scale.


Link Adaptation Algorithm 1

• Initial MCS to be used when entering the packet transfer mode

• In this case, the MCS to be used is decided according to the operator parameters:

"Initial MCS coding scheme for the acknowledged mode"

"Initial MCS coding scheme for unacknowledged mode"


Link Adaptation Algorithm 2

• MCS selection for initial transmissions of each RLC block in ACK mode

• MCS selection is based on the MEAN_BEP and CV_BEP of the selected modulation.

• The appropriate table below is consulted for MCS selection for GMSK and 8-PSK

CV_BEP-classMEAN_BEP-class

0 1 2 3 4 5 6 7

0 – 3 1 1 1 1 1 1 1 14 2 2 1 1 1 1 1 15 2 2 2 1 1 1 1 16 2 2 2 2 2 2 1 1

7 – 9 2 2 2 2 2 2 2 210 – 19 3 3 3 3 3 3 3 320 – 31 4 4 4 4 4 4 4 4

For GMSK

CV_BEP-classMEAN_BEP-class

0 1 2 3 4 5 6 7

0 – 3 5 5 5 54 5 5 5 55 5 5 5 56 5 5 5 57 5 5 5 58 5 5 5 59 6 5

10 – 16 6 6 6 6 6 6 6 617 – 21 7 7 7 7 7 7 7 722 – 25 8 8 8 8 8 8 8 826 – 31 9 9 9 9 9 9 9 9

For 8-PSK


EDGE Link Adaptation and MCSs• MCS scheme is dynamically selected to maximise throughput, depending

on the radio link conditions

• Different LA algorithms can be envisaged based on different link quality indicators (e.g. BLER, C/I, BEP)

• Bit Error Probability (BEP) is a new MS quality measurement introduced in EDGE for more accurate DL quality reporting

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35 40

C/I dB

Kb

its/

s

MCS-9 MCS-8

MCS-7 MCS-6

MCS-5 MCS-4

MCS-3 MCS-2

MCS-1 Ideal LA Throughput experienced by end user per TSL for the different MCS. TU3, ideal FH and LA.


Link Adaptation and IR Interaction

• IR Only (ETSI 04.60, Table 10)

MCSswitched from

MCSswitched to

PS of last transmission before MCS switch

PS of first transmission after MCS switch

MCS-9 MCS-6 PS 1 or PS 3 PS 1

PS 2 PS 2

MCS-6 MCS-9 PS 1 PS 3

PS 2 PS 2

MCS-7 MCS-5 any PS 1

MCS-5 MCS-7 any PS 2

all other combinations any PS 1


Schemeusedfor

initialtransmi

ssion

Scheme to use for retransmissions after switching to a different MCS

MCS-9Commanded

MCS-8Commanded

MCS-7Commanded

MCS-6-9

Commanded

MCS-6Commanded

MCS-5-7

Commanded

MCS-5Commanded

MCS-4Commanded

MCS-3Commanded

MCS-2Commanded

MCS-1Commanded

MCS-9 MCS-9 MCS-6 MCS-6 MCS-6 MCS-6 MCS-3 MCS-3 MCS-3 MCS-3 MCS-3 MCS-3

MCS-8 MCS-8 MCS-8 MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-3(pad)

MCS-3(pad)

MCS-3(pad)

MCS-3(pad)

MCS-3pad)

MCS-3(pad)








Schemeusedfor

Initialtransmi

ssion

Scheme to use for retransmissions after switching to a different MCS

MCS-9Commanded

MCS-8Commanded

MCS-7Commanded

MCS-6-9

Commanded

MCS-6Commanded

MCS-5-7

Commanded

MCS-5Commanded

MCS-4Commanded

MCS-3Commanded

MCS-2Commanded

MCS-1Commanded


MCS-8 MCS-8 MCS-8 MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)

MCS-6(pad)








Re-segment bit to "1" -> re-segmentation active

Re-segment bit to "0" -> re-segmentation non active

ETSI 04.60, Tables 2 and 3

ARQ Type II(Incremental Redundancy)

ARQ Type I(No Incremental Redundancy)


By adopting the protection level (modifying the coding schemes) Upcoming channel quality is predicted accurately from various measurements of the past one needed for: Accurate measurements of the link quality Set of protection of the information (different protection sets are available) Protection schemes are designed for EGPRS from MCS-1 to MCS-9

EGPRS Air Interface : LALink Adaptation for GPRS


Incremental redundancy :IR (Type II Hybrid ARQ)

Retransmission of the data block can be different to the initial transmission Re-transmission includes additional redundancy (PS1-3) IR needs no information about the link quality For each of the MCSs, it is possible to reach the same data rate with the same protection level but with another puncturing scheme.

EGPRS Air Interface


Coverage Planning


Es/No, Eb/No & C/N

GSMModulation

Es/No C/N

GMSK Es/No=Eb/No C/N = Eb/No +1.3dB

8-PSK Es/No = Eb/No +4.77dB

C/N = Es/No + 1.3dB= Eb/No + 6.14dB

Assumes: Rb=271kb/s GMSK, 822kb/s 8-PSK Rs=271ks/s GMSK/8-PSKB=200kHz


Noise

• The dominant form of noise is thermal noise:

Where

N = noise power

k = Boltmann´s constant (1,38*10-23 J/K)

T = temperature (290 K)

B = bandwidth (271 kHz)

With the above mentioned figures, the noise power is

1,1*10-15 W = -119,6 dBm

kTBN


Required signal strength

• The required signal strength (sensitivity) can be calculated if Noise spectral density, Eb/No requirement and receiver noise figures are known:

• For GSM, where Eb/No is 8 dB and if Freceiver = 4 dB:

S = -119,6 dBm + 8 dB + 4 dB = -107,6 dBm

receiverb FN

ENS 0


GMSK & 8-PSK (1)

GMSK

3/8-8PSK(0,0,1)

(1,0,1)

(0,0,0) (0,1,0)

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

Time


Time


22,5° offset


8-PSK Tx Power Reduction

GMSK

8PSK

Time


Time


Peak to Average of 3,2 dB

Pin

Pout

Back Off= 2 dB

Compression point


Link budgets - Talk speech relative to Ultrasite EGPRS (MCS-5, TU3,10%

BLER). Downlink.

Ultrasite EGPRS v Talk speech dB

Es/No -9.0Incremental redundancy +2.0Fast fading margin +2.0Body loss +3.08-PSK tx back-off -2.0Combiner loss (assumes 1 Ultra/ 2 Talk config.) +3.5Total -0.5

MCS-5 @ 10% BLER = 20kb/s per timeslot, so 60kb/s on downlink for 3+1 terminal

+ values indicate Ultrasite system gain, - values indicate Talk system gain


Link budgets - Talk speech v Ultrasite EGPRS (MCS-5, TU3, 10% BLER).

Uplink.

Ultrasite EGPRS v Talk speech dB

Es/No -9.0Rx sensitivity +2.0Incremental redundancy +2.0Fast fading margin +2.0Body loss +3.08-PSK tx back-off -4.0Total -4.0

+ values indicate Ultrasite system gain, - values indicate Talk system gain


Path loss calculations

• Based on:• Ultrasite TRX, tx combiner by-passed

• For MCS-5, 10% BLER

• Allowable path loss approx. 150dB


General EGPRS link budget issues

• Ultrasite coverage for uplink/downlink for MCS-5 very similar to Talk speech

• GMSK data not subject to tx back-off, thus improving link budget

• Signalling uses GMSK - Ultrasite signalling therefore has better coverage than Talk signalling


EDGE Frequency Planning


TU3nFH: tp vs. C/I

C/I

Th

rou

gh

pu

t

C/I

Th

rou

gh

pu

t

With Impairments


EGPRS frequency planning

• EGPRS highest data rates require high C/I, typ > 20dB for MCS-7, 8 & 9

• Loose re-use patterns will provide optimum performance for all load levels

• For systems with stringent spectrum constraints, EGPRS can offer good performance even with tight re-use patterns (1/3 or 3/9). Load dependent!

• EGPRS traffic suited to BCCH use - typically the layer with highest C/I. But limited no. of TSLs available on BCCH; may need to use TCH layer too.


0

10

20

30

40

50

60

0 5 10 15 20 25 30

MCS-5

MCS-5IR

MCS-6

MCS-6IR

MCS-7

MCS-7IR

MCS-8

MCS-8IR

MCS-9

MCS-9IR

Optimisation

• Network Changes• Microcells• Picocells• Dual Band Allocation • Traffic Management

• Optimization•Antenna Tilting•Parameter Optimization•Effective Fault & Performance Management

• User Throughput - User Perceived Data Rate

• BSS Dimensioning - Less TSL occupancy

IMPA

CT

IMPROVEMENT


EGPRS Simulations


EGPRS simulations

• Simulations performed for EGPRS in 7/21 re-use 1800 MHz network

• Dedicated EDGE layer assumed (one TRX/cell)

• EGPRS load varied within EDGE layer

• Different MCS performances studied


Simulated network


Simulations - EGPRS performance (1) • 100% EGPRS load, TU3 channel

• On the left, simulated throughput of MCS-1

• On the right, simulated throughput of MCS-5

22.4 kb/s per TS8.8 kb/s per TS


Simulations - EGPRS performance (2)

• 100% EGPRS load, TU3 channel

• On the left, simulated throughput of MCS-7

• On the right, simulated throughput of MCS-8

44.8 kb/s per TS 54.4 kb/s per TS


Questionnaire

1. What does EDGE mean?

2. What’s the new modulation introduced by EDGE?

3. What’s EGPRS?

4. How many modulations and coding schemes do we have in EGPRS?

5. Why do we need DAP transmission ?

6. Why 8-PSK modulation use affects the cell coverage?

7. What can we use to counteract the above mentioned effcts?

8. What’s the difference between ARQ I and Hybrid ARQ II?

9. What’s the mechanism to adapt thoughputs with quality of the network?

10. Such mechanism is based on what?

11. What is it IR?

12. Can IR function together with LA?

13. Tell the main difference between LA and IR.

14. Do you remember three of the main features introduced by S10.5?

15. Can we multiplex GPRS with EGPRS traffic in the same PDCH?

16. How initial BTS is selected?

17. (Re)Allocation : which things may trigger (re)allocation of a TBF (within same BTS or onto another BTS)?


Questionnaire (cont.) 18. In which message the MS communicates to the NW about the quality of the network?

19. What is the new IE available in such signalling message?

20. In which modulation are signalling messages sent? And why is that?

21. In terms of header types: what is still the sam and what differs between GPRS and EGPRS? Can you tell the reason?

22. Why in EGPRS we have three different data header types?

23. SRC : what are the main features ?

24. In terms of QoS, what’s new in S10.5 ?

Documents

e Gprs Workshop Orlando 1