gprs air interface aspects general packet radio...

2 MAR | Re |08/00 |

1 1 GPRS General Packet Radio ServicesAir interface aspects

1MAT | 09.09.02 |

GPRSGeneral Packet Radio Services

(Placeholder for a cover picture; this picture should alwayscover the whole slide width as shown here)

GPRS Air Interface aspects

GPRS General Packet Radio ServicesAir interface aspects

1MAT | 09.09.02 |

GPRSPhysical resource

GPRSLogical channels

GPRSAllocation ofphysical resource

2

Your Lecturer is:

Reiner StuhlfauthRohde&Schwarz

Training Center, Munich


1MAT | 09.09.02 |




3

Structure of presentation

�GPRS - Physical resource

�GPRS - Logical channels

�GPRS - Allocation of physical resource

Outline of Presentation


1MAT | 09.09.02 |




4

GPRS Radio Interface GPRS-Burst-Types

Abbreviations :T=Tail Bit (3 Bits/ 8 Bits in leading part of Access BurstF=Flag (1 Bit)G=Guard Period (8,25 Bits/ 68,25 Bits in Access Burst)

T3

T3

T3

T3

T3

T3

T3

T3

T8

57 data bits 57 data bits 26 BitsTraining Sequence

F1

F1 G

8,25

G8,25

G8,25

G8,25

G68,25

142 fixed Bits

64 BitsExtended Training Sequence39 data bits 39 data bits

142 fixed Bits

36 data bits T3

41 BitsTraining Sequence

Normal Burst

Frequency Correction Burst

Synchronisation Burst

Dummy Burst

Access Burst

GPRS uses thesame Burst types asknown from GSM


1MAT | 09.09.02 |




5

GPRS Radio Interface: Common Features to GSM

•GPRS needs Circuit Switched Signalling:FCCH, SCH and BCCH

•GPRS uses GSM Normal Burst for data transport:

•GPRS uses same Modulation: GMSK

TInformation F GInformationFTrainings- sequence

3 57 1 26 31 57 8,25T

T = Tailbits F = Flagbits G = Guardtime

GPRS Radio Interface


1MAT | 09.09.02 |




6

0 1 2 3 4 5 6 7

Signalling: BCCH + FCCH + SCH + CCCH

Circuit switched channels Packet switched channelsPDCH

Capacity on demand: Provides circuit switchedchannels and packet switched channels in a dynamicmanner

Example: Cell with 1 Frequency channel: 1 physical channel for signalling, 4 physical channels for circuit switched TCHand 3 physical channels for packet switched PDCH

GPRS Capacity on Demand


1MAT | 09.09.02 |




7

0 1 2 3 4 5 6 7TN

FN = Frame number TN = Timeslot number

= 1 Frame

0 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 7 0 1 2 3 4 5 6 70 1 2 3 4 5 6 7

Mapping of TCH and PDCH on a frequency channel

GSM TCH: Traffic channel in circuit switched mode, 26-Multiframe

12 x TCH 12 x TCH S I

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Frequency channel

GPRS PDCH:1 Radio Block =4 Bursts


GPRS PDCH: Traffic or signalling channel in packet switched mode

FN

S = SACCH

GPRS Physical Resource


1MAT | 09.09.02 |




8

0 1 2 3 4 5 6 7TN

FN = Frame number TN = Timeslot number

= 1 Frame

0 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 7 0 1 2 3 4 5 6 70 1 2 3 4 5 6 7

Reminder: Mapping of GSM-TCH on a frequency channel

GSM TCH: Traffic channel in circuit switched mode, 26-Multiframe

12 x TCH 12 x TCH S I

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Frequency channel



GPRS PDCH: Traffic or signalling channel in packet switched mode

FN

S = SACCH


GSM-TCH:1 Timeslot in Uplink and Downlink direction,

using the 26 Multiframe


1MAT | 09.09.02 |




9

0 1 2 3 4 5 6 7TN

TN = Timeslot number

= 1 Frame

0 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 7 0 1 2 3 4 5 6 70 1 2 3 4 5 6 7

Mapping of GPRS-PDCH on a frequency channel




1 Radio Blockis the smallesttransport unitin GPRS!

2 Radio Blocksmay belong to 2 different users!=> sharing of physical resources

Radio Block transmits signalling or data


1MAT | 09.09.02 |




10

GSMPhysical resource = 1 Timeslot on 1 Frequency Channel

e.g. ARFCN + TN

GPRS, using Temporary Block Flow to identify radio resourcePhysical resource = N Radio Blocks (=4 Normal Bursts) on 1 or more Timeslots. Temporary Block Flow, TBF identifies allocated physical resource

Allocation of physicalresource

Downlink Uplink

Symmetric data transfer

Downlink Uplink Downlink Uplink

Symmetric data transfer Asymmetric data transfer

fixed

dynamic

Extended dynamic

or

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4

downlink

uplink



1MAT | 09.09.02 |




11


TBF:A Temporary Block Flow is a physical connection usedby two entities to transport Packet Data Units on a packet data physical channel.

TFI:A Temporary Flow Identifier is assigned to every TBF. The TBF is identified by the TFI together with the direction.

TBF = TFI + Direction


1MAT | 09.09.02 |




12

GPRS: Additional Logical Channels

PBCCH

Signallingand Control

PacketTraffic Channels

PCCCH

PPCH

PRACH MS initiates uplink transfer

PAGCH Resource assignment to an MS

PNCH Notifying PtM Packet Transfer

Broadcast of packet dataspecific information

PDTCH Packet Data Transfer; (multislot)

PACCH

DL

UL

DL

DL

DL

DL & ULPTCH

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

Paging MSs for packet dataand circuit switched services

PDCH: Packet Data Channel:


1MAT | 09.09.02 |




13


Logical Channel ComparisonCIRCUIT SWITCHED GSM PACKET SWITCHED GPRS

FCCH No Direct EquivalentSCH No Direct EquivalentBCCH PBCCHPCH PPCHRACH PRACHAGCH PAGCHNCH PNCHSDCCH PCCCH/PACCHTCH PDTCHSACCH PACCHSACCH PTCCHFACCH PACCH

CCCH PCCCH

PDCH


1MAT | 09.09.02 |




14

GPRS Radio InterfaceChannel Combinations

CIRCUIT SWITCHED (51 MFM)i) TCH/F + FACCH/F + SACCH/TFii) TCH/H(0,1) + FACCH/H(0,1) + SACCH/TH(0,1)iii) TCH/H(0,0) + FACCH/H(0,1) + SACCH/TH(0,1) + TCH/H(1,1)iv) FCCH + SCH + BCCH + CCCHv) FCCH + SCH + BCCH + CCCH+SDCCH/4(0..3)+SACCH/C4(0..3)vi) BCCH + CCCHvii) SDCCH/8(0 .7) + SACCH/C8(0 . 7)viii) TCH/F + FACCH/F + SACCH/Mix) TCH/F + SACCH/Mx) TCH/FD + SACCH/MD

GPRS (52 MFM)xi) PBCCH+PCCCH+PDTCH+PACCH+PTCCHxii) PCCCH+PDTCH+PACCH+PTCCHxiii)PDTCH+PACCH+PTCCH

where CCCH = PCH + RACH + AGCH + NCH and PCCCH=PPCH+PRACH+PAGCH+PNCH.

3 new channelcombinations in

GPRS


1MAT | 09.09.02 |




15

GPRS: Signalling InformationSignalling Information about GPRS

Circuit switched

BCCH

PDCH additional PDCH

PBCCH PCCCH

Complete GPRS Info

orPointer to PBCCH

Existence mandatory Existence optional Existence optional

GPRS-Info,GPRS Signalling

AdditionalGPRS-Info


1MAT | 09.09.02 |




16

GPRS: Signalling Information

Broadcast Control Channel

Common Control Channels

Packet Broadcast ControlChannel

Packet Common ControlChannels

Com

plex

ity


1MAT | 09.09.02 |




17

1 2 3 40

1 2 3 40

1 2 3 40

47 48 49 5046

22 23 24 2521

48 49 50 5147

1 2 53 4 60 7 1 2 53 4 60 7 1 2 53 4 60 7

Multiframes used in GSM and GPRS51-Multiframe: GSM-Signalling

26-Multiframe: GSM-Traffic

52-Multiframe: GPRS-Signalling and Traffic

GPRS + GSM Multiframes


1MAT | 09.09.02 |




18

B9 B10 B11B6 B7 B8B3 B4 B5B0 B1 B2 T X XT

B0 - B11 = Radio Blocks T = Frame used for PTCCH X = Idle frame

52 TDMA Frames

52 - Multiframe Structure for PDCH

NB NB NB NB1 Radio Block = 4 TS in consecutive TDMA Frames

Uplink-Multiplexing:PDTCH & PACCH

PDTCH, PACCH & PRACH

or

Downlink-Multiplexing:PDTCH & PACCHPDTCH & PACCH & PCCCHincl. PBCCHPDTCH & PACCH & PCCCHwithout PBCCH

GPRS Multiframe


1MAT | 09.09.02 |




19


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

PTCCH

GPRS Timing Advance on PTCCH

Position of PTCCH on 52-Multiframe

52 Frames

PTCCH is anew logical

channel in GPRS

PTCCH is anew logical

channel in GPRS


1MAT | 09.09.02 |




20


timeslot n timeslot n+1

Guard Period8,25 bit periods

Burst in timeslot n

Burst in timeslot n+1

PowerRamping

GSM Timing Advance and Guard Period


1MAT | 09.09.02 |




21


GSM Timing Advance and Guard Period

BTS MS

BTS sends Timing Advance value to each MS individually to eliminatedelay time effects

MS starts transmitting „Timing Advance“-bit periods earlier to be at the BTS sideright in time


1MAT | 09.09.02 |




22


PTCCH / Uplink

PTCCH / Downlink

= 1 Access Burst

= 1 Radio Block = 4 Normal Bursts

Packet Timing Advance Control Channel, PTCCH

MS sends Access Burst on uplinkNetwork sends Control Message on downlink


1MAT | 09.09.02 |




23


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

PTCCH

GPRS Timing Advance on PTCCH

52 Frames

PTCCH / Uplink

PTCCH / Downlink

= 1 Access Burst

= 1 Radio Block = 4 Normal Bursts

MS has 2 possibilities within 52 Multiframe, butnetwork needs 4 Normal Burst to transmit the message!


1MAT | 09.09.02 |




24

GPRS Radio Interface52-multiframe number n:

uplink TAI=0 TAI=1B0 B1 B2 0 B3 B4 B5 1 B6 B7 B8 2 B9 B10 B11 3

downlink TA_message 1 TA message 1

52-multiframe number n + 1:


downlink TA message 1 TA message 1
















Operation of PTCCH on 52 MultiframeC

ombining 8 tim

es the52 M

ultiframe

to get a PTCC

H-M

ultiframe


1MAT | 09.09.02 |




25






















Operation of PTCCH on 52 Multiframe

TAI = TimingAdvance Identifierto define the Frame,where the MS is allowed to transmit one Access Burston the PTCCH/uplink


1MAT | 09.09.02 |




26






















Operation of PTCCH on 52 Multiframe

Network transmits Timing Advance ControlMessage with length of 4 Normal Burs ts

on PTCCH/Downlink


1MAT | 09.09.02 |




27

GPRS Allocation of physical resource

Allocation of physicalresource

fixed

dynamic

Extended dynamic

Allocation of physical resources can be done belonging3 different modes. Fixed and dynamic allocation is mandatory, extended dynamic allocation is optional.


1MAT | 09.09.02 |




28

downlink

USFRadio Block B(n)

USF = R1

USF = R2

USF = R3

USF =R4

uplink

Radio Block B(n+1)

Monitoring USF in Block B(n)Sends in Block B(n+1) or in Blocks B(n+1) - B(n+4)

GPRS Dynamic AssignmentUSF = Uplink State Flag

USF sent in downlink Radio Blockpoints to the user of the next

uplink Radio Block (or the next 4 Radio Blocks, if USF Granularity bit is set)


1MAT | 09.09.02 |




29

downlink

USFRadio Block B(n)

USF = R1

USF = R2

USF = R3

USF =R4

uplink

Radio Block B(n+1)

Monitoring USF in Block B(n)Sends in Block B(n+1) or in Blocks B(n+1) - B(n+4)

GPRS Extended Dynamic AllocationUSF = Uplink State Flag

USF allowing to transmit 1 or 4 Radio Blocks on that PDCH and on all higher

numbered assigned PDCH’s


1MAT | 09.09.02 |




30



52 TDMA Frames

Timeslot Allocation0 1 2 3 4 5 6 700001011Assigned TimeslotsBitmap example

Allocation Bitmap

010111000110111000111000101001100111



TN4

TN6

TN7

PDCH

= not assigned Radio Block = assigned Radio Block

example

GPRS Fixed Assignment


1MAT | 09.09.02 |




31



52 TDMA Frames


Allocation Bitmap

010111000110111000111000101001100111



TN4

TN6

TN7

PDCH


example


1. Element of fixed assignment: Timeslot Allocation

Vector with 8 elements whichassigns the timeslots that may beused by the MS for the data transfer


1MAT | 09.09.02 |




32



52 TDMA Frames


Allocation Bitmap

010111000110111000111000101001100111



TN4

TN6

TN7

PDCH


example


2. Element of fixed assignment: Allocation Bitmap

Matrix with Nx12 elements: 12 lines, corresponding to the12 Radio Blocks within the 52 Multiframe.N columns, depending on theN assigned timeslots withthe Timeslot Allocation Vector


1MAT | 09.09.02 |




33

Mobile Originated Packet TransferMobile Originated Packet Transfer

MS Net-work

Packet Channel Request1

2 Packet Immediate Assignment

Packet Resource Request3

4 Packet Resource Assignment

PAGCH or AGCH

PRACH or RACH

PACCH

PACCH

Phase One Access

Phase Two Access

(optional)

Packet Channel Request1

2 Packet Immediate Assignment

Packet Resource Request3

4 Packet Resource Assignment

PAGCH or AGCH

PRACH or RACH

PACCH

PACCH

Phase OneAccess

Phase Two Access(optional)

GPRS Packet Data Transfer


1MAT | 09.09.02 |




34


Mobile originated data transfer: GPRS channel request

Channel request via RACH

Packet Channel requestvia PRACH

Single block establishment

One phase access request

One phase access request

or

Short access request

Two phase access request


1MAT | 09.09.02 |




35


Network originated data transfer



Packet Common Control Channels

Packet switched paging

Circuit switched paging

Circuit switched paging

Packet switched paging

or


1MAT | 09.09.02 |




36

Thank you for your attention

??

http://www.rohde-schwarz.comor

[email protected]

Further questions:

?

gprs air interface aspects general packet radio...

Documents