Cdrt Gprs Air Interface

8/3/2019 Cdrt Gprs Air Interface

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1 GPRS General Packet Radio Services

Air 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 Services


1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

2

Your Lecturer is:

Reiner Stuhlfauth

Rohde&SchwarzTraining Center, Munich





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

3

Structure of presentation

GPRS - Physical resource

GPRS - Logical channels

GPRS - Allocation of physical resource

Outline of Presentation





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

4

GPRS Radio InterfaceGPRS-

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

T

3

T3

T3

T3

T

3

T3

T3

T8

57 data bits 57 data bits26 BitsTraining Sequence

F1

F1

G8,25

G

8,25

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 the

same Burst types as

known from GSM





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 8,25

T

T = Tailbits F = Flagbits G = Guardtime

GPRS Radio Interface





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

6

0 1 2 3 4 5 6 7

Signalling: BCCH + FCCH + SCH + CCCH

Circuit switched channels Packet switched channels

PDCH

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 TCH

and 3 physical channels for packet switched PDCH

GPRS Capacity on Demand





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 TCHS 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:


GPRS PDCH: Traffic or signalling channel in packet switched mode

FN

S = SACCH

GPRS Physical Resource





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 TCHS 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:


GPRS PDCH:


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 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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

GPRS PDCH:


GPRS PDCH:



1 Radio Block

is the smallest

transport unit

in GPRS!

2 Radio Blocks

may belong to 2

different users!

=> sharing of

physical resources

Radio Block transmits signalling or data





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 physical

resource

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 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

12

GPRS: Additional Logical Channels

PBCCH

Signalling

and Control

Packet

Traffic Channels

PCCCH

PPCH

PRACH MS initiates uplink transfer

PAGCH Resource assignment to an MS

PNCH Notifying PtM Packet Transfer

Broadcast of packet data

specific information

PDTCH Packet Data Transfer; (multislot)

PACCH

DL

UL

DL

DL

DL

DL & UL

PTCH

Signalling: resource allocation,

acknowledgements, PC, TA, etc.

Paging MSs for packet dataand circuit switched services

PDCH: Packet Data Channel:





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

13


Logical Channel Comparison

CIRCUIT SWITCHED GSM PACKET SWITCHED GPRS

FCCH No Direct EquivalentSCH No Direct Equivalent

BCCH PBCCH

PCH PPCH

RACH PRACH

AGCH PAGCHNCH PNCH

SDCCH PCCCH/PACCH

TCH PDTCH

SACCH PACCH

SACCH PTCCHFACCH PACCH

CCCH PCCCH

PDCH





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

14


Channel 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

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

3 new channelcombinations in

GPRS





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

15

GPRS: Signalling Information

Signalling 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

Additional

GPRS-Info





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

16

GPRS: Signalling Information

Broadcast Control ChannelCommon Control Channels

Packet Broadcast Control

Channel

Packet Common Control

Channels

C o m p l e x i t y





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 GPRS

51-Multiframe: GSM-Signalling

26-Multiframe: GSM-Traffic

52-Multiframe: GPRS-Signalling and Traffic

GPRS + GSM Multiframes





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 NB

1 Radio Block = 4 TS in consecutive TDMA Frames

Uplink-Multiplexing:

PDTCH & PACCH

PDTCH, PACCH & PRACH

or

Downlink-Multiplexing:

PDTCH & PACCH

PDTCH & PACCH & PCCCH

incl. PBCCH

PDTCH & PACCH & PCCCH

without PBCCH

GPRS Multiframe





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 a

new logicalchannel in GPRS

PTCCH is a

new logicalchannel in GPRS





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

20


timeslot n timeslot n+1

Guard Period8,25 bit periods

Burst intimeslot n

Burst intimeslot n+1

PowerRamping

GSM Timing Advance and Guard Period





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

22


P T C C H / U p

l i n k

P T C C H / D

o w n l i n k

= 1 A c c e s s B u r s t

= 1 R a d i o

B l o c k = 4 N

o r m a l B u r s t

s

Packet Timing Advance Control Channel, PTCCH

MS sends Access Burst on uplink

Network sends Control Message on downlink





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

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

P T C C H / U p

l i n k

P T C C H / D

o w n l i n k

= 1 A c c e s s

B u r s t

= 1 R a d i o

B l o c k = 4 N

o r m a l B u r s t

s

MS has 2 possibilities within 52 Multiframe, but

network needs 4 Normal Burst to transmit the message!





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

24

GPRS Radio Interface52-multiframe num ber n:

uplink TAI=0 TAI=1

B0 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:

uplink TAI=2 TAI=3

B0 B1 B2 4 B3 B4 B5 5 B6 B7 B8 6 B9 B10 B11 7

downlink TA message 1 TA message 1


uplink TAI=4 TAI=5

B0 B1 B2 8 B3 B4 B5 9 B6 B7 B8 10 B9 B10 B11 11



uplink TAI=6 TAI=7

B0 B1 B2 12 B3 B4 B5 13 B6 B7 B8 14 B9 B10 B11 15



uplink TAI=8 TAI=9

B0 B1 B2 16 B3 B4 B5 17 B6 B7 B8 18 B9 B10 B11 19



uplink TAI=10 TAI=11

B0 B1 B2 20 B3 B4 B5 21 B6 B7 B8 22 B9 B10 B11 23




B0 B1 B2 24 B3 B4 B5 25 B6 B7 B8 26 B9 B10 B11 27


Operation of PTCCH on 52 Multiframe

C om

b i ni n g 8 t i

m e s t h e

5 2 M

ul t i f r a m e

t o g e t a P T C C H-M ul t i f r a m e





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

25

GPRS Radio Interface52-multiframe num ber n:

uplink TAI=0 TAI=1

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



uplink TAI=2 TAI=3

B0 B1 B2 4 B3 B4 B5 5 B6 B7 B8 6 B9 B10 B11 7



uplink TAI=4 TAI=5

B0 B1 B2 8 B3 B4 B5 9 B6 B7 B8 10 B9 B10 B11 11



uplink TAI=6 TAI=7

B0 B1 B2 12 B3 B4 B5 13 B6 B7 B8 14 B9 B10 B11 15



uplink TAI=8 TAI=9

B0 B1 B2 16 B3 B4 B5 17 B6 B7 B8 18 B9 B10 B11 19




B0 B1 B2 20 B3 B4 B5 21 B6 B7 B8 22 B9 B10 B11 23




B0 B1 B2 24 B3 B4 B5 25 B6 B7 B8 26 B9 B10 B11 27



TAI = Timing

Advance Identifier

to define the Frame,

where the MS is

allowed to transmit

one Access Burston the PTCCH/uplink





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

26


52-multiframe num ber n:

uplink TAI=0 TAI=1

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



uplink TAI=2 TAI=3

B0 B1 B2 4 B3 B4 B5 5 B6 B7 B8 6 B9 B10 B11 7



uplink TAI=4 TAI=5

B0 B1 B2 8 B3 B4 B5 9 B6 B7 B8 10 B9 B10 B11 11



uplink TAI=6 TAI=7

B0 B1 B2 12 B3 B4 B5 13 B6 B7 B8 14 B9 B10 B11 15downlink TA message 2 TA message 2


uplink TAI=8 TAI=9

B0 B1 B2 16 B3 B4 B5 17 B6 B7 B8 18 B9 B10 B11 19




B0 B1 B2 20 B3 B4 B5 21 B6 B7 B8 22 B9 B10 B11 23




B0 B1 B2 24 B3 B4 B5 25 B6 B7 B8 26 B9 B10 B11 27



Network transmits Timing Advance Control

Message with length of 4 Normal Burs ts

on PTCCH/Downlink





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

27

GPRS Allocation of physical resource

Allocation of physical

resource

fixed

dynamic

Extended

dynamic

Allocation of physical resources can be done belonging

3 different modes. Fixed and dynamic allocation is

mandatory, extended dynamic allocation is optional.





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

28

d o w n

l i n k

U S F R a d i o B l o c k

B ( n )

USF = R1

USF = R2

USF = R3

USF =R4

u p l i n k

R a d i o B l o

c k 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 Assignment

USF = Uplink State Flag

USF sent in downlink Radio Block points 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 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

29

d o w n

l i n k

U S F R a d i o B l o c k

B ( n )

USF = R1

USF = R2

USF = R3

USF =R4

u p l i n k

R a d i o B l o

c k 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 Allocation

USF = Uplink State Flag

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

numbered assigned PDCH’s





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

30


B9 B10 B11B6 B7 B8B3 B4 B5B0 B1 B2T X X

T

52 TDMA Frames

Timeslot Allocation0 1 2 3 4 5 6 700001011

Assigned TimeslotsBitmap example

Allocation Bitmap

010

111

000

110111

000

111

000

101

001

100

111


T


TN4

TN6

TN7

PDCH

= not assigned Radio Block = assigned Radio Block

example

GPRS Fixed Assignment





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

31



T

52 TDMA Frames



Allocation Bitmap

010

111

000

110111

000

111

000

101

001

100

111


T


TN4

TN6

TN7

PDCH


example


1. Element of fixed assignment:

Timeslot Allocation

Vector with 8 elements which

assigns the timeslots that may be

used by the MS for the data transfer





1MAT | 09.09.02 |

GPRS

Physical resource

GPRS

Logical channels

GPRS

Allocation of

physical resource

32



T

52 TDMA Frames



Allocation Bitmap

010

111

000

110111

000

111

000

101

001

100

111


T


TN4

TN6

TN7

PDCH


example


2. Element of fixed assignment:

Allocation Bitmap

Matrix with Nx12 elements:

12 lines, corresponding to the

12 Radio Blocks within the 52

Multiframe.

N columns, depending on the

N assigned timeslots with

the Timeslot Allocation Vector





1MAT | 09.09.02 |

GPRS

Physical resource

GPRSLogical channels

GPRS

Allocation of

physical resource

33

Mobile Originated Packet TransferMobile Originated Packet Transfer

MSNet-

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 One

Access

Phase Two

Access

(optional)

GPRS Packet Data Transfer





1MAT | 09.09.02 |

GPRS

Physical resource


GPRS

Allocation of

physical resource

34


Mobile originated data transfer:GPRS channel request

Channel request

via RACH

Packet Channel request

via PRACH

Single block establishment

One phase access request

One phase access request

or

Short access request

Two phase access request





1MAT | 09.09.02 |

GPRS

Physical resource


GPRS

Allocation of

physical resource

35


Network originated data transfer

Common Control Channels

Common Control Channels

Packet Common Control Channels

Packet switched paging

Circuit switched paging

Circuit switched paging

Packet switched paging

or





1MAT | 09.09.02 |

GPRS

Physical resource


GPRS

Allocation of

physical resource

36

Thank you for your attention

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http://www.rohde-schwarz.comor

[email protected]

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Cdrt Gprs Air Interface