GPRS Day 1_a.ppt

Mobile Communication Division RNE_Fund_18_06E01.ppt /Edition 01/

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GPRS Radio Network Planning

CS-3 coverage area

CS-4 coverage area

CS-2 coverage area

CS-1 coverage area

GPRS


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Content

Basics on GPRS

RNP relevant GPRS aspects



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1998 1999 2001 Time2000

GSMGSMDataData

HSCSDHSCSD

GPRSGPRS

EDGEEDGEEGPRSEGPRS

UMTSUMTS

Packet technology (GPRS)

Circuit switched technology (GSM)

SIM SIM ToolkitToolkit

WAPWAP

Technology for applications


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Bit rate

Technology

UMTS

2 Mb/s

384 Kb/s

EDGE

GPRS

160 Kb/s

64 Kb/s

HSCSD

1997 1998 1999 2000 2001 2002 2003

CS data - SMS, 9.6Kbits/s

9.6 Kb/s


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PacketPacketDataData

NetworkNetworkGPRS GPRS

BackboneBackbone

SGSN

GGSN

MSCHLR

TC

PublicPublicSwitchedSwitchedNetworkNetwork

A935 MFS

GbBSC

BTS

BTS

GSL


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Mobile statesMobile states

IDLE state No GPRS Mobile Management service performed. No location context in any GPRS node. (No paging)

STANDBY state Mobile is attached (GPRS Mobile Management done). CS and PS paging and MOC establishment is possible. Routing Area is known in SGSN (VLR)

READY (transferring) state Data has been received from MS, Cell based location is known MS may send and receive data in this state Timer (not data transfer !) keeps MS in this state after which it

reverts to standby


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"Idle" Attachment to network

Detachment

Out of Time

Packet Tx or Rx

Detach

ment o

r Out

of T

ime

«Ready»"Stand-by"

GPRS PrinciplesMobile states


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The AIR Interface


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In first Step: 1 TRX per cell with GPRSIn first Step: 1 TRX per cell with GPRS

PDCH PDCH (Packet Data Channel): new channel types to transmit data

One or several users can be multiplexed on one PDCH

CS and PS traffic is dynamically allocated

Data Packets are transmitted via a TBFTBF (Temporary Block Flow) identification

The AIR Interface: Logical Channels


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New logical Channel Types on Air Interface for GPRSNew logical Channel Types on Air Interface for GPRS(not in GPRS step 1)(not in GPRS step 1)

PCCCHPCCCH (Packet Common Control Channel) used to initiate packet transfer

PBCCHPBCCH (Packet Broadcast Control Channel) used for broadcasting system information

PTCHPTCH (Packet Traffic Channel) used for data transmission and associated signalling

PTCCHPTCCH (Packet Timing Advance Control Channel) used for continuous timing advance mechanism.

MPDCH MPDCH (Master Packet Data Channel) GPRS master channel. A PDCH is called MPDCH if it carries PBCCH and PCCCH

The AIR Interface: Logical Channels


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PDCHPDCH Frame Structure (1)

TDMA with 8 TS as for CS TS which is allocated with GPRS is named PDCH Several TS grouped are called PDCH group

Maximum PDCH per group is currently 8 Several Users can multiplexed block wise on one PDCH

The AIR Interface: Frame Structure


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PDCHPDCH Frame Structure (2)

12 Blocks form a 52 - Multiframe

1 Block include 4 TDMA - Frames

1 PDCH in 1 Block includes 4 timeslots with 114 bits each ( =456 bits / RLC block )

Brutto throughput rate is 456 bit/18.462ms = 24.7 kbit/s per timeslot theoretical value; will be reduced in cause of USF, Coding scheme etc.

The AIR Interface: Frame Structure


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RNP relevant GPRS aspects


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CS RLC data block (incl. header) [bytes] RLC data unit [bytes] RLC data unit throuput [kbit/s]

CS-1 22 20 8

CS-2 32 30 12

CS-3 38 36 14,4

CS-4 52 50 20

Protection of the data on the radio interface accordingfour different coding schemes


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Measurements

Downlink Measurement is transmitted from MS to MFS (level and

quality) Reporting period variable according Parameter (counting

received data blocks)

Uplink At each received block, level and quality are computed

(over 4 TDMA Frames) and sent to the MFS. The measurements are averaged.


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Power control

2 Possibilities : open loop and closed loop

As first step only implemented in UL as open loop configuration

MS regulates Power according to received level (same Pathloss is assumed for UL and DL)

Max. output power allowed for MS is transmitted on (P)BCCH


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RNP Design Thresholds

With decreasing radio link quality the effective data throughput is reduced due to retransmission.

For CS-1 the data throughput is 7kbit/s with a C/I ratio of 9dB. With an increasing C/I ratio the data throughput increases only little up to its maximum value of 8kbit/s (saturation point).

According to ETSI the reference performance point is defined by the point at which a BLER of 10% is reached. This reference performance point is below the saturation point and is indicated schematically for both coding schemes in . As soon as the C/I ratio is below this value, the retransmission significantly reduces the effective data throughput rate.


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RNP Design ThresholdsData throughput rates

0

4

8

12

16

20

3dB 7dB 11dB 15dB 19dB 23dB 27dB

C/I

kbit/s Design thresholds for TU3: The reference performance point is reached at a BLER 10%. The following data throughput rates can be achieved at this point:

CS-1: C/I=9dB => 7kbit/s (saturation: 8kbit/s max.)

CS-2: C/I = 13dB => 10.5kbit/s (12 kbit/s max)

CS1

CS2


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RNP Design Thresholds: C/I Values

TU 3 TU 50PDTCH C/I requirements at whichreference performance point is met

NO FH[dB]

IdealFH [dB]

NO FH[dB]

Ideal FH[dB]

CS-1 13 9 10 9

CS-2 15 13 14 13

USF C/I requirement

USF CS-1 19 10 12 10

Frequency hopping is recommended for the GPRS carrier.


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RNP Design Thresholds: Sensitivity

ETSI Level thresholds for the PDTCH in relation to Alcatel specific values

GSM 900 Packet switched (PDTCH)CS1 CS2

Circuitswitched

TU3 TU50/TU 50ideal FH

TU 3 TU50/TU50ideal FH

BTS sensitivity (normalBTS) ETSI

-104dBm

-104dBm

-104 dBm/-104 dBm

-104 dBm -100 dBm/-101 dBm)

BTS sensitivity (normalBTS)Alcatel value

-111dBm

-109dBm

-109 dBm/-109.5 dBm

-105 dBm -106 dBm/-106.5 dBm

MS sensitivity (class 4-5) ETSI

-102dBm

-102dBm

-102 dBm -102 dBm -98 dBm


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RNP Design Thresholds: Cell Ranges

CS-3 coverage area

CS-4 coverage area

CS-2 coverage area

CS-1 coverage area

GPRS coverage for different coding schemes

GPRS Day 1_a.ppt

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