Zte Params Gprs-edge

7/22/2019 Zte Params Gprs-edge

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Radio Network GPRS/EDGE Concept and

Parameters


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Introduction to GPRS

General Packet Radio Service

GSM Evolutionary Step

Interfaces

GPRS Network & Concept

Parameters


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GSM Evolutionary Steps


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GPRS Interfaces

Gf

D

Gi

C

E

Gp

Gs

Signaling and Data Transfer InterfaceSignaling Interface

MSC/VLRTE BSS

TEPDN

R Um

Gr

HLR

Other PLMN

GGSN

Gd

SM-SCSMS-GMSC

SMS-IWMSC

EIR

GnLAN SW /

IP BB

DNS CG LIG

Gn Gn

Gc

A

Gb

MT

SGSN SGSN GGSN

Gn

Gn Gn


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Why Gs and Gd interface:

Gs interface: Brings support of combined procedures (LAC /RAC

Updates, Attach) used for A and B type mobiles.

Avoids additional signalling load on the radio

interface.

Gd interface:

Gives the possibility to sent short messages (SMS)

via the SGSN.

Important decrease of radio signalling channel load


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Why Gs Interface:

BSS

MSC

SGSN GGSN

Internet

PSTN

GPRS

Backbone

IP Network

Gs Interface

Class B MS

GPRS attached

Circuit switched paging via GPRS

Speech call

Speech call


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GPRS Network & Concept- Overview

BTS BSC

MSC

SGSN GGSN Internet

PSTN

GPRS

Backbone

IP Network

GPRS Core

Shared GSM and

GPRS Infrastructure

GPRS Infrastructure IP World

Host

155.222.33.55

Host

131.44.15.3


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GPRS Entry Network and Network Elements

CG

DNS

SGSN

GGSN

LAN

switch

SS7

FR

Network

Internet or

Intranet

BG

Firewall

Inter-PLMN

network

(Legal

Interception

Gateway)

BSS

LIG

(Domain

Name Server)

(Charging

Gateway)

(GPRS GatewaySupport Node)

(Border Gateway)

(Serving GPRS

Support Node)

FirewallOMCFirewallFirewall


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GPRS Network Elements and Primary Functions

SGSN

Mobility Management

MS Authentication

Ciphering

Interaction with

VLR/HLR

Charging and

statistics

GGSN

Secure

interfaces toexternal

networks

Charging &

statistics

IP address

management

Charging

Gateway

CDR

consolidation

Forwarding CDR

information to

billing center

Border Gateway

Interconnects

different GPRS

operators'backbones

Enables GPRS

roaming

Domain Name Server

Translates IP host names to IP

addresses Makes IP network configuration

easier

In GPRS backbone SGSN uses

DNS to get GGSN and SGSN IP

addresses

Two DNS servers in the

backbone to provideredundancy

Legal Interception Gateway

Enables authorities to intercept

subscriber data and signaling

Chasing criminal activity Operator personnel has very

limited access to LI

functionality

LI is required when launching

the GPRS service


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BSC

BTS

Class C GPRS only(or manually switched between GPRS and speech modes)

Class B GPRS and Speech (not at same time)

(Automatically switches between GPRS and speech modes)

Class A GPRS and Speech at the same time

GPRS Mobile Terminal Classes


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GPRS Mobility Management

Mobile States

Idle"Off"

Standby"Idle"

Ready"Active"

Packet

TX/RX

STANDBY

Timer Expiry

GPRS

Attach/ Detach

READY

Timer Expiry

MS location known to

RA Level.

MS is capable of receiving

Point-to-Multipoint data

and being paged for

Point-to-Point data

MS location

not known.

Subscriber is not

reachable by the

GPRS NW.

MS location known toCell Level.

MS is transmitting or has

just been transmitting.

MS is capable of receiving

Point-to-Point data and

Point-to-Multipoint data.


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Connecting to the GPRS Network

Attach Request

Attach Accepted

GPRS Attach

Connects to the GSM network checking authentication and

updating mobile location.

Subscriber Information is downloaded from the HLR to the SGSN


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Establishing a PDP Context

Gets an IP address from the network

Initiated by the MS

Contains QoS and routing information enabling data transfer between

MS and GGSN

PDP (Packet Data Protocol)Context Activation

155.131.33.55

PDP Context Request


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PDP Context Activation - 1

Accessing the HLR

BTS BSC

SGSN

GGSN

Intranet

GPRS

BackboneIP Network

SS7

HLR

DNS

(1) MS sends "Activate

PDP Context Request" to

SGSN

Access Point Name

PDP Type (IP)

PDP Address (empty

== dynamic)

QoS & other options

APN (Access Point Name):

Reference to an external packet data

network the user wants to connect to

Internet

APN=

"Intranet.Ltd.com"

1.

2.

Access

Point

(2) SGSN checks against HLR Access Point Name Dynamic / static IP address QoS


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Finding the GGSN

BTS BSC

SGSN

GGSN

GPRS

Backbone

IP Network

DNS

DNS (Domain Name Server):

Workstation database to map logical names to IP

addresses

(1) SGSN gets the GGSN

IP address from DNS

APN maps to the

GGSN IP address

Intranet

Internet

1.

2.

Access

Point

(2) SGSN sends "Create PDP ContextRequest" to GGSN

PDP Type (IP) PDP Address (if empty=> dynamicaddress) Access Point Name QoS


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Access Point Selection

BTS BSC

SGSN

GGSN

GPRS

Backbone

IP Network

DNS

Access Point Name refers

to the external network the

subscriber wants to use

Physical/logical

interface in GGSN

Access Point configuration

in GGSN defines where to

connect the user

If a dynamic address is

requested, this is allocated

by the GGSN

Intranet

Internet

APN="Intranet.Ltd.com"


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PDP Context Activation - 4Context Activated

BTS BSC

SGSN

GGSN

GPRS

Backbone

IP Network

(1) GGSN sends "Create

PDP Context Response"

back to SGSN (2) SGSN sends "Activate

PDP Context Accept" to the

MS

SGSN now ready to route

user traffic between MS and

GGSN

Intranet

Internet

1.

2.


18/73

Link adaptation andGPRS Coding Schemes

CodingScheme

Payload (bits)per RLC block

Data Rate(kbit/s)

CS1 181 9.05

CS2 268 13.4

CS3 312 15.6CS4 428 21.4

More Data=

Less ErrorCorrection

Data

Error

Correction


19/73

Link Adaptation

Needed for selecting the optimum channel Coding Scheme (CS)for a particular connectionThe selection is based on channel quality estimatesHow it works:1. Collect measurements and make an estimate of the channel quality2. Compare the results with thresholds3. Make decision to change or maintain the current CS

The decision is done by statistical testing methods based onthe BLER measurements.


20/73

Impact of C/I on Throughput

0

5

10

15

20

25

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

C / I ( dB )

UserDataThrough

put(Kbit/s)

C S - 1

C S - 2

C S - 3

C S - 4


21/73

Radio interface summary for EDGE

In GSM, including GPRS, we are using GMSK modulation

In EDGE we have new modulation: 8-PSK

This modulation change allows higher data rates in air interface

Due to higher speed in air interface, modifications needed in A-bis

interface (dynamic A-bis pool, ADAP pool)

New re-sending algorithm: Incremental Redundancy (IR)

PCU orders BTS to send relevant RLC block indifferent MCS than

the original RLC block

Link adaptation: same idea than in GPRS, more steps (2 versus 9)


22/73

GPRS & EGPRS coding schemes

GPRS has four coding schemes,

CS-1...4. All use GMSK.

EDGE has nine modulation and coding

schemes, MCS-1...9.

MCS-1...4 use GMSK,

MCS-5...9 use 8-PSK modulation

Operator can set the MCS to start with

E.g. always start with MCS-9

MCS-7

MCS-1

22

MCS-2

28

MCS-3

37

MCS-4

44

MCS-5

56

MCS-6

74

5656

MCS-8

6868

MCS-9

74 74

redundancy from

channel coding

RLC data block,

number of octets

RLC/MAC block

(radio block)

CS-1

20

CS-230

CS-3

36

CS-4

50


23/73

Coding scheme Data rate for1 TSL

MCS-1 8.8 kbit/s

MCS-2 11.2 kbit/s

MCS-3 14.8 kbit/s

MCS-4 17.6 kbit/sMCS-5 22.4 kbit/s

MCS-6 29.6 kbit/s

MCS-7 44.8 kbit/s

MCS-8 54.4 kbit/s

MCS-9 59.2 kbit/s

Number of Abis TSLsThis is also requirement forGSM FR voice

2x2x2x2x3x4x5x5x

EGPRS Modulation and Coding Schemes


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GPRS mobile cell selection / reselection the same than theCircuit Switched idle mode cell selection

Cell is selected autonomously by the mobile

MS uses C1 and C2 parameters for cellselection/reselection (SYSTEM INFORMATION TYPE3)

GPRS handover is called as cell reselection

Cell reselection can be done during the data connection

GPRS Cell Selection and Reselection

C1

C2


25/73

GPRS optimization by Radio Network Planning

How can we optimize/improve GPRSperformance as Radio Network Planners:

Plan sufficient capacity/territory

Plan coverage/cell re-selection parameters fordominant coverage areas

On optimized GSM speech network is already well

optimized for GPRS from the radio performance point

of view


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Date post:	10-Feb-2018
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Zte Params Gprs-edge

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