2. source gprs radio network juni 2010

8/12/2019 2. Source GPRS Radio Network Juni 2010

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GPRS Radio Network

By Subur Hendro SubektiBy Subur Hendro Subekti1414 JuniJuni20102010


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BackgroundBackground

When a GSM MS generates a data packet, the network forwards it

on the first available radio channel. One radio channel can be sharedamong several MSs. Depending on its capabilities, an MS can use

up to eight downlink time slots and eight uplink time slots simultaneously.

Data packets from an MS can also use different radio channels through the GSM radio network.

In WCDMA Systems, all MSs in a cell transmit and receive data over the same frequency.

The timeslot structure to separate the MSs does not exist; instead, they are distinguished

by codes assigned to them.

Different data rates are possible depending on the length and structure of these codes.For information on supported packet data transmission rates.

2G AREA2G AREA

3G AREA3G AREA


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GSM Cellular Network StructureGSM Cellular Network Structure


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WCDMA Cellular Network StructureWCDMA Cellular Network Structure


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Both the GSM and WCDMA Systems radio networks have a cellular stBoth the GSM and WCDMA Systems radio networks have a cellular structure,ructure,

but they do not share nodes. The GSM radio network includes GSMbut they do not share nodes. The GSM radio network includes GSM RBSsRBSs andand BSCsBSCs,,

while the WCDMA Systems radio network includes WCDMA Systemswhile the WCDMA Systems radio network includes WCDMA Systems RBSsRBSs andand RNCsRNCs..

The cellular structure for GSM and WCDMA Systems can be similarlThe cellular structure for GSM and WCDMA Systems can be similarly illustrated.y illustrated.

The main difference is that in GSM the sizes of the cells are stThe main difference is that in GSM the sizes of the cells are static,atic,

while in WCDMA Systems they are dynamic.while in WCDMA Systems they are dynamic.

The Service Areas are divided intoThe Service Areas are divided into PLMNsPLMNs. Each operator providing GPRS services. Each operator providing GPRS services

has its own PLMN. Nevertheless, to enable shared networks one SGhas its own PLMN. Nevertheless, to enable shared networks one SGSN can be sharedSN can be shared

by severalby several PLMNsPLMNs. A PLMN is identified by the Mobile Country Code (MCC). A PLMN is identified by the Mobile Country Code (MCC)

and the Mobile Network Code (MNC).and the Mobile Network Code (MNC).

An SGSN area, which consists of one or more RAs, is the region sAn SGSN area, which consists of one or more RAs, is the region served by the same SGSN.erved by the same SGSN.

It is either a GSM SGSN area, a WCDMA Systems SGSN area, or bothIt is either a GSM SGSN area, a WCDMA Systems SGSN area, or both (in a SGSN (WG)).(in a SGSN (WG)).An SGSN area does not have to coincide with an MSC/VLR area.An SGSN area does not have to coincide with an MSC/VLR area.

An SGSN pool area is the region served by a pool ofAn SGSN pool area is the region served by a pool of SGSNsSGSNs..


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Current Architecture

A RA, either a GSM RA or a WCDMA Systems RA, is an area which isA RA, either a GSM RA or a WCDMA Systems RA, is an area which is served by a given SGSN.served by a given SGSN.

One SGSN can handle several RAs. An MS may move between RAs withOne SGSN can handle several RAs. An MS may move between RAs with the SGSN areathe SGSN area

without roaming to a new SGSN. The size of an RA can range fromwithout roaming to a new SGSN. The size of an RA can range from a part of a city to ana part of a city to an

entire province, or even a small country. An RA consists of oneentire province, or even a small country. An RA consists of one or more cells.or more cells.A cell, either a GSM cell or a WCDMA Systems cell, is the smalleA cell, either a GSM cell or a WCDMA Systems cell, is the smallest geographical unitst geographical unit

in the GPRS service area. It is the basic unit of a mobile celluin the GPRS service area. It is the basic unit of a mobile cellular network and islar network and is

covered by one RBS. GSM cells are covered by a GSM RBS and WCDMAcovered by one RBS. GSM cells are covered by a GSM RBS and WCDMA SystemsSystems

cells are covered by a WCDMA Systems RBS.cells are covered by a WCDMA Systems RBS.

The size of a GSM cell is static, but can vary from cell to cellThe size of a GSM cell is static, but can vary from cell to cell. When expecting many users. When expecting many users

per unit area, a geographically small cell is preferable, when eper unit area, a geographically small cell is preferable, when expecting few users,xpecting few users,

a geographically large cell is preferable. A cell change in GSMa geographically large cell is preferable. A cell change in GSM can be visible tocan be visible to

the packetthe packetswitched part of the GSM networkswitched part of the GSM network

The size of a WCDMA Systems cell is dynamic and can change depenThe size of a WCDMA Systems cell is dynamic and can change depending on load,ding on load,Therefore, cell planning differs between GSM and WCDMA Systems.Therefore, cell planning differs between GSM and WCDMA Systems.

A cell change is not visible to the WCDMA System networkA cell change is not visible to the WCDMA System network


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2G GPRS

Air Interface Technology


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GSM GPRS PDCH Allocation (1)GSM GPRS PDCH Allocation (1)

SGSN

Air Interface

(Um)

Abis

BTS

BSC

MS

RPP (eric)/PCU

Gb

ALOCATION TIME SLOT ON BTS CAN BEDEDICATED PDCH

or ON-DEMAND PDCH DEPEND ON BSC CONFIGURATION

BCCH SDCCH PDCH

0 1 2 3 4 5 6 7

TRX-1

TCH

8 9 10 11 12 13 14 15

TRX-2

2 TRX


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SGSN

Air Interface

(Um)

Abis

BTS

BSC

MS

RPP (eric)/PCU

Gb

BCCH SDCCH PDCH

0 1 2 3 4 5 6 7

TRX-1

TCH

8 9 10 11 12 13 14 15

TRX-2

TCH

16 17 18 19 20 21 22 23

TRX-3

TCH

24 25 26 27 28 29 30 31

TRX-4

TCH

32 33 34 35 36 37 38 39

TRX5

TCH

40 41 42 43 44 45 46 47

TRX-6

ALOKASI DI BSC SBB :

1 BCCH use 1 TS1 CBCH use 1/8 SDCCH23 SDCCH

44 TCH

1 TS = 8 SDCCH/8

(1 CBCH + 23 SDCCH)/8 = 3 TS

DIBAGI DALAM 1 CGRPCGRP=0 6TRX

2 PDCH GPRS DEDICATED

MAXIMUM 8 TS USE CS-4

GPRS can carry data speeds up to 171,2GPRS can carry data speeds up to 171,2 kbit/skbit/sfor 8 timeslots use CSfor 8 timeslots use CS--44

GSM GPRS PDCH Allocation (2)GSM GPRS PDCH Allocation (2)


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GPRS Coding Scheme (1)GPRS Coding Scheme (1)

GPRS Coding Scheme

TS 1 2 3 4 5 6 7 8

CS1 9.05 18.10 27.15 36.20 45.25 54.30 63.35 72.40

CS2 13.4 26.80 40.20 53.60 67.00 80.40 93.80 107.20

CS3 15.6 31.20 46.80 62.40 78.00 93.60 109.20 124.80

CS4 21.4 42.80 64.20 85.60 107.00 128.40 149.80 171.20

kecepatan dalam Kbps


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GPRS Coding Scheme (2)GPRS Coding Scheme (2)

2 TS1 TS 4 TS3 TS 6 TS5 TS 8 TS7 TS

180 kbps

160 kbps

140 kbps

120 kbps

100 kbps

80 kbps

60 kbps

40 kbps

20 kbps

0 kbps

CS-1

CS-2

CS-3

CS-4


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2G EDGE



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What is EDGEWhat is EDGE

EDGE atau Enhanced Data Rates for GSM Evolution

merupakan evolusi GSM

EDGE sering di sebut EGPRS (Enhanced GPRS)atau IMTSC (IMT Single Carrier)

Generasi EDGE di sebut juga 2.75G

Kecepatan EDGE tiga kali lebih besar dari GPRS

Tujuan pengembangan EDGE :

peningkatan kecepatan transmisi data

peningkatan kapasitas

GPRS 171,2 Kbps

EDGE 384 Kbps (473,6 Kbps)


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GPRSGPRS vsvs EDGEEDGE

GPRS EDGE

Kecepatan 115 Kbps (teori 171,2

Kbps)

Teknik modulasi GMSK

(Gausian Minimum Shift Keying)

Dikenal 4 teknik pengkodean CS1

CS4

Tidak dapat melakukan resegmentasi

paket data

Kecepatan 384 Kbps (teori 473,6

Kbps)

Teknik modulasi 8PSK

(Phase Shift Keying)

Dikenal 9 teknik pengkodean MCS1

MCS9

Dapat melakukan resegmentasi

Paket data karena ada header(Penyesuaian Paket)


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EDGE ModulationEDGE Modulation

8PSK8PSK sebuahsebuah symbolsymbol dikodekandikodekan dengandengan 3 bit (GMSK 1 bit)3 bit (GMSK 1 bit)

TingkatTingkat symbol GMSKsymbol GMSK samasama dengandengan 8PSK8PSK yaituyaitu 270270 ksymbol/sksymbol/s,, sehinggasehingga tingkattingkat

modulasimodulasi 8PSK8PSK menjadimenjadi 3 kali3 kali lebihlebih besarbesar GMSKGMSK yaituyaitu 810 kb/s810 kb/s

JarakJarak antarantar symbolsymbol didi 8PSK8PSK lebihlebih pendekpendek daridari GMSK,GMSK, karenakarena 8PSK8PSK adaada 8 symbol8 symbol

sedangkansedangkan GMSKGMSK hanyahanya 2 symbol2 symbol

MakinMakin pendekpendekjarakjarak antarantar symbolsymbol mengakibatkanmengakibatkan tingkattingkat sinyalsinyal antarantar satusatu symbolsymbol

dengandengan symbolsymbol lainnyalainnya sukarsukar dibedakandibedakan,, sehinggasehingga kemungkinankemungkinan terjadinyaterjadinya

kesalahankesalahan lebihlebih besarbesar

PerbedaanPerbedaanjarakjarak antarantar symbolsymbol sangatsangat berpengaruhberpengaruh padapada saatsaat kondisikondisi sinyalsinyal radioradio

yangyang burukburuk,, sehinggasehingga butuhbutuh extra bitextra bit untukuntuk koreksikoreksi kesalahankesalahan

CS1CS1 CS4CS4 menggunakanmenggunakan modulasimodulasi GMSK.GMSK.

d l d d h ( )


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EDGE Modulation and Coding Scheme (MCS)EDGE Modulation and Coding Scheme (MCS)

GMSK11.2MCS2

GMSK8.80MCS1

GMSK17.6MCS4

GMSK14.8MCS3

8PSK29.6MCS6

8PSK22.4MCS

5

8PSK59.2MCS9

8PSK54.4MCS

8

8PSK44.8MCS7

ModulationSpeed

(kbit/s/slot)

Modulation and Coding

Scheme

EDGE can carry data speeds up to 236,8EDGE can carry data speeds up to 236,8 kbit/skbit/sfor 4 timeslotsfor 4 timeslots

(theoretical maximum is 473.6(theoretical maximum is 473.6 kbit/skbit/sfor 8 timeslots)for 8 timeslots)

GMSK21.40CS4

GMSK15.60CS3

GMSK13.40CS2

GMSK9.05CS1

GPRS

EDGE ll2G GPRS PDCH All i


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EDGEEDGE 2G GPRS PDCH Allocation2G GPRS PDCH Allocation

SGSN

Air Interface

(Um)

Abis

BTS

BSC support EGPRS

MS

RPP (eric)/PCU

Gb

BCCH SDCCH PDCH

0 1 2 3 4 5 6 7

TRX-1

TCH

8 9 10 11 12 13 14 15

TRX-2

TCH

16 17 18 19 20 21 22 23

TRX-3

TCH

24 25 26 27 28 29 30 31

TRX-4

TCH

32 33 34 35 36 37 38 39

TRX5

TCH

40 41 42 43 44 45 46 47

TRX-6

ALOKASI DI BSC SBB :

1 BCCH use 1 TS1 CBCH use 1/8 SDCCH23 SDCCH

44 TCH

1 TS = 8 SDCCH/8

(1 CBCH + 23 SDCCH)/8 = 3 TS

ForEDGE4x64kbps=256kbps

DIBAGI DALAM 2 CGRPCGRP=0 1 TRX (BCCH)

CGRP=1 5 TRX NON BCCH

4 PDCH EGPRS MENEMPATI DI CGRP=0

PDCH GPRS DITEMPATKAN DI CGRP=1

EDGE can carry data speeds up to 236,8EDGE can carry data speeds up to 236,8 kbit/skbit/sfor 4 timeslots use MCSfor 4 timeslots use MCS--99


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3G WCDMA


WCDMA R di A M d (1)WCDMA R di A M d (1)


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WCDMA Radio Access Mode (1)WCDMA Radio Access Mode (1)

WCDMA R di A M d (2)WCDMA R di A M d (2)


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WCDMA Radio Access Mode (2)WCDMA Radio Access Mode (2)

C t A hit tCurrent Architecture


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Current ArchitectureCurrent Architecture

Radio Network Functionality (1)Radio Network Functionality (1)


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The power control regulates the transmit power of the terminal aThe power control regulates the transmit power of the terminal and basend base

station, which results in less interference and allows more userstation, which results in less interference and allows more users on the sames on the same

carrier. Transmit power regulation thus provides more capacity icarrier. Transmit power regulation thus provides more capacity in the network.n the network.

POWER CONTROLPOWER CONTROL

WCDMA has a fast power control that updates power levels 1500 tiWCDMA has a fast power control that updates power levels 1500 timesmesevery secondevery second

Power control also gives rise to a phenomenon calledPower control also gives rise to a phenomenon called cell breathingcell breathing..

When the number of subscribers in the cell is low (low load), goWhen the number of subscribers in the cell is low (low load), good quality canod quality can

be achieved even at a long distance from the base stationbe achieved even at a long distance from the base station

On the other hand, when the number of users in the cell is high,On the other hand, when the number of users in the cell is high, the largethe large

number of subscribers generates a high interference level and sunumber of subscribers generates a high interference level and subscribersbscribers

have to get closer to the base station to achieve good qualityhave to get closer to the base station to achieve good quality



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Soft and softer handoverSoft and softer handoverWith soft handover functionality the handset can communicate simWith soft handover functionality the handset can communicate simultaneously with twoultaneously with two

or more cells in two or more base stations. This flexibility inor more cells in two or more base stations. This flexibility in keeping the connection openkeeping the connection open

to more than one base station results in fewer lost calls, whichto more than one base station results in fewer lost calls, which is very important to theis very important to the

operator.operator.The difference between soft and softer handover is that during sThe difference between soft and softer handover is that during soft handover, theoft handover, the

handset is connected to multiple cells at different base stationhandset is connected to multiple cells at different base stations, while during softers, while during softer

handover, the handset is connected to multiple cells at the samehandover, the handset is connected to multiple cells at the same base station.base station.



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Handover to GSM (interHandover to GSM (intersystem handover)system handover)


can be triggered by coverage, capacity or service requirementscan be triggered by coverage, capacity or service requirements

InterInterfrequency handover (intrafrequency handover (intrasystem handover)system handover)The need for interThe need for interfrequency handover occurs in high capacity areas wherefrequency handover occurs in high capacity areas where

multiple 5 MHz WCDMA carriers are deployedmultiple 5 MHz WCDMA carriers are deployed

Channel type switchingChannel type switching

The two most basic ones are common channels and dedicated channeThe two most basic ones are common channels and dedicated channels.ls.

Channel type switching functionality is used to move subscribersChannel type switching functionality is used to move subscribers between thebetween the

common and the dedicated channel, depending on how much informatcommon and the dedicated channel, depending on how much information theion thesubscriber needs to transmit.subscriber needs to transmit.

The dedicated channel is used when there is much information toThe dedicated channel is used when there is much information to transmit,transmit,

such as a voice conversation or downloading a web page. It utilisuch as a voice conversation or downloading a web page. It utilizes the radiozes the radio

resources efficiently as it supports both power control and softresources efficiently as it supports both power control and soft handover.handover.The common channel, on the other hand, is less spectrum efficienThe common channel, on the other hand, is less spectrum efficient. Onet. One

benefit is that the common channel reduces delays as many subscrbenefit is that the common channel reduces delays as many subscribers canibers can

share the same resource. Hence it is the preferred channel for tshare the same resource. Hence it is the preferred channel for the transfer ofhe transfer of

very limited information.very limited information.



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Admission controlAdmission controlThe admission control functionality is used to avoid system overThe admission control functionality is used to avoid system overload and to provideload and to provide

the planned coverage. When a new subscriber seeks access to thethe planned coverage. When a new subscriber seeks access to the network, admissionnetwork, admission

control estimates the network load and based on the new expectedcontrol estimates the network load and based on the new expected load, theload, the

subscriber is either admitted or blocked outsubscriber is either admitted or blocked out

Congestion controlCongestion control

Even though an efficient admission control is used, overload mayEven though an efficient admission control is used, overload may still occur, which isstill occur, which is

mainly caused by subscribers moving from one area to another aremainly caused by subscribers moving from one area to another area. If overloada. If overloadoccurs, four different actions can be taken. First, congestion coccurs, four different actions can be taken. First, congestion control is activated andontrol is activated and

reduces the bit rate of non realreduces the bit rate of non realtime applications, to resolve the overloadtime applications, to resolve the overload

Second, if the reduced bit rate activity is not sufficient, theSecond, if the reduced bit rate activity is not sufficient, the congestion control triggerscongestion control triggers

the interthe inter

or intraor intra

frequency handover, which moves some subscribers to less loadedfrequency handover, which moves some subscribers to less loaded

frequenciesfrequencies

Third, handover of some subscribers to GSM and forth action is tThird, handover of some subscribers to GSM and forth action is to discontinueo discontinue

connections, and thus protect the quality of the remaining conneconnections, and thus protect the quality of the remaining connectionsctions



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SynchronizationSynchronization

One of the basic requirements when WCDMA was standardized was toOne of the basic requirements when WCDMA was standardized was to avoid dependenceavoid dependence

on external systems for accurate synchronization of base stationon external systems for accurate synchronization of base stations. This has been achieveds. This has been achieved

by a mechanism, where the handset, when needed, measures the synby a mechanism, where the handset, when needed, measures the synchronization offsetchronization offsetbetween the cells and reports this to the network. In addition,between the cells and reports this to the network. In addition, there is also an option to usethere is also an option to use

an external source, such as GPS, for synchronizing the nodes, i.an external source, such as GPS, for synchronizing the nodes, i.e. to always provide the beste. to always provide the best

solution both asynchronous and synchronous nodes are supportedsolution both asynchronous and synchronous nodes are supported

Basic Architecture Concept RNCBasic Architecture Concept RNC


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Basic Architecture Concept RNCBasic Architecture Concept RNC

The Serving RNC has overall control of the handset that is conneThe Serving RNC has overall control of the handset that is connected to WCDMA Radiocted to WCDMA Radio

Access Network. It controls the connection on theAccess Network. It controls the connection on the IuIu interface for the handset and itinterface for the handset and it

terminates several protocols in the contact between the handsetterminates several protocols in the contact between the handset and the WCDMA Radioand the WCDMA Radio

Access NetworkAccess Network

The Controlling RNC has the overall control of a particular setThe Controlling RNC has the overall control of a particular set of cells, and their associated baseof cells, and their associated base

stations. When a handset must use resources in a cell not controstations. When a handset must use resources in a cell not controlled by its Serving RNC, thelled by its Serving RNC, the

Serving RNC must ask the Controlling RNC for those resources. ThServing RNC must ask the Controlling RNC for those resources. This request is made via theis request is made via the IurIur

interface, which connects theinterface, which connects the RNCsRNCs with each other. In this case, the Controlling RNC is also saidwith each other. In this case, the Controlling RNC is also said

to be a Drift RNC for this particular handset. This kind of opeto be a Drift RNC for this particular handset. This kind of operation is primarily needed to beration is primarily needed to be

able to provide soft handover throughout the network.able to provide soft handover throughout the network.

RAB (Radio Access Bearer)RAB (Radio Access Bearer)


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To establish a call connection between the handset and the baseTo establish a call connection between the handset and the base station a RAB isstation a RAB is

needed.needed.

Its characteristics are different depending on what kind of servIts characteristics are different depending on what kind of service/information to beice/information to be

transported.transported.

The RAB carries the subscriber data between the handset and theThe RAB carries the subscriber data between the handset and the core network. It iscore network. It is

composed of one or more Radio Access Bearers between the handsetcomposed of one or more Radio Access Bearers between the handset and the Servingand the Serving

RNC, and oneRNC, and one IuIu bearer between the Serving RNC and the core network.bearer between the Serving RNC and the core network.

3GPP has defined four different quality classes of Radio Access3GPP has defined four different quality classes of Radio Access Bearers:Bearers:

Conversational (used for e.g. voice telephony)Conversational (used for e.g. voice telephony)

low delay, strict orderinglow delay, strict ordering

Streaming (used for e.g. watching a video clip)Streaming (used for e.g. watching a video clip)

moderate delay, strict orderingmoderate delay, strict ordering Interactive (used for e.g. web surfing)Interactive (used for e.g. web surfing)

moderate delaymoderate delay

Background (used for e.g. file transfer)Background (used for e.g. file transfer)

no delay requirementno delay requirement



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Both the Conversational and StreamingBoth the Conversational and Streaming RABsRABs require a certainrequire a certain

reservation of resources in the network, and are primarily meantreservation of resources in the network, and are primarily meant forfor

realrealtime services. They differ mainly in that the Streaming RABtime services. They differ mainly in that the Streaming RAB

tolerates a higher delay, appropriate for onetolerates a higher delay, appropriate for oneway realway real

timetime

services.services.

The Interactive and BackgroundThe Interactive and Background RABsRABs are so calledare so called best effortbest effort, i.e. no, i.e. no

resources are reserved and the throughput depends on the load inresources are reserved and the throughput depends on the load in thethecell. The only difference is that the Interactive RAB provides acell. The only difference is that the Interactive RAB provides a prioritypriority

mechanism.mechanism.

The RAB is characterized by certain Quality of Service (The RAB is characterized by certain Quality of Service (QoSQoS) parameters,) parameters,

such as bit rate and delay. The core network will select a RAB wsuch as bit rate and delay. The core network will select a RAB withithappropriateappropriate QoSQoS based on the service request from the subscriber, andbased on the service request from the subscriber, and

ask the RNC to provide such a RAB.ask the RNC to provide such a RAB.


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THANK YOUTHANK YOU

2. source gprs radio network juni 2010

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