training material_hsdpa principle

8/10/2019 Training Material_HSDPA Principle

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HSDPA Princ iple

-UMTS Radio Network Planning & Optimization Dept


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HSDPA Theory

HSDPA Physical Layer

HSDPA Key Technologies

HSDPA RRM

HSDPA Evolution

Contents


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HSDPAHigh Speed Downlink Packet Access

3G

4G

HSDPA is a new technology introduced in

R5 Goal: To provide a packet-oriented wireless broadband

access service with high performance price ratio, high

downlink bandwidth and short delay for WCDMA

3GPP R5 standards are frozen in June, 2006

Small modification to R99/R4 structure

HSDPA insists on the concept of smooth evolution.HSDPA is the enhancement of R99 structure with the

newly added MAC-hs layer to achieve HARQ,

scheduling and AMC. It also adds three dedicated

channels on the physical layer.

Improve the system capacity by applying

new technologies Share channel transmission-Fast Scheduling

Shorter TTI - Fast retransmission and soft

combination

Link Adaptive - Permitting High order modulation

HSDPA High Performance Price Ratio

Downlink peak rate of single cell: 14.4Mbps

Multi-user share of single cell, with 230

users in theory

Low costSmall modification to R99

Good technical

evolution of WCDMA


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HSDPA Protocol Stack

R99/R4

PHY

MAC

RLC

PHY L1

L2

DSCH

FP

L1

L2

DSCH

FP

MAC-

c/sh

L1

L2

DSCH

FP

L1

L2

DSCH

FP

MAC-d

RLC

Uu Iub Iur

UE Node-B CRNC SRNC

MAC-hs

PHY(3 new

CHs)

HS-

DSCH

FP

HS-

DSCH

FP

HS-

DSCH

FP

HS-

DSCH

FP

R5 HSDPA

MAC-hs

Uu: New additional 3 Physical layer

Channels, i.e.,HS-PDSCH

(Downlink Data), HS-SCCH

(Downlink Control Signalling), HS-

DPCCH (Uplink Control Signalling)

Additional MAC-hslayer

on Node-B (H-ARQ, AMC

and Scheduling etc)

Iub, Iur: HS-DSCH

FP (Downlink Data)


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HSDPA Newly Added Physical Channels

R99 Channel

HSDPA Channel

HS-PDSCHBearing HS-DSCHtransmitting HSDPA user data (DL)

It is a 2ms subframe with 3 slots, SF=16 and multiple codes permitted. HS-PDSCH

can use two modulations of QPSK and 16QAM.

HS-SCCHBearing the signaling information for demodulation of HS-PDSCH (DL)

It is a 2ms subframe with 3 slots and SF=128. HS-SCCH includes the information of modulation,

transport block size, UE identification, etc. It uses QPSK modulation.

HS-DPCCHBearing feedback information transmitted by downlink HS-DSCH (UL)

Includes Hybrid-ARQ ACK/NACK and Channel-Quality Indication (CQI). It is a 2ms subframe with 3

slots and SF=256. First slot is ACK/NACK and the following two slots are CQI.

HS-DPCCH

HS-PDSCH

HS-SCCHUE

DPCH

DCCH (Signaling) + UL DTCH (PS Service)

DL DTCH (PS Service)

CNUTRAN


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HS-PDSCH Physical Channel Structure

HS-PDSCH can use QPSK or 16QAM modulation. M is the bit represented by each

modulation symbol. For example, M=2 stands for QPSK and M=4 stands for 16QAM.

All layer1 signaling are transmitted by affiliated HS-SCCH. HS-PDSCH doesnt carry

any layer 1 signaling.

Slot #0 Slot#1 Slot #2

Tslot= 2560 chips, M*10*2 bits (k=4)

DataNdata1bits

1 HS-PDSCH subframe: T = 2 ms

HS-PDSCH Frame Format

Physical Channel Slot Format

Slot format

#1

Channel

BitRate

Channel

Symbol

Rate

SFBit/HS-DSCH

Sub-frameBits/Slot Ndata

0(QPSK) 480kbps 240kbps 16 960 320 320

1(16QAM) 960kbps 240kbps 16 1920 640 640


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HS-SCCH Physical Channel Structure

HS-SCCH adopts fixed code rate (60 kbps, SF=128), bearing the relateddownlink signaling for demodulation of HS-PDSCH

Slot #0 Slot#1 Slot #2

Tslot= 2560 chips, 40bits

Data

Ndata1bits

1 subframe: Tf= 2 ms

HS-SCCH Frame Format

HS-SCCH

HS-PDSCH

3Tslot7680 chips

HS-PDSCH (2Tslot 5120 chips)

3Tslot7680 chips

HS-DSCH sub-frame

Timeslot relation of HS-SCCH and HS-PDSCH

HS-PDSCH begins after HS-SCCH starting 2Tslot = 5120 chips


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HS-DPCCH Physical Channel Structure

HS-DPCCH carries the feedback signaling transmitted by downlink HS-DSCH. The feedback

signaling includes HARQ-ACK and CQI. Each 2ms subframe includes 3 slots with 2560 chips per slot, same as the normal DPCCH.

HARQ-ACK is at the first slot of HS-DPCCH subframe. CQI is at the second and third slots.

HS-DPCCH: SF=256, each slot has 10bits.

Normally one wireless link has a HS-DPCCH and it must exist with one certain uplink

DPCCH.

Subframe #0 Subframe #i Subframe #4

HARQ-ACK CQI

One radio frame T = 10 ms

One HS-DPCCH subframe (2 ms)

2Tslot= 5120 chipsTslot= 2560 chips

HS-DPCCH Frame Format

Slot

format #1

Channel

Bit Rate

Channel

Symbol RateSF

Bit/HS-DSCH

Sub-frameBits/Slot

Transmitted slot per

sub-frame

0 15kbps 15kbps 256 30 10 3

HS-DPCCH Slot Format


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HSDPA Newly Introduced Physical

Channels Timing Relation

HS-

PDSCH

HS-SCCH

HS-DPCCH (ACK/NACK and/or CQI)

HS-SCCH

2 TS 7.5 TS +/- 128 Chip N TS

1 TS = 2560 Chip

The starting point of first HS-

SCCH subframe is the same asthe starting point of P-CCPCH


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HSDPA Theory



HSDPA RRM

HSDPA Evolution

Contents


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HS-DSCH Transport Channel

Only exists on the downlink channel

Number of transport block always equals to 1

One HS-DSCH handle one CCTrCH, decoding from

one CCTrCH

One UE corresponds to the only one CCTrCH

CCTrCH can be mapping to one or several physical

channels

One CCTrCH has only one HS-DSCH

Always accompanying DPCH and one or moreshare physical control channels (HS-SCCHs) Quality balance of different HS-DSCH channels

Static data match (Two rate matches in HARQ

Transport block cascade

The number of transport block is 1 forever and as well as the number of transport

channel, and each CCTrCH only corresponds to one HS-DSCH, so the followingsdont exist:


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HS-DSCHs coding and multiplexing CRC check: same as normal CRC, 24bit in L1

Bit scramble: The bit after CRC check is scrambled by bit scrambler

Code block segment: same as R99, Turbo coding, Z=5114

Channel encode: same as R99, using 1/3 Turbo code

HARQ: Bits after adjusting channel encoding match with the total bits

mapping from HS-SDCH to HS-PDSCH

Physical channel segment: When using multiple HS-PDSCH, the

physical channels are segmented.

Interleave: progressed independently according to each physical

channel

16QAM constellation recomposition: This function is transparent to

QPSK

Physical channel mapping

CRC attachment

aim1,aim2,aim3,...aimA

Code block segmentation

Channel Coding

Physical channel

segmentation

PhCH#1 PhCH#P

Physical Layer Hybrid-ARQ

functionality

dim1,dim2,dim3,...dimB

oir1,oir2,oir3,...oirK

ci1

,ci2

,ci3

,...ci

E

vp,1,vp,2,vp,3,...vp,U

up,1,up,2,up,3,...up,U

w1,w2,w3,...wR

HS-DSCH

Interleaving


Constellation

re-arrangementfor 16 QAM

rp,1,rp,2,rp,3,...rp,U

Bit Scrambling

bim1

,bim2

,bim3

,...bimB

Bit scramble is to guarantee the synchronization of receiving

data and transmitting data, without introducing the time

deviation. Bit Scramble is to encrypt the data bits and it does

not change the bit length of the data.


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HARQ and Rate Matching

Systematic

bits

Parity 1

bits

Parity2

bits

RM_P1_1

RM_P2_1

RM_P1_2

RM_P2_2

RM_S

First Rate Matching Second Rate MatchingVirtual IR Buffer

Nsys

N

p1

Np2

Nt,sys

N

t,p1

Nt,p2

bitseparation

NTTI

bitcollection

N

data

C W

HARQ function block adjusts the bits after channel encoding and the total bits

mapping from HS-SDCH to HS-PDSCH to be matched. HARQ function block is controlled by the parameter of redundancy version (RV).

The output bits of HARQ function block is determined by input bits, output bits

and RV parameter.

HARQ function block is composed of two rate matcher and one virtual buffer

Fi t R t M t hi d S d R t


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First Rate Matching and Second Rate

Matching

The algorithm of first rate matching is almost the same with Rel99. Bits of

encoder output match with the bits of virtual IR buffer input. Virtual buffer

capacity NIRis given by the high layers. Encode bit NTTIis derived from the

high layer signaling and the signaling parameters of HS-SCCH of each TTI.

NIRNTTIthen first rate matching is transparent.

NIR


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HARQ Rate Matching and IR Method

During the second rate matching, the data set formed by punch are displayed by

different gray levelsDeep, Medium, Low

Deploy different RV and punch method when retransmitting data

When 16QAM is deployed, different RV methods correspond to not only different

punch methods but also different constellation versions or reforming.

IR buffer size 10bit

Raw data 4bit1/3 Turbo encoder


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HS-DPCCH Physical Procedure

HARQ-ACK/NACK encode10bit full 1 and full0

CQI encodeadopting (20, 5) code, 20bits CQI info bit encode

Create corresponding 030 total 31 CQI value

HS-DPCCH and other uplink channels make frequency spreading

in parallel. If the max. number of DPDCH is even, then HS-DPCCH

is mapping to route I, otherwise it is mapping to route Q.

HS of HS-DPCCH is derived from the power offset informed by

ACK, NACK and CQI


Channel CodingChannel coding

PhCH

b0,b1...b19


HARQ-ACK CQI

a0,a1...a4

PhCH

w0,w1,w,...w2 9

HARQ-ACK and CQI handle the encode in parallel

Doing multiplexing at different times

I

j

cd,1 d

Sdpch,n

I+jQ

DPDCH1

Q

cd,3 d

DPDCH3

cd,5 d

DPDCH5

cd,2 d

DPDCH2

cd,4 d

cc c

DPCCH

S

CHSHS-DPCCH(If Nmax-dpdch=odd)

DPDCH4

CHSHS-DPCCH(If Nmax-dpdch=even)

HS

r t t i n f r -CC

HS

r t t i n f r -CC

cd,6 d

DPDCH6


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HSDPA Introduced Key Technologies

AMC Fast Scheduling

16QAMFixed SF16, 2ms short frame

Shared channelHARQ

1 2

3 4

5 6

Adopt 2ms short frame, fixed SF, TDM

and CDM between the users at the

same time

Introduce 16QAM high order

modulation, providing higher

modulation efficiency

AMC makes the data transport well

adaptive to the changes of radiochannels

Fast scheduling makes multi-user

share the radio resource.

HARQ quickly adjust the channel rate

according to the status of radio link

and achieve the error correction and

retransmission of the data.

Shared channel makes the number of

access users not limited by the code

resources.


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Key Technology 12ms radio frame

Share channel resources are dynamically assigned in every 2ms

TTI

HARQ fast feedback retransmission based on 2ms TTI

2ms TTI makes scheduling response much faster and in time

10 ms

20 ms

40 ms

80 ms

Earlier releases

2 ms

Rel 5 (HS-PDSCH, HS-SCCH, HS-DPCCH)

sub-frames (2560 chips/slot, 3Slots)

Standard Frame length Channel feedback delay Remark

R99 10ms >100ms Scheduling feedback is in RNC

HSDPA 2ms 5ms

7.5 Slots

Continuous feedback supported,

R5 still support the 10ms frame

of R99

Decrease the loop time effectively, improve the link adaptive ability highly


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Key Technology 216QAM

HSDPA Modulation QPSK

16QAM


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Key Technology 3AMC

Modulation adaptiveGood channel condition: 16QAM

Bad channel condition: QPSK

Code efficiency adaptiveGood channel condition: code rate

Bad channel condition:1/3 code rate

Code channel number adaptiveGood channel condition: more code channels

Bad channel condition: less code channels

Full use of channel conditions to transmit user data effectively

Good channel condition: High user data rate transmission

Bad channel condition: Low user data rate transmission

The combination of different parameters such as modulation mode, coding

mode, number of code channels, size of transport block, RV matching has

thousands of configuration choice. This makes AMC technique higher

efficiently and more flexible.


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Key Technology 6Shared Channel

User1 User2 User3

DCH1

DCH2

DCH3

Shared

HS-DSCH

UMTS

R99

HSDPA

Saved for Other Users

Shared fat-pipe

10ms

TTI = 2ms TimeMultiplexing

Code Multiplexing

Dedicated

TTI: Transmission Time Interval


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Comparison of HSDPA and R99/R4Item R99 HSDPA

CapacityMbps 2.688 14.4

Frequency spectrum

efficiency (kbit/(MHz*Cell))537.6 2795.2

HandoverHard handover / Soft handover /

Softer handover / Intersystem handover (to GSM)Hard handover in HS-PDSCH

Power ControlOpen loop / Close loop / external loop

Fast speed/ Low speed

Low speed power control or no power

control in HS-PDSCH

Modulation QPSK QPSK16QAM

Link Adaptive Fast power control/ soft handoverAMCHARQshort frame and fast

channel feedback

Bit Scramble and

DescrambleN/A Only used in HS-PDSCH

MAC-hs N/A Used for fast scheduling

HSDPA

HSDPA is to adjust data rate

according to channel condition when

ensuring the power

Constant powerChanging

data rate

R99/R4

R99/R4 is to adjust power according

to channel condition when ensuring

service rate

Constant data rate, changing

power


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HSDPA Theory



HSDPA RRM

HSDPA Evolution

Contents


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RNC Radio Resource Management

Summary

Code resource management

HSDPA

channelization

code

HSDPA

scrambling code

Power resource management

HSDPA total power

resource management

Service amount measurement/

Dedicated measurement

Dynamic radio carrier control

Channel

Assignment

Channel

Handover

Access control

DPCH

channelization code

Channel

Handover

Mobile management

Congestion control

Load control

Handover

measurement

Power control

Physical channel power control

Load balance

Dedicated

measurement

R4

Common

Measurement

HSDPA

Common

Measurement

Assignment of HSDPA

resource for each cell

User resource assignment

and management


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Power Control

HSDPA Physical control includes: HS-PDSCH, HS-SCCH and HS-DPCCH

HS-PDSCH

Power control

HS-SCCH

Power control

HS-DPCCH

Power control

Support open loop power control, configuration

Measurement Power Offset

Support open loop and internal loop power control

HS-SCCH Power Offset can be dynamically adjusted

Support open loop and internal loop power control, configuration

ACK,NACKand CQIand can be dynamically adjusted according

to link status

HS-PDSCH and HS-SCCH dynamically adjust HS-PDSCH and HS-SCCH total power

according to the resource occupancy of system excluding HS-PDSCH and HS-SCCH.

For HS-DPCCH, its transmission power is determined by DPCCH. UE determine the

transmission power of HS-DPCCH according to gain factor HS.


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Access Control

Because HS-PDSCH physical channel is shared resource, access control of HSDPA is different than the access control

of dedicated channel.

During the access control, the characteristics of streaming, interactive, background services and the working feature of

HS-DSCH must be fully considered. The high speed feature of HS-DSCH shared channel must be fully developed during

the access control.

HS

DPA

Accesscontrol

UE support HSDPA

Number of HSDPA user

Power resource

Data throughput carried by HSDPA

DPCH channelization

code resource

AccessDecision

Node B support HSDPA


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HSDPA Channel Handover

HSDPA handover includes service cell change and channel

handover of HS-DSCH

Same frequency service cell change between Node B

First release the HS-DSCH resource of the old cell of source Node B, then

establish the same HS-DSCH resource as old cell in the new cell of Target

Node B.

Correspond to perform hard handover for HS-DSCH. The HS-DSCH transport

channel and radio carrier parameter do not change during the handover

procedure.

UE execute reassignment of physical channels. When the reassignment of

physical channel is valid, MAC-hs entity of UE needs to be reset and UE doesnt

receive HSDPA service channel.

The valid time of physical channel reassignment of UE corresponds to the valid

time of radio link reassignment of Node B. At the valid time, the MAC-hs entity

of Source Node B releases and the MAC-hs entity of Target Node B establish.

The two Node Bs are not transmitting at this time. So the service is interrupted

instantaneously during the reassignment time.

Same frequency service cell

change inside Node B

Similar with the change of same

frequency service cell inside

Node B

The difference is that only one

Node B are controlling. Thus

MAC-hs entity of Node B does

not change and MAC-hs entity of

UE does not need to be reset. But

the service is interrupted at the

valid time of physical channel

reassignment.


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Channel Handover Transfer Figure

1. Traffic Trigger

2. Transmission Power Trigger

3. Congestion Trigger

DCH

FACH

HS-DSCH

PCH

1. Traffic Trigger

2. Movement Trigger

1. Traffic Trigger

2. Movement Trigger

1.TrafficTrigge

r

1.TrafficTrigge

r

2.CongestionTrig

ger

1.TrafficTrigger

2.LoadTrigger

1.TrafficTrigger

3.CongestionTrig

ger

1. Traffic Trigger

1. Traffic Trigger

HS-DSCH

DCHHS-DSCH

FACH

HS-DSCH

PCH

DCH DCHDCH FACH

FACH PCH


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HSDPA Congestion Control HSDPA congestion control means how to mitigate resource congestion under the condition of HSDPA system

resource congestion.

The resource of HSDPA is shared and utilized in the maximum. Thus the method of congestion control isslightly different from R99 cell. HS-DSCH resource congestion includes:

Power resource congestion

Limited HS-DSCH traffic

Data through congestion

Code resource congestion of accompanying DPCH

channelization code

Congestion control method

of HSDPA

Occupy in advanceWhen resource is congested, the high-priority user can occupy the resource in advance from the

low-priority user. It guarantees high-priority user can be always assigned resources.

QueueThe users who has no ability to occupy in advance but has the queue ability can be put into the queue and try

to access the resource again.

Decrease loadThe policy of decreasing load is decreasing the speed. That is to decrease the rate of users who has

high background or interactive services for spare resources

HSDPA resource adjustmentAdjust the code resource or power resource of HSDPA to meet the requirements of users

Resourcecongestion

Occupy

in advance

Queue

Decreaseload

HSDPA

resource

adjustment

Improvecall

successrate,

Increasesystemcapacity


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HSDPA Load Control

Decrease usable power of HSDPAIts ultimate goal is decreasing the PS data throughput.

Decrease PS data throughputDecrease the PS data rate on DCH.

Delete macro diversity linkDecrease the radio link of overload cell to decrease the load.

Forced handover to another carrier or GSM systemInter-frequency handover and intersystem

handover can be used as the method for load transfer to decrease the load of overload cell.

Force some low-priority users to drop their calls.

The goal of load control is to guarantee the system stability.

If the system is appropriately planned, then the access control

and packet scheduling can avoid the overload of the resources

but can not avoid the situation that the system is overload

induced by suddenly user power increasing when the wireless

environment is deteriorated. Thus radio resource management

needs to adopt load control to let the system to be stable.

For the load control, the difference between HSDPA and R99 is only

at the downlink. Thus only the downlink load control method is

described here. The policy of decreasing load includes

Overload

Decrease overall power of

HSDPA

Decrease PS data throughput

Delete macro diversity link

Forced handover

Ensurethesystem

stability

I fl f HSDPA t R99 RRM


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Influence of HSDPA to R99 RRM

Algorithm By introducing HSDPA, the related HSDPA physical channels are

added. Thus R99 RMM algorithm is needed to be upgrade Add special handling of HS-PDSCH and HS-SCCH code resource

management

Add access control method of HS-DSCH

Add power control method of HSDPA

Add dynamic radio carrier control policy after introducing HS-DSCH

The introducing of HSDPA cell and handover characteristics of HSDPA

physical channel affect the mobile handover decision policy and handling.

Add load balancing characteristics for cells. Affect the selection of load

balanced destination cell and later handling, eg., accompanying the transfer

between HS-DSCH and DCH

Update in congestion control

Update in load control


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HSDPA Theory



HSDPA RRM

HSDPA Evolution

Contents


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Mobile Communication Development Mobile communication is developed from 2G3G3.9G. It is

developed from mobile voice service to high speed data service.Currently it is developed to 3.5G. For WCDMA, commercial R5

version and trial R6 version can be provided now.

3GPP is working on the standards of R7/HSPA+ and R8/LTE. It is

estimated that R7 will be finalized on 2007 and R8 will be finalized

on 2008.

The development of radio technology pays more attention to the

requirement of operator NGMN organization proposed the system

development goal.

M bil C i ti T h l
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Mobile Communication Technology

Evolution

2G 2.5G 3G 3.5G 3.75G 3.9G2.75G

GSMWCDMA

R99GPRS

EDGE

HSDPA HSUPA

HSPA+

LTE

IS-95CDMA2000

1X EV-DO

CDMA

2000 1X

EV-DO

Rev. A

EV-DO

Rev. BAIE

CDMA2000

1X EV-DV


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WCDMA Roadmap

GSM

GPRS/EDGE

3GR99

3G+HSDPADownlink

Enhanced

3G

HSDPA/HSUP

A

Downlink/UplinkEnhanced

GSM(GPRS/EDGE)

3G

Enhanced UMTS

Optimized UMTS

NGMN

NGMN

LTE,Broadband radio

IP based wideband

Peer to Peer

2002-3 2003-4 2005-6 2007-9 After 2009Year

DL

throughput

64-144kbps 64-384kbps 384kbps-4Mbps 384kbps-7Mbps 20-50Mbps


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