Kps Hsdpa (FINAL)

8/2/2019 Kps Hsdpa (FINAL)

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High Speed Downlink PacketAccess Trends and Techniques


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OUTLINE

INTRODUCTION What is HSDPA

Why HSDPA HSDPA evolution

HSDPA architecture

HSDPA key technologies

High speed channel extension

HS-DSCH


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HS-DSCH channel coding

HS-DPCCH

Structure of HS-DPCCH

HS-SCCH Physical layer operation procedure

AMC(Adaptive Modulation and Coding)

FCS(Fast cell site selection)

Fast scheduling in Node B HARQ(Hybrid automatic repeat request)

Fast retransmission


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Chase combing

Incremental redundancy

MIMO(Multiple input multiple output)

Conclusion.


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What is HSDPA?

High-Speed Downlink Packet

Access (HSDPA) is an enhanced 3G(third generation) mobile telephonycommunications protocol in the High-Speed Packet Access (HSPA) family,

also dubbed 3.5G, 3G+ or turbo 3G.
http://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/Mobile_telephonyhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/High-Speed_Packet_Accesshttp://en.wikipedia.org/wiki/High-Speed_Packet_Accesshttp://en.wikipedia.org/wiki/High-Speed_Packet_Accesshttp://en.wikipedia.org/wiki/High-Speed_Packet_Accesshttp://en.wikipedia.org/wiki/High-Speed_Packet_Accesshttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Mobile_telephonyhttp://en.wikipedia.org/wiki/3G


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Why HSDPA?

Comparison Between 3G & 3.5G.

Data Rate ( 2Mbps -----> 10 Mbps)

Modulation ( QPSK -----> QPSK&16QAM)

TTI( 10ms ----> 2ms )


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Comparison of data rates


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QAM constellations


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HSDPA Evolution


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HSDPA architecture-protocol stack


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HSDPA Key Technologies

High Speed Channel extension

Adaptive Modulation and Coding (AMC)

Fast packet scheduling at the Node B

Hybrid Automatic Repeat Request (HARQ)

MIMO


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High Speed Channel Extension

In UMTS Release99, DCH is the basic channel for voiceand data transmission (each user assigned one DCH),along with FACH and DSCH

HSDPA Channels:

New transport channel

HS-DSCH

New control channel

HS-SCCH

HS-DPCCH


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HS-DSCH

This is the pipe on which thepacket data are transmitted.


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HS-DSCH channel coding


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HS-DPCCH

High Speed Dedicated Physical ControlChannel (HS-DPCCH) was introduced in

the 3GPP release 5 of WCDMA as a newuplink code channel for controlpurposes.


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Structure of HS-DPCCH

HS-DPCCH carries the physical layerfeedback information


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HS-SCCH

Each HS-SCCH block has 3 slot duration, i.e. dividedinto 2 functional parts.

HS-SCCH Part-1:The first slot carries a important

time critical information.

HS-SCCH Part-2: The next 2 slots contain less timecritical parameters.


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The HS-SCCH uses SF 128 that can accommodate 40bits per slot.

It uses half rate convolution coding.


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Physical layer Operation Procedure


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Adaptive Modulation

HSDPA uses QPSK

16QAM


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Adaptive Modulation(Principle)


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Adaptive Modulation and Coding


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Fastcell site selection (FCS)Tracking of active set of Node Bs connected to a UE

Operate by monitoring SIR (Signal-to-Interference

Rate) level of all Bs

Selection of the Node-B with the best current

transmission characteristics

High data rates can be achieved


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Fast Scheduling in Node B

Scheduler algorithms (types of scheduler can beconfigured by operator per Node B):

Round Robin (RR)

Maximum carrier to interface(C/I)

Proportional fair(PF)


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H-ARQHybrid Auto Repeat reQuest

Provide Link Layer Retransmissions

Moved From RNC to Node-B

Use two Schemes:

Chase Combing

Incremental Redundancy


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Fast Retransmission

Fast Retransmit is an enhancementto TCP which reduces the time a sender

waits before retransmitting a lostsegment.
http://en.wikipedia.org/wiki/Transmission_Control_Protocolhttp://en.wikipedia.org/wiki/Protocol_data_unithttp://en.wikipedia.org/wiki/Protocol_data_unithttp://en.wikipedia.org/wiki/Transmission_Control_Protocol


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Fast Retransmissions


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Chase Combining

Data Block

RetransmissionsBlock

CombineAccept

Data Block

Coding is applied to transmission packets

Soft combining of original and retransmitted signals isdone at receiver before decoding

Advantage:self decodable, time diversity, path diversity

Disadvantage:

wastage of bandwidth


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Incremental Redundancy

Advantage:

Reducing the effective data throughput/bandwidth of auser and using this for another user

Disadvantage:

non-self decodable

Data Block

Information from

IR database

Combine ErrorDetection

IRDatabase

Accept

Data Block

Error

No Error

DeliverToUpperLayers


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Is based on multipath environment

Used just in downlink

Used in further away from the base

station

MIMOMultiple Input Multiple Output


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MIMO Principle with 2 transmitters and 2receiver antennas


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Conclusion

HSDPA evolution for WCDMA was introduced in Release 5

The most prominent change from 3G to the 3.5G is the

modulation technique.

It has more efficient implementation of interactive and

background Quality of Service (QoS) classes

It achieves Peak data rates exceeding 2 Mbps and theoretically 10

Mbps & more with MIMO

HSDPA improved also the performance of delay critical low bit

rate services like VoIP even though it was not originally designed

for it.


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Kps Hsdpa (FINAL)

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