3.5G(HSDPA)

High Speed Downlink Packet Access

By Ahmed Al-khaldi Ali bader Al-shaei Hassan Al-hassan

Overview

Why HSDPA?

HSDPA Features

• Hybrid Automatic Repeat Request

• Fast cell site selection

• Adaptive Modulation and Coding

HSDPA Terminals

HSDPA evolution

Conclusion

Why HSDPA?

Increasing bit rates in downlink.

Reducing delay ”TTI”.

Efficient users scheduling.

Simultaneaous single carrier

support for UMTS and R5 HSDPA

Why HSDPA?

Comparison Between 3G & 3.5G.

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

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

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

How HSDPA HSDPA Features

Decreasing delay due to transmission

errors

Hybrid Automatic Repeat Request

H-ARQ Schemes

Chase combining

Incremental Redundancy

Chase Combining

Data Block

Retransmissions

Block

Combine Accept Data

Block

Coding is applied to transmission packets

Soft combining of original and retransmitted signals is done at receiver before decoding

Advantage:

self decodable, time diversity, path diversity

Disadvantage:

wastage of bandwidth

Incremental Redundancy

Advantage:

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

Disadvantage:

non-self decodable

Data Block

Information from

IR database

Combine Error

Detection

IR Database

Accept Data Block

Error

No Error

Deliver

To Upper

Layers

How HSDPA HSDPA Features

Decreasing delay due to transmission

errors

Hybrid Automatic Repeat Request

Decreasing HO failure

Fast cell site selection

Fast cell site selection (FCS)

20 to 30% of UE on soft handover

Tracking of active set of Node B‘s connected to a UE

Selection of the Node-B with the best current transmission

characteristics

High data rates can be achieved

Additional Physical Channels

High Speed Physical Downlink

Shared Channel (HS-PDSCH)

• HS-Downlink Shared Channel

(HS-DSCH)

• HS-Shared Control Channel

(HS-SCCH)

High Speed Dedicated

Physical Control Channel (HS-

DPCCH)

How HSDPA HSDPA Features

Decreasing delay due to transmission errors

Hybrid Automatic Repeat Request

Decreasing HO failure

Fast cell site selection

Improving resources management

Stand alone downlink shared channel

Adapting to environment local features

Adaptive Modulation and Coding

AMC

Modulation Schemes:

• QPSK

• 16QAM

Code Rates used:

• 1/4, 1/2, 5/8 and ¾

HSDPA EVOLUTION

HSDPA Terminals

New terminals are required to take advantage of HSDPA:

• PC-cards will be the first on the market

• In the 1st phase terminals will offer:

Download 3,6 Mbps end user throughput

Upload 384 kbps

• Hand-held terminals will follow

• In a 2nd phase, peak data rates are increased to:

Download 14 Mbps

Upload 384 kbps

Conclusion

The most changing from 3G to the 3.5G is the

modulation.

More efficient implementation of interactive and

background Quality of Service (QoS) classes

Peak data rates exceeding 2 Mbps and

theoretically 10 Mbps & more with MIMO

Any questions ?