kps hsdpa (final)
TRANSCRIPT
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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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