CDA EVM9 Manuale Utente Scaricare il pdf (Pagina 17)

Incremental Redundancy

The purpose of incremental redundancy is to increase throughput

by minimising the amount of redundant data sent OTA by:

• Only sending redundant data when necessary by use of ARQ

(Automatic Repeat Request) protocol

• Retransmitting more redundancy by transmitting the same

data with a different puncturing schemes

• Data is combined from original and retransmitted blocks to

increase likelihood of correctly decoding blocks

• MCS family groups are arranged such that data can be sent at

high MCS and retransmitted in parts at lower MCS

(retransmissions in GPRS must be at same CS)

Incremental Redundancy

•State diagram for IR

Data

Block

Error

Detection

ARQ

Error

Detection

Accept data

block

Block

in error

No error

Initial data

transmission

Block

in error

Transmit

At different

puncture

scheme or data

sub-block

No error

Deliver to upper layer

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 45 46

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CDA EVM9 Manuale Utente Pagina 17