[e2e] HARQ

L.Wood@surrey.ac.uk L.Wood at surrey.ac.uk
Mon Aug 27 05:37:45 PDT 2007

See http://en.wikipedia.org/wiki/Hybrid_ARQ


Saratoga: http://www.ee.surrey.ac.uk/Personal/L.Wood/dtn/

<http://www.ee.surrey.ac.uk/Personal/L.Wood/><L.Wood at surrey.ac.uk>

-----Original Message-----
From: end2end-interest-bounces at postel.org on behalf of Detlef Bosau
Sent: Mon 2007-08-27 9:23
To: end2end-interest list
Subject: [e2e] HARQ
Hi to all.

I have some HARQ issues, I do not fully understand.

First of all, there are three kinds of HARQ. I do not fully understand 
the difference between HARQ Type 1 and ordinary ARQ (without a buzzy H 
in the beginning).

The other two types are incremental redundancy and chase combining. Is 
this correct?

Now, HARQ often comes with adaptive channel coding.

To my understanding, chase combining requires any sending attempts for 
one PDU to be coded identically, in particular the MSCS/PS must not be 
changed for different sending attempts for the same PDU, although the 
channel properties may change in between.

Another concern is whether we have are restricted to a stop and wait 
scheme with IR / Chase combining. I don´t know a possibility to use 
sliding window here, because a receiver must know, which received Frames 
belong to the same original PDU.

This is particularly important as I´ve learned that in HSDPA the RLC 
endpoints are the RNC and the UE.
So, there is a transport line (Iub) between RNC and BS introduces 
storage capacity into the path and which makes the use of a stop´n wait 
scheme here questionable.

Can someone help me out here?


Detlef Bosau                          Mail:  detlef.bosau at web.de
Galileistrasse 30                     Web:   http://www.detlef-bosau.de
70565 Stuttgart                       Skype: detlef.bosau
Mobile: +49 172 681 9937

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