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RE: stds-802-16-mobile: Channel Model



Dear David,

my starting points have been the 29r4 document and the TestiPHY (see http://wirelessman.org/tga/contrib/C80216a-02_102v2.zip). My goal is: to modify the TestiPHY sources of the transmitter and to make the receiver so to match them to 802.16e proposals.
My physical layer is OFDM based (no single carrier).
As channel model, I've implemented the ITU-R M-1225 one (Clarke model) and I've replaced the SUI channel model (implemented by D.S. Baum in 29r4) with it.

At this moment the received signal is strongly disturbed because of multipath and the performance (in term of "bit rate") are reduced of 50%: my goal is implement a (sub-optimal) equalizer so that performance are reduced of at the most 20-30%.

N.B.: I measure the performance simply evaluating the ratio between the correct received byte number and the transmitted byte number.

Could you tell me some information that help me, in my research?

At 19.03 10/11/2003 +0000, you wrote:
Cosimo
 
There are channel models for .16, known as SUI: Stanford University Interim models
I think the document is 29r2 from a couple of years ago.  This includes a MATLAB implementation
that is a good starting point.
 
Note that .16 isn't desparately good in terms of mobility, but I'd be interested to hear your views on that.
The .16e work is concerned with handover, but I don't think the expectation is that SS will move desparately quickly: others may disagree.
 
There is also plenty of work on channel models currently in 802.20: it would be worth checking that out.
 
Equalisers are clearly a significant element in the performance of an 802.16 system, but as this is a receiver function, there is (deliberately) no information in the standard on how to implement one, and this knowledge tends to remain company confidential.
 
Note, however, in the OFDM physical layers, the separate carriers are independent so long as the multipath does not exceed the Guard Interval.
 
If you were interested in single carrier PHY, then there are some notes about equivalence of the required equalisers with the transformations needed in OFDM.
 
Regards
 
David Castelow
 
The comments are personal and do not represent the views of Airspan Communications.
-----Original Message-----
From: Cosimo Palazzo [mailto:cosimo.palazzo@unile.it]
Sent: 10 November 2003 16:39
To: stds-802-16-mobile@ieee.org
Subject: stds-802-16-mobile: Channel Model

Dear members,

I'm an undergraduate student of the University of Lecce (Italy): I'm doing a research about the TCP performance in the wireless environment.

I'm studying a network composed by more wireless networks (little range networks like 802.11e, and big range networks like 802.16e) that are connected together.

In this moment I'm trying a channel model for each wireless section of my scenario of study. My goal is to formulate a Markovian channel model (or similar) to simulate the activity of 802.16e in urban environment; the BS is fixed but the SSs are mobile (vehicular velocity, 20-80 Km/h).

In this moment I'm making a Matlab implementation of the physical layer for 802.16e. My problem is the choice of the equalizer block at the receiver: could you tell me some information about the state-of-art of this choice? Which equalizer will be proposed for 802.16e draft?
Could you tell me where I can find Matlab sources (or similar) for this equalizer?

Thanks in advance.

Cosimo Palazzo (Università degli Studi di Lecce - Italy)