help!cooperative communication!

cooperative communication

hi,all.
i have some questions about the cooperative communication, since there is some formulas puzzle. if you do some research about cooperative communication, could you give me your email adress. i will send the question to you.
thanks

It would be nice if you put your question on the group.

hi all
here is my question. in Dr.lanmean's paper'Cooperative diversity in wireless networks. Efficient protocols and outage behavior' some relay protocols were proposed. all of them could get the full diversity in the high SNR, except the decode-and-forward protocol, it said the reason is "becasue requiring the relay to fully decode the source information limits the performance of decode-and-forward to that of direct transmission between the source and relay." here i can not understand why the perfromance of the link between S and R could make the diversity gain is only one. can anyone explain it? thanks

This is a good question.

anybody has some answers to it ?

hi there,
from my understanding, a typical decode-n-fwd(DF) suffers from error prpagation if the decoder fails, n hence, the scheme can't achieve divesity order as desired. There are few journals working on improving this technique soft DF bySneessens, adaptive DF by Fricke..

You mean, sometime relay can decode and sometimes not..

the net results is:

diversity order 1 or diversity order 2 ????

please reply!!

Hi all,
sorry for the late response.

as a friend has answered before, Decode and forward depends upon the quality of channel between the sender and the relay. If the channel is good enough such that the relay can correctly decode the signal, decode n forward gives 2nd diversity order because the relay regenerates/reproduces the signal(eliminating the errors induced by source-relay channel).

a bad source-relay channel causes the relay to incorrectly decode the signal at relay. The errors from source-relay channel cannot be eliminated and the signal gets further corrupted on the second leg of the journey i.e. relay-destination channel. Hence the performance is reduced and a diversity order of 1 is yielded.

i hope that answers the question.

I need PhD thesis

""Wireless cooperative systems"" by Paul A Anghel-
University of Minnesota, 2005.

if somebody has it, please share it, I would be thanking you.

Hi,
Maybe over a direct contact?:
Paul Anghel (University of Minnesota) anghel@ece.umn.edu

On the optimum power allocation in interference-free cooperative systems

We consider an interference-free fixed wireless cooperative system where transmissions from different terminals are orthogonal. In the proposed system the idled terminals help a source by relaying its information signal to the destination. We consider both regenerative and non-regenerative idled terminals (relays). For the inference-free system with non-regenerative relays, we show that maximizing mutual information for each user under total power constraint is a strictly quasi-concave maximization problem whose global optimal solution can be found efficiently. In fact, we provide a simple analytic formula for the optimum power allocation strategy, which is reminiscent of the water-filling principle. We also illustrate how the setup can be extended in order to allow for terminal mobility. For the regenerative system we consider two cases - full collaboration between relays and no-collaboration between relays - and show that in both cases the maximum mutual information under total power constraint can be found in polynomial-time.
K.

I tried email addresses

anghel@ece.umn.edu
and
panghel@ece.umn.edu

but the email was bounced back with the message

undelivered
Your message was not delivered to the following recipients:

Again, I would request if someone is from that univeristy or has the copy of this thesis please share it.

In cooperative communications where the relay repeating the message of other mobile using separate time fraction.

We get diversity gain, but this is also a fact that we are loosing degree of freedom, that is, time.
Instead of sending two separate messages in two times, we are sending one message in two times.

I mean, though we gain something but we lose as well,

How to evaluate that or how to quantify that loss ???

any idea!!!!!!!

Hi

To quantify this loss, two way relaying can use.