Cooperative diversity for Wimax: Practical schemes for scheduling and scheme selection

I found this nice paper that proposes methods and ways to deal with cooperative diversity scheme selection and radio resource allocation that could be used in the 802.16j standard which is still under development.
http://www.sce.carleton.ca/~furuzan/files/papers/wcnc08-bc.pdf

Since it is high time now to decide the exact nature of the project, I realized that it is also important to have a presentable model and some simulation results apart from just gaining knowledge by reading theory. This paper provides a useful guiding example for designing my own model.

Some brief overview of this paper is as follows:

1. Considers two hop network and uses OFDMA PHY for multiple access.
2. Relays are decode and forward type.
3. All cooperative diversity schemes use only one relay to realize diversity
4. Relaying schemes could be one of the following:
i) No relays (direct transmission)
ii) Relay used without diversity (just to improve coverage)
iii) Relay used with cooperative diversity (Several different flavors of this are used: refer to the paper for more details)
iv) Adaptive diversity (combination of the above)


The choice of a particular diversity scheme depends on the calculations done using the instantaneous SNRs in the BS to MS and RS to MS channels. A look up table helps to speed up the calculations. It also considers opportunistic scheduling of the users based on instantaneous SNRs.

The system model assumes practical modulation schemes, subchannel allocations, symbol times, coherence times, etc (details skipped here), Rayleigh fading is considered for all the channels and it is flat fading due to OFDMA.

The simulation results are plotted as the comparative gains of different diversity schemes in directional graph for a single cell with single base. An example of such a graph is shown above.

My first task will be modelling a similar system using suitable tool (Qualnet?). I am still not sure as to what details I should look at. However a simplistic model should be a good starting point. I would like to also evaluate the performance of diversity schemes with more than one relay and combine the process fo relay selection with all of this so that we get the maximum throughput.