TECHNOLOGY Comparison of different Combining methods and Relaying Techniques in Cooperative Diversity

An ad-hoc network with a sender, a destination and a third station act-ing as a relay is analyzed . The channels are modeled containing thermal noise, Rayl eigh fading and path loss. Different combining meth ods and diversity protocols are compared. The amplify and f orward protocol shows a better performance than the decode and forward protocol, unless an error correcting code i s simulated. To combine the incoming signals the ch annel quality should be estimated as well as possible. Informatio n about the average quality shows nice benefits, an d a rough approximation about the variation of the channel qu ality increases the performance even more. What-ever combination of diversity protocol and combining method is used second level diversity is observed. The relative distances between the relay and the stations has a large effect on the performance.The aim of this pro ject was to study the characteristics and utility of relaying i n future wireless systems. The focus was mainly on the cooperative principles and relay selection in the case of mobil e multihop relay structures. This project also incl uded the study of IEEE 802.16j, the multihop relay specification for 802.16 or Wimax standard. It was an interesting ass ignment to study the practical realization of a concept that h as evolved over a couple of years. I studied some r elevant research papers (listed in the references section), modeled some simulation scenarios based on the results of t hese papers and gained a invaluable insight on some of the topics.