Performance enhancement of cooperative networks using relay selection techniques

Abstract

In recent years, the demand of wireless communication systems has led to rapid development of new wireless technologies. The deployment of these emerging technologies will generate complex inter and intra network topologies, which will require cooperative mechanisms to enhance achievable capacity and transmission reliability. In this regard, it becomes imperative to study the impact of cooperative diversity techniques and its impact on system performance parameters, such as Symbol Error Rate(SER). This thesis focus on the performance improvement of cooperative networks by the use of relay selection and path selection schemes. In this thesis, firstly, a comparative analysis of different cooperative networks has been presented. Secondly, this work focuses on investigation of different relay selection schemes for various fading channels such as Rayleigh, Nakagami-m and Rician using different relaying protocols (Amplify and Forward, Decode and Forward), modulation schemes (BPSK and QPSK) and diversity combining techniques. A novel fuzzy logic based relay selection scheme is presented which achieves better performance in terms of SER and link reliability when compared with existing schemes. Over SNR range of 0-14dB, the fuzzy scheme reduces SER by an order of at least 10. Thirdly, using the aforementioned fading models a new metric for path selection in a Multi-Hop cooperative communication network is also presented. This path selection metric is based on the cumulative channel gain between the source and destination. Over SNR range of 0-14dB, this path selection scheme reduces SER by an order of at least 2.