A review of relay assignment problem in the cooperative wireless sensor networks

The relay selection is a promising approach of maximizing the diversity gain achieved in the cooperative wireless sensor networks. In the cooperative networks, the proper selection of relay node is a challenging task. The proper selection of relay nodes not only improves the source–destination performance, but also maximizes the overall system performance. There are many factors involved in designing a relay selection algorithm. The different relay selection algorithms have different focus, criteria, objective, mechanism, and performance issues. In this article, several relay assignment algorithms have been analyzed to show the effectiveness of channel capacity, power allocation, coverage expansion and interference mitigation in term of proper relay selection schemes. Moreover, this paper discusses some relay selection schemes, their challenging issues, limitations, performance criteria, and mechanisms. This article also highlights the significant design issues of relay selection methods and compares them that are appropriate in the cooperative wireless sensor networks.