Performance Analysis of Cooperative Communication using Amplify and Forward Protocol

Abstract

With the rapid development of applications of wireless technology, future generation demands higher data rates and a more reliable transmission link while maintaining quality of service. In order to achieve these requirements, multiple-input multiple-output (MIMO) systems have been considered as an effective technique to meet these requirements by offering significant multiplexing and diversity gains over single antenna systems without increasing various parameters of wireless environment like bandwidth and power. Although MIMO systems results in very large benefits in cellular base stations, they may face problems when it comes to their implementation in mobile handsets. In particular, the typically compact-size of handheld devices makes it impractical to implement multiple antennas. To overcome this drawback, the concept of Cooperative Communications has recently been addressed and gained large interest in the research community. The main concept behind Cooperative Communication is to form a virtual MIMO antenna array by using a third terminal, a so-called relay node, which assists the direct communication. After receiving the source’s message, the relay processes and forwards it to the destination. With this approach, the benefits of MIMO systems can be attained in a distributed fashion. Furthermore, cooperative communications can efficiently combat the severity of fading and shadowing effects through the assistance of relay terminals. It has been shown that using the relay can extend the coverage of wireless networks. Different combining schemes and diversity protocols has been studied. In this thesis, the main focus is to evaluate the performance of Cooperative Communication systems using Amplify and Forward protocol. By using this approach second order diversity has achieved. A new transmission scheme is proposed in Cooperative Communication using Amplify and Forward protocol which results in high diversity gain that can overcome the drawback of noise amplification in Classical Cooperative Communication System using Amplify and Forward protocol.