It is highly expected that the new generation of wireless communication systems, offer much higher rate for voice, data and video services. In order to cope with increased worldwide demand for these services, communication systems with higher data rates, along with high reliability and user capacity are required. To overcome proposed MIMO system problems such as system complexity and financial issues, a new kind of diversity called cooperative diversity has been proposed. In cooperative relay networks intermediate nodes defined as relay nodes help a source to deliver its information to a destination. Using more than one available relay nodes in cooperative relay network instead of only one relay node, can cause some problems such as increasing system complexity, increasing the required bandwidth, or the need for accurate synchronization of symbols. In contrast opportunistic relaying or selecting one appropriate relay node from all active relay nodes can reduce energy consumption and increase data rates, in addition to the previous general cooperative relaying benefits, such as improving communication quality and coverage. In this thesis, the latest methods of relay selection or opportunistic relaying are left; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" align=left Keywords: Relay Selection, Cooperative Relaying, Amplify and Forward, Decode and Forward
