Abstract:
With the rapid growth of multimedia services, future generations of cellular communications require higher data rates and more reliable transmission link with keeping satisfactory quality of service.
Cooperative communications have a great significant in modern communications as they improve the information transmission between the source and the destination by using the relays.
The relaying schemes are amplify-and-Forward (AF) and decode-and-Forward (DF). For AF the relay sends an amplified copy of its receive signal and consequently serves as a repeater. In contrast, for DF the relay performs a complete decoding of the receive signal and transmits the re-encoded message.
This thesis is a comprehensive study of cooperative systems, analyzing its performance and comparing the use of two protocols amplify and forward (AF) and decode and forward(DF) with single and multi relays scenarios by measuring bit error rate (BER) using Matlab simulator.
The result of comparison was showed that DF was better than AF protocol. At 2dB SNR, the BER is almost 0.07 in direct transmission while in multi relay DF is 0.003.The transmit diversity for AF is better than DF diversity at 20 dB is equal 2.5.
