Cooperative Hybrid Automatic Repeat Request Based on the Number of Retransmissions

摘要

Cooperative communication has great potential to boost the wireless data rates by exploiting the antennas on wireless devices for spacial diversity. Since decode and forward (DF) approach eliminates noise accumulation problem, DF protocol is suitable for relay selection scheme. To improve the system performance turbo coding along with Hybrid Automatic Repeat Request (HARQ) technique is used where turbo coding adds redundant bits and HARQ minimizes the error rate in the system. The data is broadcasted over a Rayleigh fading channel. Maximal Ratio combining is used at the receiver to combine the information received from the source and the relay. If received data is found to be in error at the destination, then NACK is transmitted to the source. In this paper HARQ scheme for turbo coding is performed for different modulation order over Rayleigh channel in presence of Additive white Gaussian noise. The number of retransmissions required to clear total number of errors is calculated.