Video-aware relay selection in single-carrier and OFDM wireless systems

In this paper we consider packetized video transmission in cooperative relay-based wireless networks. We propose algorithms for optimized relay selection that take into account the content of each specific video packet. Our first algorithm, that is designed for a narrowband flat-fading channel and single-carrier modulation, selects jointly the optimal relay and video packet for forwarding. Our next algorithm is an extension of our main idea for OFDM modulation that is suitable for frequency-selective fading channels. In this case in addition to optimized packet and relay selection, our algorithm also jointly selects the optimal power level for each subcarrier. The key benefit of our algorithms is that they are fully distributed since they require no explicit communication among the relays but they only use passively collected information. We perform an extensive evaluation of our algorithms for different system configurations.