Optimized adaptive modulation with considering mobile relay on FSS-OFDM system

This paper proposes an adaptive modulation on frequency symbol spreading (FSS) based orthogonal frequency division multiplexing (OFDM) relay system with considering the mobility of relay node. Wireless communications often suffer from large propagation loss due to shadowing and multipath fading. As a solution to this problem, Relay communications, which forward data messages from source to destination via intermediate station(s), have been focused on. It can obtain the space diversity and expand the area coverage. However, here arises an another issue on relaying how to deploy relay nodes in an efficient manner. In this paper, we present a whole system design of FSS-OFDM employing an adaptive modulation considering mobility of relay node. Exploiting a good match of an adaptive modulation and FSS, throughput performance can be significantly improved. Computer simulation verifies its effectiveness and reveals the proposed system is the most valuable means which realizes the flexible relay node deployment.