Generalized Network-Coded Cooperation in OFDMA Communications

Cooperative communication is a well-established technique to obtain diversity and consequently combat the fading inherent to the wireless channel. In a recent work, network-coded cooperation (NCC) along with graph theory-aided subcarrier allocation was applied to an OFDMA network where multiple source nodes have independent information to transmit to a common destination. In the so-called NCC-OFDMA scheme, diversity is then obtained by means of space and frequency, showing that the aforementioned scheme is capable of achieving improved diversity-multiplexing tradeoff (DMT) over other schemes presented in literature. In this paper, we present a generalization of the NCC-OFDMA scheme, where time dimension is also exploited to improve the DMT. Moreover, in our proposed scheme, referred to as generalized dynamic network coding-OFDMA, we show that the network performance (either in terms of DMT or energy effciency) can be increased even further by relaxing a constraint imposed to the NCC-OFDMA scheme that only a set of nodes is able to transmit redundant information.