Throughput, Energy and Overhead of Multicast Device-to-Device Communications with Network Coded Cooperation

Cooperation strategies in mobile networks typically rely in short range technologies, like LTE-A Device to Device (D2D) communications, for data exchange between devices forming mobile clouds. These communications provide a better device experience since the clouds offload the network. Nevertheless, this assumes that the throughput gains and energy savings in multicasting are much larger between devices than the base station to the receivers. However, current mobile networks suffer from many different issues varying the performance in data rates, which calls into question these assumptions. Therefore, a first objective of this work is to assess the operating regions where employing cooperation results in higher throughput and/or energy savings. We consider multicast scenarios with network coded mechanisms employing Random Linear Network Coding (RLNC). However, although RLNC is good for low amount of transmissions in multicast, it has
an inherent overhead from extreme high or low field related caveats. Thus, as a second objective, we review and propose the application of new network codes that posses low overhead for multicasting, by having a short representation and low dependence probability. We provide an analytical framework with numerical results showing: (i) gains of several fold can be attained even if the in-device data rates is moderately larger (2x) than the cellular link data rate and (ii) that is feasible to attain less than 3% total mean overhead with the proposed codes. This is fairly lower than what can be achieved with
RLNC schemes in most of the considered cases and achieving at least 1.5-2x gains.