Opportunistic network coding for secondary users in cognitive radio networks

摘要

In cognitive radio networks (CRNs), secondary users (SUs) may employ network coding to pursue higher throughput. However, as SUs must vacate the spectrum when it is accessed by primary users (PUS), the available transmission time of SUs is usually uncertain, i.e., SUs do not know how long the idle state can last. Meanwhile, existing network coding strategies generally adopt a block-based transmission scheme, which means that all packets in the same block can be decoded simultaneously only when enough coded packets are collected. Therefore, the gain brought by network coding may be dramatically decreased as the packet collection process may be interrupted due to the unexpected arrivals of PUs.