Revisiting two-way channel: Opportunistic network coding scheduling in fading channels

For two-way relaying networks, it was proved that independent fading characteristics of each link has negative impact on network coding gain. We hence further investigate fading characteristic of the two-way links and find a deterministic threshold in theory on the scheduling between network coding broadcasting and one side forwarding transmission for digital network coding (DNC) in the downlink. Based on this observation, a new power allocation policy is proposed to improve the sum rate in the downlink. In addition, system stability are investigated and some explicit bounds on average queuing length at relay are derived. Finally, unequal slot assignment for each phase as well as the associated end to end throughput are investigated to combat bottleneck link effect.