Rate Control for Sum-Rate Maximization in Wireless Network Coding

For maximizing the benefit of network coding in two-way relay networks, the data rate of links from sources to a relay should be the same, since only the same number of received bits can be network-coded at a given time and the rate for broadcast at the relay is limited by the minimum rate over all links. Therefore, we investigate rate control scheme based on power control to maintain the link to be symmetrical while maximizing sum of data rates. We show the impact of rate asymmetry and formulate such problem as a max-min rate optimization problem. A simple iterative solution based on binary search algorithm is provided. Numerical results show the radio resource utilization in terms of bit/sec/Hz/watt is maximized by the proposed rate control scheme when the network coding is applied.