Joint optimization of resource allocation and modulation coding schemes for unicast video streaming in OFDMA networks

In the paper, we investigate a distortion-optimized resource allocation problem among a group of users with unicast video transmission in OFDMA networks. Since video distortion results from both encoding errors due to rate limitation and transmission errors due to packet losses, to minimize distortion we also consider joint optimization of the selection of the modulation and coding scheme (MCS) for each allocated resource unit. To proceed, we formulate a mixed-integer non-linear programming (MINLP) problem for joint resource allocation and MCS selection with the objective to minimize overall video distortions from all users. To solve the formulated problem, we propose a two-stage algorithm, where the Hungarian algorithm is used in the first stage to optimally assign the minimum resource units required for individual users based on their channel conditions. In the second stage, additional resource units are assigned to the most needed users with the greatest potential to minimize the overall distortions. As more resource units are allocated to each user, the MCS is adjusted accordingly to avoid biased selection from the initial resource unit. Simulation results show that the proposed algorithm achieves performance gain of about 16%-55% compared to the conventional approach of separate resource allocation and MCS selection.