TKN Technical Reports Series

In this report, proper frequency sub-band assignment and frequency guard band (GB) allocation is used to mitigate the effect of Multiple Access Interference (MAI), caused by synchronization offsets, in the uplink of OFDMA systems. This is done through formulation of an optimization problem, based on a solvable maximization of minimum user throughput. We can observe two main trade-offs. Firstly, if good frequency sub-bands is assigned to a badly-synchronized UT, the performance of that UT is improved but in the same time MAI on signals of other UTs is increased. Secondly, although MAI can be reduced by inserting GBs but inserting GBs implies the loss of resources and can lead to throughput loss due to this wastage. These two trade-offs are taken into account based on which a set of constraints for the optimization problem is defined. Adaptive coding modulation (ACM) is used to define the objective function of the optimization problem. The numerical evaluation of the proposed optimization algorithm shows an improvement of the minimum user throughputs by approximately 25 % compared to the the estimation and correction based technique. Suboptimal resource allocation problems are considered where it is shown that the solving time can be reduced significantly by chunking adjacent subchannels