Optimal Tone Space Selection Scheme for OFDMA-VTS in Carrier Aggregation

In this paper, we propose an optimal tone space selection scheme for orthogonal frequency division multiple access with variable tone spaces (OFDMA-VTS) in carrier aggregation based on user-specific channels. We begin by analyzing inter-symbol interference (ISI) and inter-carrier interference (ICI) in non-contiguous carrier aggregation, which differ according to the delay and Doppler spreads associated with each user, as well as the tone space that each user utilizes. Based on that, we propose an optimal tone space selection scheme as a way to minimize both ISI and ICI. We also derive an upper bound on OFDMA-VTS capacity when it is applied to the proposed scheme. Furthermore, we investigate the effect of inter-user interference (IUI) in contiguous carrier aggregation and show that the proposed scheme can be applied to OFDMA-VTS in contiguous carrier aggregation as a suboptimal solution. Numerical results demonstrate that the proposed scheme maximizes OFDMA-VTS capacity by minimizing the total ISI and ICI interference, thereby enhancing the system capacity over what is possible with conventional OFDMA.