Performance Enhancement of Low Granularity MIMO-OFDMA Using FSS Method

OFDMA is a technology that enables multiple users to share the same frequency band to achieve simultaneous multiple connections and high frequency utilization efficiency. Since the channel state of each user is different in multiuser environment, it is necessary to allocate optimal subcarrier (high granularity) to each user to maximize the frequency utilization efficiency. Furthermore, when we consider the MIMO-OFDMA, it is more difficult to choose the optimal subcarrier for each user. This is because the channel state of each antenna for an individual user is also different. Therefore, it is important to know in detail which subcarriers are used by each user, which increases the amount of control information and causes processing delay. Therefore, in practical 4G and 5G systems, subcarrier block assignment (low granularity) for each user is used. However, with considering the subcarrier block assignment, the received power is attenuated due to the effect of frequency selective fading, and this causes bit errors. To improve the BER performance and reduce the amount of control information, in this paper, we propose the optimum subcarrier block assignment for each user using FSS method for enhancement of multiuser diversity with reducing the control information [1] - [4] .