WiMAX/OFDMA Burst Scheduling Algorithm to Maximize Scheduled Data

OFDMA resource allocation algorithms manage the distribution and assignment of shared OFDMA resources among the users serviced by the basestation. The OFDMA resource allocation algorithms determine which users to schedule, how to allocate subcarriers to them, and how to determine the appropriate power levels for each user on each subcarrier. In WiMAX, the downlink (DL) TDD OFDMA subframe structure is a rectangular area of N subchannels times K time slots. Users are assigned rectangular bursts in the downlink subframe. The size of burst, in terms of number of subchannels and number of time slots, varies based on the user´s channel quality and data to be transmitted for the assigned user. In this paper, we study the problem of assigning users to bursts in WiMAX TDD OFDMA system with the objective of maximizing downlink system throughput for the Partially Used subcarrier (PUSC) subchannalization permutation mode. Our main contributions in this paper are: 1) we propose different methods to assign bursts to users, 2) we prove that our Best Channel burst assignment method achieves throughput within a constant factor of the optimal, 3) through extensive simulations with real system parameters, we study the performance of the Best Channel burst assignment method. To the best of our knowledge, we are the first to study the problem of DL Burst Assignment in the downlink OFDMA subframe for PUSC subchannalization permutation mode taking user´s channel quality into consideration in the assignment process.