THROUGHPUT MAXIMIZING FEEDBACK FOR MIMO OFDM BASED WIRELESS COMMUNICATION SYSTEMS

Currently evolving wireless communication systems (e.g. LTE-A, WiMAX) are based on linearly precoded MIMO OFDM and utilize adaptive modulation and coding to adjust the code rate and modulation alphabet to the current channel conditions. For this purpose the transmitter requires channel knowledge, which is provided by means of receiver feedback, utilizing the rank, precoding matrix and channel quality indicators. This work presents algorithms for computing these feedback values. Our algorithms choose the rank and precoding matrix indicators to maximize the estimated user throughput, whereas the channel quality indicator is chosen more conservatively to satisfy a given upper bound on the block error ratio. We demonstrate the performance of the proposed algorithms by means of link level simulations and comparison to theoretical bounds on the achievable throughput.