An Adaptive Power and Bit Allocation Algorithm for Multiple User MIMO OFDM System Employing Zero-Forcing Multi-user Detection

Abstract

This paper describes an adaptive algorithm for power and bit allocations in a multiple user Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO OFDM) system operating in a frequency selective fading channel. The zero forcing (ZF) technique is applied to accomplish multi user detection (MUD). The proposed adaptive algorithm employs a Lagrange multiplier method, which provides an optimal solution for power and bit allocations in one step. This is of considerable advantage in comparison with alternative algorithms, such as the greedy algorithm, that require time-consuming iterative procedures. The simulation results for both perfect and partial channel state information (CSI) available to transmitter show that the algorithm operates successfully in multiple user access scenarios without scarifying power and diversity gain.