On the duality between array beam-formers and MU-MISO precoders

Multi-user transmission, whereby users share time and frequency resources has been an active research area in the past decade in which the uniform linear array (ULA) was proposed and implemented for its model simplicity and easy implementation. This paper studies the performance of different methods used in ULA environment and their implication to multiuser multi-input single-output (MU-MISO) scenario where the channel is considered AWGN and Rayleigh fading (slow flat fading channel). The noise power level and the effect of multipath are investigated based on the assumption that the paths have the same loss exponent and the same length (i.e. the power of the received signal are the same from different paths). The results show that the best method dependent on numerous variables, the most important being the signal to noise ratio (SNR) and the number of multipath received from each source. The implementation of these methods in MU-MISO environment reveals that they can be successfully adopted for MU-MISO. It is observed that any method applicable to ULA scenario, is also applicable to MU-MISO scenario.