Wireless Access with Smart Antennas and SDMA

One of the most important challenges with respect to wireless access is the limited capacity of the air interface which is due to the fact that the available transmission bandwidth is finite. Since the number of wireless subscribers is still growing rapidly and the desire for higher data rates is rising – partially due to an ever growing popularity of the Internet – a more efficient use of frequency resources is inevitable to meet future capacity needs. Space Division Multiple Access (SDMA) can be used to multiply the capacity given by conventional multiple access techniques such as FDMA, TDMA or CDMA. However, the actual capacity gain which can be achieved with SDMA is highly dependent on the SDMA channel assignment and on the considered scenario (propagation, user distribution, traffic, mobility). Therefore in this paper several channel assignment strategies for SDMA systems are discussed and the problem of modeling different scenarios is addressed. Additionally some simulation results on the performance of SDMA systems are presented.