Multi-degree random cyclic delay diversity in MISO systems with frequency-domain scheduling

Multi-carrier based radio access schemes have been widely accepted as the PRY technology of many standards. The promising of these schemes is due to their capability to combat multi-path propagation and support multiple user access through sub-carrier allocation as well. The performance of such a system depends on the frequency selectivity of the wireless fading channel. In order to increase the frequency selectivity, a cyclic delay diversity scheme is introduced where multiple antennas are used to create an artificial fading channel. Using a fixed cyclic delay, the original scheme is not ensured to be optimal in various circumstances. This paper presents a multi-degree cyclic delay diversity scheme where the delay values are randomly generated. With the aid of channel dependent user scheduling, the set of delay values which can achieve the best system performance are selected and utilized. Large performance enhancement is shown by means of simulation.