Comparison of Space-Time Block Coding and Cyclic Delay Diversity for a Broadband Mobile Radio Air Interface

In this paper, we apply two different types of space-time block codes (STBC) in the downlink of a broadband mobile radio air interface based on MCCDMA, which is a promising candidate for a 4 generation mobile radio system. The first type are ”STBCs from orthogonal designs”. For 2 TX-antennas, this is the wellknown ”Alamouti”-scheme. These STBCs are compared to a different type, called cyclic delay diversity (CDD), which can be considered as STBC. Compared to STBCs of the first type, CDD can be applied with an arbitrary number of TX-antennas. Furthermore, no modification at the receiver is necessary, if the number of TX-antennas is changed. Simulations show the bit error performance of different TX/RX-antenna configurations for both STBC approaches, where, in fact, CDD performs mostly worse than STBCs from orthogonal designs, but with explicit complexity advantages.