Adaptive cellular cyclic delay diversity for multi-carrier spread spectrum systems

The cell border area in a multi carrier spread spectrum (SIC SS) based system is influenced by large inter cell interference for a total frequency reuse in the neighboring cells. To handle this inter cell interference and to enable reliable soft handoff procedures, macro diversity techniques can be applied for these scenarios. Applying multi antenna transmit diversity techniques in a cellular environment, transmit diversity is transformed to macro diversity. In this paper, the cellular transmit diversity technique based on cyclic delay diversity (CDD), namely cellular CDD (C CDD), is further investigated in terms of adaptive transmit powers and proper choices of the cyclic delays. The adaption of these system parameters results in a broadened receiving diversity area and eliminates the performance degradation within the standard C CDD. Further, we show that the use of spread spectrum multi carrier multiple access (SS MC MA) exploits the scarce system resources in a more efficient way with almost the same or better performance compared to the well known multi carrier code division multiple access (MC CDMA) scheme.