Reconfigurability to antenna correlation: System level performance enhancements in HSDPA

The system level performance of an HSDPA MIMO network, which combats the effects of antenna correlation by applying novel reconfigurable techniques, is investigated. The impact of antenna correlation on adaptive array techniques has been thoroughly investigated and it has been shown that fading correlations reduce MIMO channel capacity and system performance. Nevertheless, considerable capacity and performance gains can be obtained by transmission on the eigen-modes of the transmit antenna correlation matrix. Reconfigurability to antenna correlation is achieved at the link level by applying a linear precoding scheme at the transmitter space-time block encoder, which is based on the well known Alamouti scheme. The linear precoder is determined so as to minimise a given criterion, such as an upper bound on the pairwise error probability (PEP) of a codeword. An appropriate link to system interface has been developed, taking into account the linear precoding technique. The system level performance metrics of interest are the average system and user throughput as well as the satisfied users. Simulation results are presented in order to demonstrate the performance enhancements achieved by the application of reconfigurable techniques compared to the conventional ones.