Design of superimposed training sequence for spatially correlated multiple‐input–multiple‐output channels under interference‐limited environments

In this study, the design of a superimposed training (ST) for an interference‐limited spatially correlated multiple‐input–multiple‐output (MIMO) system is addressed and a closed‐form solution for designing the training signal is proposed in a sub‐optimal way. Earlier papers have considered noise limited MIMO systems. The authors also propose random/orthogonal variable spread factor (OVSF) codes as a choice for the ST signal. The mean‐squared error of the channel estimate and symbol error rate performances are obtained through simulation. Considering the power allocation issue between the data and training symbols, a sub‐optimal average training power that maximises the lower bound on the effective signal‐to‐interference ratio is also proposed. Simulation results show that the bit error rate performance of the ST is indistinguishable from the OVSF/random ST sequence.