Estimation of CSI for LST BS-CDMA systems using special sequences with pre-defined spectral nulls

Layered space-time block spread CDMA (LST BSCDMA) has been previously proposed as an alternative to conventional CDMA systems for high-rate mobile communications. This paper proposes two approaches to obtain channel state information (CSI) for LST BS-CDMA system. The basic approach suffers from high computational complexity and poor performance in systems with high order of transmitter diversity due to inter-layer interference (ILI). The second approach reduces computation complexity and eliminates ILI, making it suitable for systems with higher order of transmitter diversity. The detailed simulation studies show that the highly accurate CSI obtained using the improved technique leads to considerable superior performance.