Maximum likelihood multipath channel estimation for synchronous-CDM systems

In the growing market of digital broadcasting, code division multiplexing (CDM) techniques seem to be very promising. Personal and mobile digital communications applications will have to cope with harsh propagation conditions, characterised by multipath and fading phenomena. Spread spectrum techniques possess intrinsic protection against such frequency-selective channels, but, when the system is loaded, additional multipath processing is required at the receiver side to guarantee good performance. An accurate knowledge of the channel parameters is needed to perform multipath processing. In the paper a novel family of maximum likelihood channel estimators for S-CDM systems is derived. Estimators performance, evaluated and optimised for the Gold code family, shows a good robustness also for large carrier frequency offsets