Superimposed or time-division multiplexed pilots in time-varying channels: an informative consideration

Two major techniques are used to embed pilots into data, time-division multiplexed ( TDM ) and superimposed ( SIP ). In this paper, we compare these two techniques in an informative consideration under time varying fading channels. Besides the ordinary SIP without dealing with the interference, we also study two different kinds of performance improved iterative SIP : interference subtraction ( IS ) and interference exploitation ( IE ). Using Wiener filtering and accounting estimation error, the capacity lower bounds and BER expressions are derived. Numerical results show that great potential benefits are brought by SIP if the interference is utilized properly. With this potential exploited, SIP shows great superior to PSAM , especially in high speed environments.