Pilot Placement for Time-Varying MIMO OFDM Channels With Virtual Subcarriers
The rapid time-variation of a fading multipath environment can impair the performance of Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO OFDM). This paper proposes a pilot placement method for MIMO OFDM systems under time-varying channels with the guard band. The time-varying channel is described by complex exponential Basis Expansion Model (BEM). The authors discuss the Least Square (LS) channel estimation to obtain the Minimum mean Square Error (MSE) and derive the pilot allocation that can satisfy the minimum MSE with regard to guard band in time-varying channels.