BEM-Based Low-Complexity Analytical Channel Estimation with Optional Iterative Interference Cancellation Over Rapidly Time-Varying Channels for MIMO OFDM Systems
A BEM-based low-complexity channel estimation algorithm with analytical solution is proposed over rapidly time-varying channels for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The time-varying channel taps are estimated with the aid of the designed clustered frequency-multiplexed pilots across different antennas along with basis expansion model (BEM). The proposed approach is specifically designed for MIMO OFDM systems over doubly selective channels. For each subchannel, the derived BEM coefficients can be expressed by explicit analytical solution, whose calculations are partitioned into two steps. During the two steps, two different basis functions such as the critically sampled complex exponential (CCE)-BEM and P-BEM are adopted, respectively. For a MIMO system with \(N_T\) transmit antennas, \(N_R\) receive antennas and \(L\) channel taps, the complexity order of the proposed channel estimation is \(O(N_T N_R L\log L)\), whereas the complexity order of least squares (LS) estimation is \(O((N_T N_R L)^3)\). Additionally, the proposed channel estimation can be iteratively improved in conjunction with hybrid interference cancelation, with only requiring one iteration. Simulation results corroborate the performance advantages of the proposed solution over CCE-BEM based LS scheme under different normalized Doppler spreads.
rapidly time-varying channels mimo ofdm systems low-complexity channel estimation basis expansion model