New pilot allocation design schemes for sparse channel estimation in OFDM system

In this paper, the problem of the deterministic pilot allocation for sparse channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) system is investigated. This method is based on mutual coherence minimization of the measurement matrix associated with the OFDM system pilot subcarriers. It is known that if the set of pilot pattern is a Cyclic Difference Set (CDS), the mutual coherence of the measurement matrix is minimized. However, CDS in most practical OFDM system is not available. Few research efforts have tackled the problem of pilot allocation by proposing methods that lead to suboptimal solutions in order to ignore the computationally complex exhaustive search method. This contribution, however, proposes two pilot allocation design schemes for the construction of deterministic partial Fourier matrices satisfying the Restricted Isometry Property (RIP) namely, the Generic Random Search (GRS) and Progressive Search (PS) based on bounding the mutual coherence between different columns of the measurement matrix. Simulation results show that the two proposed pilot allocation design schemes are effective and offer a better channel estimation performance in terms of MSE when compared to former pilot allocation design methods.