Block-IFDMA — Iterative Channel Estimation Versus Estimation with Interpolation Filters

Abstract

In this paper, Discrete Fourier Transform (DFT) precoded Orthogonal Frequency Division Multiple Access (OFDM) with block-interleaved subcarrier allocation per user is considered which is denoted as Block Interleaved Frequency Division Multiple Access (B-IFDMA). The B-IFDMA parameter design is affected on the one hand by considerations to reduce the energy consumption by entering a micro sleep mode. These considerations recommend a transmission on a high number of subcarriers and a small number of successive symbols. On the other hand, in terms of channel estimation, an increasing number of successive symbols is beneficial to reduce the pilot symbol overhead. The paper contributes to the choice of the B-IFDMA system parameters, i.e., blocksize in frequency domain and number of successive symbols in time domain, that are investigated in consideration of channel estimation performance and pilot symbol overhead. Further on, a novel iterative Decision Directed Channel Estimation with Wiener filtering is proposed that requires only one pilot carrying B-IFDMA symbol in time domain and, thus, reduces the pilot symbol overhead especially if a small number of successive symbols is transmitted. In this paper, this novel channel estimation algorithm is introduced and compared to Wiener interpolation filtering and additionally to a low-complexity channel estimation approach.