Performance analysis of vector OFDM with linear MMSE receiver

Vector OFDM (V-OFDM) for single transmit antenna systems is a general transmission scheme in which OFDM and Single-Carrier Frequency Domain Equalization (SC-FDE) can be considered as two extreme/special cases. Due to its flexibility, it has attracted more and more attention recently. So far all studies about V-OFDM assume the Maximum Likelihood (ML) receiver. In this paper, we investigate the performance of V-OFDM with linear Minimum Mean Square Error (MMSE) receiver. We first show that for linear MMSE receiver, all the vector blocks (VB) in V-OFDM have equal performance, this is different from V-OFDM with ML receiver, where different VBs may have different performances. Then, we analyze the diversity order of V-OFDM with linear MMSE receiver, and show that, regardless of the V-OFDM symbol length N, the diversity order can be represented as min{[M2^_R], D} + 1, where M is the VB size, R is the spectrum efficiency in bits/symbol, and D is the maximum delay of the multipath channel.