A correlating receiver for ES-OFDM using multiple antennas

Abstract

Extended Symbol OFDM (ES-OFDM) is applied in case of a multiple antenna receiver. The receiver architecture is based on the observation that OFDM constellation points can be determined by means of correlation. Summing correlations between multiple antennas leads to an interferometer receiver. This approach gives the freedom to choose which correlations are summed. Three antenna structures are explored: a Uniform Linear Array (ULA) and a sparse array where all correlations are summed and a sparse array where only a selection of correlations are summed. The sensitivity of the Bit Error Rate (BER) of an ES-OFDM communication link to an interfering source from different directions is studied. The ULA leads to a relatively wide BER main lobe, the range of angles around the Direction of Arrival of the ES-OFDM signal where the BER is high. Outside this range, the interfering source is suppressed to low BERs, in many cases beyond requirements. By using sparse arrays, the width of the BER main lobe can be traded against the BER levels outside the BER main lobe. This effect is shown for a sparse array where all possible correlations are summed. By summing only those correlations that lead to a uniform co-array, BER levels outside the BER main lobe are lower for an interferometer receiver compared to a traditional beamforming receiver.