Reception Characteristics of OFDM Signals using Array Antennas

Abstract

Reception characteristics of OFDM signals using array antennas have been analyzed. In OFDM systems, equalizers are used to compensate for the amplitudes and phases of received symbols distorted by multipath propagation. For simplicity, DQPSK modulation, which does not require equalization, is also used. However, in single-antenna systems, degradation of the signal-to-noise ratio of specific carriers due to frequency selective fading can not be compensated for. Array antennas were used to improve the characteristics of carriers whose signal-to-noise ratio was degraded by multipath propagation. To achieve an optimal combination of signals from each antenna, the channel transfer functions were estimated by using scattered pilot symbols. The bit error rate characteristics for DQPSK, PSK and 16QAM were examined using computer simulation and were found to be much better than those of single-antenna receivers.