Direct Data Detection of OFDM Signals over Wireless Channels

This paper presents a novel efficient receiver design for wireless communication systems that incorporate orthogonal frequency division multiplexing (OFDM) transmission. The proposed receiver does not require channel estimation or equalization to perform coherent data detection. Instead, channel estimation, equalization, and data detection are combined into a single operation, and hence, the detector performs a direct data detector ($D^{3}$). The $D^{3}$ is applied to key practical wireless systems such as the Long Term Evolution (LTE) and the New Radio (NR) of the fifth-generation (5G) system. The performance of the proposed $D^{3}$ is thoroughly analyzed theoretically in terms of bit error rate (BER), where closed-form accurate approximations are derived for several cases of interest, and validated by Monte Carlo simulations. Moreover, extensive complexity analysis are performed to evaluate the system suitability for implementation. The obtained theoretical and simulation results demonstrate that the BER of the proposed $D^{3}$ is only 3 dB away from coherent detectors with perfect knowledge of the channel state information (CSI) in flat and frequency-selective fading channels for a wide range of signal-to-noise ratios (SNRs). If CSI is not known perfectly, then $D^{3}$ outperforms the coherent detector substantially, particularly at high SNRs with linear interpolation. The computational complexity of $D^{3}$ depends on the length of the sequence to be detected, nevertheless, a significant complexity reduction can be achieved using the Viterbi algorithm.