On the Fast DHT Precoding of OFDM Signals over Frequency-Selective Fading Channels for Wireless Applications

Due to high power consumption and other problems, it is unlikely that orthogonal frequency-division multiplexing (OFDM) would be included in the uplink of the future 6G standard. High power consumption in OFDM systems is motivated by the high peak-to-average power ratio (PAPR) introduced by the inverse Fourier transform (IFFT) processing kernel in the time domain. Linear precoding of the symbols in the frequency domain using discrete Hartley transform (DHT) could be used to minimise the PAPR problem, however, at the cost of increased complexity and power consumption. In this study, we minimise the computation complexity of the DHT precoding on OFDM transceiver schemes and the consequent power consumption. We exploit the involutory properties of the processing kernels to process the DHT and IFFT as a single-processing block, thus reducing the system complexity and power consumption. These also enable a novel power-saving receiver design. We compare the results to three other precoding schemes and the standard OFDM scheme as the baseline; while improving the power consumption efficiency of a Class-A power amplifier from 4.16% to 16.56%, the bit error ratio is also enhanced by up to 5 dB when using a 1/2−rate error-correction coding and 7 dB with interleaving

Impulse noise mitigation using precoded SCFDMA for uplink PLC systems

This article presents a new transceiver structure for uplink power line communication (PLC) system based on single carrier frequency division multiple access (SCFDMA) for the mitigation of inherent PLC noise i.e. impulse noise. Moreover, SCFDMA also promises low PAPR values than the conventional orthogonal frequency division multiple access (OFDMA). Furthermore, this work also suggests the employment of linear precoding via Walsh Hadamard transform (WHT) and Zadoff Chu transform (ZCT) to improve the transceiver performance. Adaptive bit loading is also recommended instead of fixed loading to circumvent the channel impairments. Performance of the proposed transceiver in terms of bit error rate (BER) and peak to average power ratio (PAPR) is evaluated in the form of simulations. Results demonstrate that the proposed transceiver for uplink PLC systems perform better than the conventional transceiver design in the presence of additive white Gaussian noise (AWGN) and impulse noise