Ultra-Power-Efficient DigiLogue Processing for Ultra-Wide Bandwidth Wireless Systems

Abstract

Exploiting ultra-wide bandwidths is a promising approach to achieve the terabits per second (Tbps) data rates required to unlock emerging mobile applications like mobile extended reality and holographic telepresence. However, conventional digital systems are unable to exploit such bandwidths efficiently. In particular, the power consumption of ultra-fast, high-precision digital-to-analogue and analogue-to-digital converters (DACs/ADCs) for ultra-wide bandwidths becomes impractical. At the same time, achieving ultra-fast digital signal processing becomes extremely challenging in terms of power consumption and processing latency due to the complexity of state-of-the-art processing algorithms (e.g., “soft” detection and decoding) and the fact that the increased sampling rates challenge the speed capabilities of modern digital processors. To overcome these challenges, we herein propose a shift towards the DigiLogue processing, according to which, computationally intensive and power-hungry digital signal processing tasks take place directly in the analogue domain, avoiding DACs/ADCs, but still preserving the performance of conventional digital transceiver algorithms. However, existing analogue-based approaches have inferior spectrum utilization than digital approaches, partly due to their inability to exploit the recent advances in digital systems such as “soft” detection and decoding. In this context, we propose a simple-to-implement “soft” information calculation for the generalized M-ary modulations in the analogue domain suitable for DigiLogue receivers that can also be used by any analogue “soft” channel decoders (e.g., with low-density parity-check code (LDPC)). In addition, in the pursuit of developing more practical DigiLogue receivers, we propose a technique for estimating fading channel parameters in the analogue domain. Subsequently, we leverage this acquired information to design a channel equalization and “soft” detection approach tailored for fading channels, specifically suited for DigiLogue receivers. We show that the proposed DigiLogue receivers have negligible (i.e., less than 0.1 dB) signal-to-noise ratio (SNR) degradation in terms of error performance compared to digital systems while achieving more than an order of magnitude power gains depending on the modulation order.