Computation over Wide-Band MAC: Improved Achievable Rate through Sub-Function Allocation

TL;DR

This paper introduces a wide-band CoMAC scheme using OFDM with sub-function allocation and optimized power distribution, significantly enhancing achievable computation rates in large-scale wireless networks.

Contribution

It proposes a novel sub-function allocation method and an adaptive power optimization algorithm for wide-band CoMAC, addressing frequency selectivity challenges.

Findings

Achieves higher computation rates compared to existing methods.

Effectively mitigates rate vanishing as the number of nodes increases.

Validated through theoretical analysis and simulations.

Abstract

Future networks are expected to connect an enormous number of nodes wirelessly using wide-band transmission. This brings great challenges. To avoid collecting a large amount of data from the massive number of nodes, computation over multi-access channel (CoMAC) is proposed to compute a desired function over the air utilizing the signal-superposition property of MAC. Due to frequency selective fading, wide-band CoMAC is more challenging and has never been studied before. In this work, we propose the use of orthogonal frequency division multiplexing (OFDM) in wide-band CoMAC to transmit functions in a similar way to bit sequences through division, allocation and reconstruction of function. An achievable rate without any adaptive resource allocation is derived. To prevent a vanishing computation rate from the increase of the number of nodes, a novel sub-function allocation of sub-carriers is derived. Furthermore, we formulate an optimization problem considering power allocation. A sponge-squeezing algorithm adapted from the classical water-filling algorithm is proposed to solve the optimal power allocation problem. The improved computation rate of the proposed framework and the corresponding allocation has been verified through both theoretical analysis and simulation.