# Magneto-inductive Passive Relaying in Arbitrarily Arranged Networks

## TL;DR

This paper analyzes magneto-inductive passive relaying in arbitrarily arranged wireless sensor networks, revealing multipath-like channel behavior and proposing strategies to enhance channel power gain for improved network performance.

## Contribution

It provides the first analysis of passive relaying in arbitrary network topologies and introduces methods to improve relay utilization and channel gain.

## Key findings

- Channel exhibits multipath-like fading characteristics.
- Deactivation and frequency tuning improve relay network performance.
- Passive relays can significantly enhance communication range.

## Abstract

We consider a wireless sensor network that uses inductive near-field coupling for wireless powering or communication, or for both. The severely limited range of an inductively coupled source-destination pair can be improved using resonant relay devices, which are purely passive in nature. Utilization of such magneto-inductive relays has only been studied for regular network topologies, allowing simplified assumptions on the mutual antenna couplings. In this work we present an analysis of magneto-inductive passive relaying in arbitrarily arranged networks. We find that the resulting channel has characteristics similar to multipath fading: the channel power gain is governed by a non-coherent sum of phasors, resulting in increased frequency selectivity. We propose and study two strategies to increase the channel power gain of random relay networks: i) deactivation of individual relays by open-circuit switching and ii) frequency tuning. The presented results show that both methods improve the utilization of available passive relays, leading to reliable and significant performance gains.