Optimizing Packet Reception Rates for Low Duty-Cycle BLE Relay Nodes

TL;DR

This paper presents a BLE relay device design that extends network coverage and improves packet forwarding efficiency in IoT mesh networks, achieving up to 35% forwarding with a year-long battery life.

Contribution

We designed and experimentally evaluated a battery-powered BLE relay to enhance mesh network coverage and efficiency in large indoor IoT environments.

Findings

Up to 35% of packets forwarded by a single relay in optimal scenarios.

Battery life of approximately 1 year at 20% relay duty cycle.

Effective range extension for BLE mesh networks in indoor settings.

Abstract

In order to achieve the full potential of the Internet-of-Things, connectivity between devices should be ubiquitous and efficient. Wireless mesh networks are a critical component to achieve this ubiquitous connectivity for a wide range of services, and are composed of terminal devices (i.e., nodes), such as sensors of various types, and wall powered gateway devices, which provide further internet connectivity (e..g, via WiFi). When considering large indoor areas, such as hospitals or industrial scenarios, the mesh must cover a large area, which introduces concerns regarding range and the number of gateways needed and respective wall cabling infrastructure. Solutions for mesh networks implemented over different wireless protocols exist, like the recent Bluetooth Low Energy (BLE) 5.1. Besides range concerns, choosing which nodes forward data through the mesh has a large impact on performance and power consumption. We address the area coverage issue via a battery powered BLE relay device of our own design, which acts as a range extender by forwarding packets from end nodes to gateways. We present the relay's design and experimentally determine the packet forwarding efficiency for several scenarios and configurations. In the best case, up to 35% of the packets transmitted by 11 nodes can be forwarded to a gateway by a single relay under continuous operation. A battery lifetime of 1 year can be achieved with a relay duty cycle of 20%.