Low-latency Symbol-Synchronous Communication for Multi-hop Sensor Networks

TL;DR

This paper introduces a symbol-synchronous transmission scheme for multi-hop wireless sensor networks that leverages concurrent transmissions and symbol-by-symbol relaying to achieve wire-like latency on RF bands such as the 2.4 GHz ISM band. By transmitting and relaying data symbol-by-symbol with a fixed timing structure and a robust detector that uses a detection window, the approach delivers low end-to-end latency that scales sublinearly with hop count and maintains low BER in moderate-range deployments. MATLAB-based simulations show around 5 ms end-to-end latency for a 512-bit packet and BER as low as 0.04% at practical distances, with a data rate of 100 kbps, significantly higher than comparable approaches. The work demonstrates the viability of RF synchronous transmissions for ultra-low-latency IoT and robotics applications, while acknowledging the need for hardware validation and future enhancements such as adaptive power, error correction, and more realistic scenarios.

Abstract

Wireless sensor networks (WSNs) have received great interest due to their scalability, energy efficiency, and low-cost deployment. By utilizing multi-hop communication, WSNs can cover a wide area using low transmission power without the need for any communication infrastructure. Traditionally, WSNs rely on store-and-forward routing protocols and Time Division Multiple Access (TDMA)-based schedules that avoid interference between different wireless nodes. However, emerging challenging scenarios, such as the industrial Internet of Things (IoT) and robotic swarms, impose strict latency and reliability requirements, which traditional approaches cannot fulfill. In this paper, we propose a novel symbol-synchronous transmission design that provides reliable low-latency communication with a reasonable data rate on classical sub-6GHz RF frequency bands (e.g., the 2.4GHz ISM band). Instead of avoiding overlapping transmissions, the proposed scheme benefits from concurrent transmissions. Using simulation in MATLAB, we prove that the proposed design allows achieving a wire-like delay of 5ms for a 512-bit packet over multiple hops with only a 0.3% latency increase per extra hop and a low bit error rate (BER) of 0.04%. Compared to similar state-of-the-art approaches it can achieve a significantly higher data rate of 100kbps, which is expected to increase further with future improvements of the system.

Figures (8)

• Figure 1: Network topology
• Figure 2: Pulse-based OOK modulation scheme
• Figure 3: Symbol-synchronous transmission
• Figure 4: Detection scheme
• Figure 5: Average BER for various grid distances.