MC-WiFi: A Low-Latency and Ultra-Reliable PHY Layer Architecture for Mission-Critical Machine-Type Communications

Mission-critical Machine-Type Communication (mcMTC), also termed Ultra-Reliable Low- Latency Communication (URLLC), demands ultra-high reliability and very low latency for concurrent short-packet transmissions in industrial automation, power systems, healthcare, and safety-critical applications. However, current wireless standards for mcMTC rely on general-purpose PHY layers with only upper-layer customisation, leaving the physical layer (PHY) design insufficiently optimised for the stringent requirements of missioncritical services. This research proposes an innovative PHY layer architecture — Mission Critical WiFi (MC-WiFi)—built upon the IEEE 802.11a standard. The architecture targets a substantial reduction in PHY layer packet transmission time and a significant improvement in transmission reliability through three primary contributions: (1) a single-symbol preamble design reducing overhead from 16 μs to 4 μs; (2) a novel Packet Detection and Channel Synchronisation (PDCS) algorithm operating on one preamble symbol; and (3) block-wise polar codes with CRC-aided Successive Cancellation List (CRC-SCL) decoding for short-packet error correction. Mathematical analysis and simulation results demonstrate that MC-WiFi achieves a PHY layer packet transmission time of 5 μs (at 80 MHz) and reliability of Packet Error Rate (PER) ≤ 10^-7 as confirmed by the finiteblocklength normal approximation bound, with direct Monte Carlo simulation (10^6 iterations) validating PER ≤ 10^-5 — outperforming all reviewed industry standards and prior proposals.