Contention-Based Access for Ultra-Reliable Low Latency Uplink Transmissions

We consider a sporadic ultra-reliable and low latency communications in the uplink 5G cellular systems. Reliable low latency access for randomly emerging packet transmission cannot be guaranteed in current wireless systems. To achieve the goal of low latency and high reliability simultaneously, we propose a contention-based transmission scheme aimed at users with small payloads. We seek to reduce collision probability by considering multiple transmissions for the same packet for reliable reception. We find the optimal number of consecutive multiple transmissions that reduces collisions and achieves target reliability within the latency window. Performance is analyzed with a frame structure planned for 5G cellular systems. Results are compared with default multi-channel slotted ALOHA access scheme.