Analysis of Two-Step Random Access Procedure for Cellular Ultra-Reliable Low Latency Communications

Due to the emergence of Internet Things (IoTs), it can be expected that bandwidth provided by cellular systems might consumed up soon. Some applications them are delay-sensitive such would critical guarantee random access (RA) delay less than a threshold. Since existing Long-Term Evolution-Advanced (LTE-A) RA procedure is four-step signaling procedure, may not suitable for due its time-consuming procedure. This work investigates two-step 5G New Radio systems, where preamble and request message transmitted at same time. First we show operating region divided into three regions as unsaturated stable, bistable, saturated in terms packet generation probability, retransmission number devices, preambles. To see whether requirement guaranteed, this shows system should run under derives distribution when IoT devices employ geometric probability backoff (GPB) or uniform window (UWB) algorithm. We then examine larger some threshold depending on operation regions.