Design of Two-Step Random Access Procedure for URLLC Applications

Area of Science:

• Telecommunications Engineering
• Wireless Communication Systems
• Network Performance Optimization

Background:

• Fifth-generation (5G) ultra-reliable low-latency communication (URLLC) requires control plane (C-plane) latency below 10ms, a significant reduction from fourth-generation (4G) LTE-A's average 80ms.
• High C-plane latency in 4G systems is primarily due to the contention-based random access procedure (RAP).

Purpose of the Study:

• To propose and evaluate a simplified 2-step random access procedure (RAP) for 5G URLLC.
• To significantly reduce C-plane latency to meet stringent 5G URLLC requirements.

Main Methods:

• Simplified the conventional 4-step contention-based RAP to a 2-step procedure.
• Utilized demodulation reference signals for User Equipment (UE) identification.
• Implemented reserved preambles specifically for URLLC users.

Main Results:

• The proposed 2-step RAP demonstrated significant improvements in success rates compared to the 4-step RAP.
• Success rates for the 2-step RAP were 83.81% higher when fixing the number of URLLC users.
• Success rates were 71.83% higher when fixing the number of reserved preambles for URLLC users.

Conclusions:

• The optimized 2-step RAP effectively reduces C-plane latency.
• The proposed method successfully achieves the 10ms latency requirement for 5G URLLC applications.
• This simplification offers a viable solution for enhancing URLLC performance.