Improving Network Availability of Ultra-Reliable and Low-Latency Communications with Multi-Connectivity

TL;DR

This paper introduces a framework to enhance network availability in URLLC by leveraging multi-connectivity, combining D2D and cellular links, and considers practical factors like shadowing and processing delays.

Contribution

It provides a quantitative definition of network availability in short blocklength regimes and demonstrates how multi-connectivity can significantly extend communication range under URLLC constraints.

Findings

Multi-connectivity improves available communication range.

Considering shadowing and processing delays affects range optimization.

Simulation confirms the effectiveness of multi-connectivity in URLLC.

Abstract

Ultra-reliable and low-latency communications (URLLC) have stringent requirements on quality-of-service and network availability. Due to path loss and shadowing, it is very challenging to guarantee the stringent requirements of URLLC with satisfactory communication range. In this paper, we first provide a quantitative definition of network availability in the short blocklength regime: the probability that the reliability and latency requirements can be satisfied when the blocklength of channel codes is short. Then, we establish a framework to maximize available range, defined as the maximal communication distance subject to the network availability requirement, by exploiting multi-connectivity. The basic idea is using both device-to-device (D2D) and cellular links to transmit each packet. The practical setup with correlated shadowing between D2D and cellular links is considered. Besides, since processing delay for decoding packets cannot be ignored in URLLC, its impacts on the available range are studied. By comparing the available ranges of different transmission modes, we obtained some useful insights on how to choose transmission modes. Simulation and numerical results validate our analysis, and show that multi-connectivity can improve the available ranges of D2D and cellular links remarkably.