Quasi-Dynamic Frame Coordination for Ultra-Reliability and Low-Latency in 5G TDD Systems

Abstract

The fifth generation (5G) mobile technology features the ultra-reliable and low-latency communications (URLLC) as a major service class. URLLC applications demand a tight radio latency with extreme link reliability. In 5G dynamic time division duplexing (TDD) systems, URLLC requirements become further challenging to achieve due to the severe and fastvarying cross link interference (CLI) and the switching time of the radio frame configurations (RFCs). In this work, we propose a quasi-dynamic inter-cell frame coordination algorithm using hybrid frame design and a cyclic-offset-based RFC code-book. The proposed solution adaptively updates the RFCs in time such that both the average CLI and the user-centric radio latency are minimized. Compared to state-of-the-art dynamic TDD studies, the proposed scheme shows a significant improvement in the URLLC outage latency, i.e., ∼ 92% reduction gain, while boosting the cell-edge capacity by ∼ 189% and with a greatly reduced coordination overhead space, limited to B-bit.

On the Ultra-Reliable and Low-Latency Communications in Flexible TDD/FDD 5G Networks

“…We evaluate the URLLC radio performance using inclusive system level simulations [7], where the major functionalities of the physical and media access control layers, respectively, are implemented according to the latest 5G-NR specifications. The default simulation assumptions are listed in Table I, unless otherwise mentioned.…”

“…e.g., the related head of line delay). Although, when different neighboring BSs concurrently adopt opposite transmission link directions, it comes with the cost of potentially severe cross-link interference (CLI) [7]. CLI is highly critical for achieving the URLLC outage requirements, where especially the BS-BS CLI is problematic due to the higher BS transmit power as compared to the UE transmit powers.…”

“…In [8], coordinated inter-cell user scheduling, and advanced UL power control are introduced to minimize the average network CLI. Furthermore, opportunistic frame coordination schemes [7,9] are proposed to pre-avoid the occurrence of the BS-BS and UE-UE CLI on a besteffort basis. Moreover, perfect BS-BS CLI cancellation using full packet exchange and orthogonal projector estimation are discussed in [10,11].…”

Online Radio Pattern Optimization Based on Dual Reinforcement-Learning Approach for 5G URLLC Networks

“…The drawback of those proposals is mainly the requirement of a large inter-cell signaling overhead space. Therefore, simpler and less-coordinationoverhead demanding opportunistic CLI avoidance schemes [16,17] have been suggested to offer attractive capacity and latency merits, where the BS-BS and UE-UE CLI is preaverted on a best effort basis. This encompasses the design of a hybrid TDD pattern with a slot-aware dynamic UE scheduling.…”

“…• Unlike the state-of-the-art relevant TDD solutions [7][8][9][10][11][12][13][14][15][16][17][18][19], the proposed solution considers the joint capacity and latency statistics to optimize the URLLC outage latency performance. It is fully compliant with the current 3GPP 5G-NR standard specifications for dynamic-TDD deployments.…”