URLLC use cases demand a new paradigm in cellular networks to contend with the extreme requirements with complex trade-offs. In general, it is exceptionally challenging and, resource usage-wise, prohibitively expensive to satisfy the URLLC requirements using the existing approaches in LTE. To address these challenges 3GPP has recently agreed to adopt PD of both UP and CP packets as a fundamental technique in 5G NR. This article investigates the theoretic framework behind PD and provides a primer on the recent enhancements applied in the NR RAN architecture for supporting URLLC. It is shown that PD enables jointly satisfying the latency and reliability requirements without increasing the complexity in the RAN. With dynamic control capability, PD can be used not only for URLLC but also to increase the transmission robustness during mobility and against radio link failures. The article also provides numerical results comparing the performance of PD in various deployment scenarios. The numerical results reveal that in certain scenarios, performing PD over multiple links results in lower usage of radio resources than using a single highly reliable link. It is also found that to improve radio resource utilization while satisfying URLLC requirements, enabling PD in scenarios such as cell edge is crucial where the average SNR of the best (primary) link and the variation in SNR between all accessible links is typically low. In essence, the PD technique provides a cost-effective solution for satisfying the URLLC requirements without requiring major modifications to the RAN deployments.

中文翻译：

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5G中URLLC的数据包复制：体系结构增强和性能分析

URLLC用例需要蜂窝网络中的新范例，以应对具有复杂权衡的极端要求。通常，使用LTE中的现有方法来满足URLLC要求极具挑战性，并且在资源使用方面非常昂贵。为了应对这些挑战，3GPP最近同意在5G NR中采用UP和CP数据包的PD作为基本技术。本文研究了PD背后的理论框架，并为NR RAN体系结构中为支持URLLC所应用的最新增强功能提供了入门知识。结果表明，PD可以共同满足延迟和可靠性要求，而不会增加RAN的复杂性。具有动态控制功能 PD不仅可以用于URLLC，而且可以提高移动性和防止无线电链路故障时的传输鲁棒性。本文还提供了数值结果，用于比较各种部署方案中PD的性能。数值结果表明，在某些情况下，与使用单个高度可靠的链路相比，在多个链路上执行PD会导致无线资源的使用率降低。还发现，为了在满足URLLC要求的同时提高无线电资源利用率，在诸如最佳小区（主要）链路的平均SNR和所有可访问链路之间的SNR变化通常较低的小区边缘等场景中启用PD至关重要。本质上，PD技术提供了一种经济有效的解决方案，可以满足URLLC要求，而无需对RAN部署进行重大修改。