Latency performance analysis of low layers function split for URLLC applications in 5G networks
Latency performance analysis of low layers function split for URLLC applications in 5G networks
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DOI：
10.1016/j.comnet.2019.106865
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发表时间：
2019-10
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通讯作者：
Yahya M. Alfadhli;You-Wei Chen;Siming Liu;Shuyi Shen;Shuang Yao;D. Guidotti;S. Mitani;G. Chang
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文献类型：
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作者：
Yahya M. Alfadhli;You-Wei Chen;Siming Liu;Shuyi Shen;Shuang Yao;D. Guidotti;S. Mitani;G. Chang
在4G云无线电接入网络(C-RAN)中，移动前端的延迟主要被认为是前端长度的限制因素。只要前端延迟不会导致违反混合自动重复请求(HARQ)限制，前端延迟就不会对端到端延迟产生影响。然而，超可靠低延迟通信(URLLC)的出现预示着需要有效的延迟减少机制，例如小型时隙和基于非时隙的传输，以使URLLC数据能够即时传输。这意味着前端的任何延迟都会影响URLLC应用的端到端往返时间(RTT)延迟，因此应仔细评估。另一方面，在边缘节点整合更多功能，也称为远程单元(RU)，最近已成为减少5G网络延迟的可行解决方案，但牺牲了增加的复杂性和资本/运营成本(CAPEX/OPEX)。在本文中，我们使用商用现成设备(COTS)对URLLC应用的不同低功能拆分选项在前端的实验延迟进行了定量分析。我们还演示了具有最简单的远程单元设计，其中只包含一个模拟光电转换器，用选项-9表示，可以实现最低的前端延迟。基于我们的发现，我们设计了一个灵活的5G架构，可以高效地支持不同的5G应用。
In 4G cloud radio access networks (C-RAN), latency at the mobile fronthaul was conceived mainly as a limiting factor of the fronthaul length. As long as fronthaul latency is not leading to violation of the hybrid automatic repeat request (HARQ) limit, the fronthaul latency would not have impact on the end-to-end latency. However, the advent of ultra-reliable low latency communications (URLLC) portends the need for effective latency reduction mechanisms, such as mini-slot and non-slot-based transmission, to enable URLLC data to be transmitted instantly. This implies that any delay at the fronthaul will impact the end-to-end round trip time (RTT) latency of URLLC applications and therefore should be carefully evaluated. On the other hand, consolidating more functions at the edge node, also known as remote unit (RU), has recently gained traction as a viable solution to reduce latency in 5G networks, with the sacrifice of increased complexity and capital/operational expenses (CAPEX/OPEX). In this paper, we provide experimental quantitative latency analysis of different low function split options at the fronthaul for URLLC applications using commercial off-the-shelf equipment (COTS). We also demonstrate that having the simplest remote unit design, which only contains an analog optical-to-electrical convertor, denoted by Option-9, can achieve the lowest fronthaul latency. Based on our findings, we design a flexible 5G architecture that can efficiently support different 5G applications.