面向5G URLLC业务的无线超低时延技术方案探讨

文章基于5G网络中URLLC业务所具备的低时延高可靠特性以及所带来的新的挑战,对空口时延的概念以及URLLC标准进展展开分析,并从减少传输时延间隔、优化资源调度方案等方面对5G无线超低时延技术方案和技术部署展开分析探讨,结果表明,为有效解决时延问题,3GPPR15标准中已经从优化资源调度和缩短传输时间间隔等方面提出可行思路,可为5G网络部署初期低时延业务提供技术支持。     

端边协同保障时延确定性技术研究

工业自动控制等5G垂直行业对网络传输时延与可靠性有着苛刻的要求。聚焦自动导引车（automated guided vehicle,AGV）协同搬运业务场景,深入分析AGV业务关键质量指标（key quality indicator,KQI）与网络时延可靠性需求。现有的5G低时延技术,比如预调度机制通过大量预留空口时频资源降低传输调度等待时延,降低了频谱效率。此外,无线信道弱覆盖、干扰等质差因素会引发较大的时延抖动,难以满足业务时延可靠性需求。针对现有5G网络面临的挑战,设计了一种端边协同时延确定性保障技术方案,基于业务特征进行网络资源预留,同时感知空口信道状态,开启质差保障机制,提升传输可靠性。测试结果表明,端边协同技术方案可以有效提升时延可靠性,降低大时延抖动与优化业务KQI。     

uRLLC业务时延分析及低时延网络部署探讨

uRLLC技术因低时延、高可靠的特性,广泛应用于工业控制、自动驾驶、车联网等场景。为了降低空口时延,3GPP在R15及R16标准中,从优化调度和减少时间间隔等方面提出了一系列的增强技术。这些低时延技术可以不同程度地降低5G网络的空口时延,但是都无法克服TDD制式的等待时延,相对应的FDD制式在低时延方面具有天然的优势。在实际网络中,除了空口时延,影响用户端到端时延的因素还有传输时延及业务平台时延等方面,因此,打造低时延网络是一个系统性工程。     

面向电网业务质量保障的5G高可靠低时延通信资源调度方法

该文研究面向电网业务质量保障的5G 高可靠低时延通信(URLLC)的资源调度机制,以高效利用低频段蜂窝通信系统内有限的频谱和功率资源来兼顾电力终端传输速率和调度时延、调度公平性,保障不同电力业务的通信质量（QoS）。首先,基于URLLC的高可靠低时延传输特性,建立电力终端多小区下行传输模型。然后,提出面向系统下行吞吐量最大化的资源分配问题模型并对其进行分步求解,分别提出基于定价机制与非合作博弈的功率分配算法和基于调度时延要求的改进比例公平算法（DPF）动态调度信道资源。仿真结果表明,提出的资源调度方法能在保证一定传输可靠性和公平性的条件下降低电力终端调度时延,满足不同业务等级的QoS需求,与已知算法对比有一定的优越性。     

本地低时延SDH传输系统优化与设计

运营商迎来了基于S D H承载的专线类业务对低时延的新需求,着眼于本地传输网L2及以下的优化传输策略,在量化分析各组网模式时延指标的基础上,对接入层级、复用过程、传输路由三个方面的时延损耗进行理论分析和研究,并结合实际测试案例,提出本地传输网低时延组网模型及资源调度建议.     

URLLC低时延的技术研究及业务应用

分析了URLLC技术指标要求和工业互联网应用的要求,介绍了4G用户面时延情况和减少4G时延的技术演进,研究和分析了5G实现URLLC低时延的灵活的帧结构、动态HARQ、MEC,mini slot、自包含帧、免授权调度等技术,实现了URLLC低时延在工业控制和远程手术的业务应用。     

5G低时延业务在智能电网的组网应用研究

智能电网是5G低时延业务的重要应用场景.本文结合江西省03专项的实际案例,从5G低时延业务需求、组网方案、业务应用测试等方面,较全面研究了5G低时延电力专网组网与应用,并探索进行了低时延满足度预算分析,比较准确可靠进行网络时延估计,可为工程实践提供参考.     

5G专线业务低时延特性的研究与实现

5G业务场景uRLLC要求端到端时延小于1ms，低时延是5G专线业务最大的特征。网络架构重构为CU-DU-AAU， CU放置位置会影响时延。通过软管道隔离来实现网络切片会造成带宽抢占，丢包重传会增大时延。通过网络结构调整可以降低线路传输时延，通过FlexE的1.5层快速转发可以降低设备转发时延，通过信道硬隔离隔离可以避免业务拥塞。综合以上技术方案可以有效实现5G专线业务低时延的特性。     

网络时延对数据中心布局的影响研究

随着5G、移动互联网、大数据、人工智能等信息技术与经济社会各领域的深度融合,不同业务数据对传输时延提出了不同要求,低时延业务需求迅速增长,网络时延已成为用户选取数据中心的重要指标。在端到端分析数据包传输的基础上,重点研究了影响网络时延的主要因素及相应的优化措施,并提出数据中心选址的建议。     

基于微时隙的eMBB和uRLLC业务传输性能研究

超可靠低时延通信(Ultra Reliable Low Latency Communications, uRLLC)是5G移动通信技术的重要场景之一。相较于增强移动宽带(Enhanced Mobile Broadband, eMBB),uRLLC业务有严格的时延、可靠性要求，对数据速率的要求相对较低。在5G NR中，uRLLC业务可以使用微时隙结构抢占eMBB资源进行传输，保证uRLLC业务满足时延要求，同时实现与eMBB业务的复用。基于微时隙结构进行业务抢占的方法，研究了在微时隙结构部署uRLLC业务时，eMBB业务和uRLLC业务的传输性能。首先为eMBB业务用户配置传输资源，然后使用微时隙结构将uRLLC业务穿刺到正在运行的eMBB业务中，在uRLLC业务传输完成后的下一个时隙开展eMBB业务重传以保证uRLLC业务的低时延要求。为了进一步降低uRLLC业务的块误码率，在使用微时隙穿刺的同时，通过设置更大的子载波间隔抑制载波间干扰。通过理论分析评估了该场景中eMBB业务和uRLLC业务的块误码率(Block Error Rate, BLER)和吞吐量性能；在时延性能方面，在对用户...     

Latency of the pupillary response

The authors give an explanation of pupillary latency in terms of nonminimum phase lag. Minimum phase lag is that phase associated with a simple linear lag element; nonminimum phase is associated with a true delay element modeled as exp (-ST). Latency can be accurately modeled by a delay element. The authors experimentally demonstrate that pupillary latency increases with reductions in intensity and increases with frequency of the square-wave stimuli. They summarize these characteristics with a model     

HSPA网络业务建立时延研究

以厦门HSPA网络为对象,利用多种数据源重点分析了业务建立过程中RRC和RAB建立阶段的时延,定位了影响时延的终端类型、业务类型、组网策略、信令流程设置等因素,并结合DT测试数据评估了现网业务建立总时延及端到端建立时延.     

无线传感器网络S-MAC协议的时延控制

S—MAC协议是基于竞争的传感器网络MAC层协议，通过使节点空闲时自动转换为休眠状态来节省能耗。然而，休眠模式的引入导致了数据前传中断问题，使时延显著增加。时延问题使得S—MAC协议不能理想地应用于实时数据采集系统中。在S—MAC中引入了快速数据前传算法（FDF），仿真表明，采用FDF算法的S—MAC协议比采用自适应侦听算法的S—MAC协议显著减少了时延（对于10跳的网络，端到端的时延减少了将近一倍），因而显著地增加了网络的吞吐量。     

LTE系统时延分析

介绍由eNodeB构成的单层结构的LTE系统对时延的要求,从用户面时延、控制面时延进行具体的理论分析,并通过举例进一步介绍LTE系统在inter—eNB切换中的业务中断时延。     

On-Chip Power-Grid Simulation Using Latency Insertion Method

Ensuring the integrity of the power supply in the power distribution networks (PDNs) of a chip is essential for building reliable high-performance chips. To ensure the power integrity, accurate, and memory- and time-efficient simulation approaches for simulating the power-supply noise in the on-chip PDN are essential. In this paper, a finite-difference formulation based on the latency insertion method (LIM) has been employed for simulating the power-supply noise in the on-chip PDN. A new common-mode type equivalent circuit has been proposed. In this equivalent circuit, a capacitance to ideal ground may not be present at all the nodes. Further, the nodes can be capacitively coupled to each other. To avoid inverting a large nonbanded matrix, a small capacitance to ground is added to a node that did not have any capacitance to ground, and a small series inductance is added to any floating capacitor that did not have any series inductance. Approximate closed-form expressions to compute the values of these capacitances to ground and series inductances have been proposed. The accuracy of the LIM-enabled transient simulation and the accuracy of the proposed closed-form expressions have been demonstrated. The memory and time complexity of the simulation for each time step have been shown to be O(N_n) each, where N_n is the number of nodes in the equivalent circuit. Stability condition is derived for the first time for multidimensional inhomogeneous RLC circuit. A upper bound of the time step is derived from the stability condition. Using this bound on the time step, the runtime of the overall transient simulation has been estimated to be approximately proportional to N_n ^2-2.5 for N_n in the order of millions.     

Latency analysis of the Totem single-ring protocol

The Totem single-ring protocol provides reliable totally ordered multicasting of messages to processes in process groups over a single local-area network (LAN) using a logical token-passing ring. The protocol provides two levels of message delivery: delivery in agreed order and delivery in safe order. This paper presents the probability density functions (PDFs) for the latency to message delivery for the Totem single-ring protocol for these two levels of service in the presence of both message loss and token loss. These PDFs are calculated by repeated convolutions of the PDFs for the various components of the latency. The analysis shows that the mean latency to safe delivery is greater than the mean latency to agreed delivery and that the tail of the latency distribution for safe delivery is longer. It also shows that a deterministic arrival process for message generation exhibits lower mean latencies and shorter tails of the latency distribution than a Poisson arrival process     

一种低延迟的可扩展调度算法

提出了一种基于阈值的分布式迭代算法。与现有算法不同的是,该算法针对可扩展网络交换调度结构的特点,为处于最高优先级的调度器安排了2次迭代,第1次迭代用阈值方法找出一些较长的VOQ（虚拟输出队列）,并在最高优先级时隙之前的一个时隙完成,以缩短信号的处理时间。仿真结果表明,该算法与现有算法相比,在大流量的uniform流量模式下,延时性能和吞吐率获得了明显的提高。同时,该算法的硬件代价小,有效地实现了性能和复杂度的良好折中。     

一种CORBA中间件通信时延性能优化方法

CORBA是一种广泛应用于软件无线电系统的中间件.为了满足软件无线电系统高实时性要求,本文提出基于oneway关键字的中间件通信时延性能优化方法.利用该方法,通信时延降低近60％.     

面向5G标准的低延时LDPC编码器设计

针对 5G 标准中对低延时和编码灵活性的要求, 本文提出了一种高并行度的低密度奇偶校验(Low-Density Parity-Check, LDPC)码编码算法并设计了相应的硬件结构。 编码算法对校验位的计算流程进行了改进, 通过将对应 5G 标准中校验矩阵单对角和双对角结构的不同编码步骤并行化提高了运算速度。 在硬件结构上一方面设计了多路并行的运算结构通过同时求解多个编码步骤降低了处理时延, 另一方面灵活的结构设计使其可以有效地支持5G不同场景下对码长和码率的要求, 并通过分组计算校验位实现了对递增冗余的HARQ (IR-HARQ)方案的支持。仿真结果表明,在 200 MHZ 的系统时钟频率下, 本设计的信息吞吐量可达 35Gbps。      

A New Low Latency Parallel FIR Filter Scheme

A new array type parallel scheme for an FIR digital filter is presented in this paper. The proposed scheme is based on the structure of the carry-save array multiplier where each cell implements the computation of an FIR filter at the bit-level. This structure leads to latency independent of the number of the filter taps. The proposed scheme is pipelined at the bit-level, is systolic at the cell-level and requires less hardware than other schemes based on discrete multipliers.Paraskevas Kalivas received his Diploma and Ph.D. degree in electrical and computer engineering from the National Technical University of Athens, Greece, in 1990 and 2000 respectively.His research interests include computer arithmetic and efficient realization of arithmetic circuits and digital filters.Vassilis Vassilakis received his Diploma in electrical and computer engineering from NationalTechnical University of Athens, Greece, in 1997. He isworking toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include efficient circuit implemenation of DSP algorithms and java processor architectures.Chris Meletis received his Diploma in electrical and computer engineering from National Technical University of Athens in 1997. Currently, he is working toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include multirate filter banks, digital filter design and their efficient realization.Kiamal Z. Pekmestzi received his Diploma in electrical engineering from the National Technical University of Athens, Greece, in 1975. From 1975 to 1981, he was a research fellow in the Electronics Department of the Nuclear Research Center Demokritos. He received his Ph.D. in electrical engineering from the University of Patras, Greece, in 1981.From 1983 to 1985, he was a professor at the Higher School of Electronics in Athens. Since 1985, he has been with the National Technical University of Athens, where he is currently a professor. His research interests include computer arithmetic, VLSI digital filters and VLSI design automation.