长期演进系统架构下VoLTE调度机制和传输性能研究

发布时间：2018-06-11 15:14

本文选题：VoLTE + 半持续调度　；参考：《东华大学》2017年硕士论文

【摘要】：LTE(Long Term Evolution)是全IP(Internet Protocol)的分组交换网络,以往2G、3G等电路域交换网络上的语音通话技术在LTE上已经不能够适用,因此需要一种新的全分组域的语音通话解决方案。在经过一系列的技术对比及标准遴选之后,3GPP将基于IMS(IP Multimedia Subsystem)的Vo LTE(Voice over LTE)定为LTE网络中语音的实现技术。本文首先介绍了LTE现有技术并总结了Vo LTE研究现状,然后分阶段介绍了LTE语音业务的演进,对比分析了其各种可能的解决方案,说明了Vo LTE是LTE语音业务最终解决方案的原因。其次,因LTE空中接口协议栈其他各层都已经较为成熟,将研究重点确定在MAC(Media Access Control)层。之后,阐述了MAC层相关信道及其功能,无线调度及其单位,进而针对MAC层中各种调度算法进行了比较,说明最适合Vo LTE的是半持续调度算法。但该算法本身没有针对通话设定优先级,从调度角度来说不够合理,需要进一步进行优化。同时,大部分文献关注了Vo LTE的用户容量、覆盖范围、会话建立及连续性等方面性能,对其无线传输性能却少有研究,本文对这一方面进行了研究。本文主要创新工作如下:1、调度机制方面,本文提出一种改进的基于Vo IP通话优先级的用户结对半持续调度算法,主要分为两个方面的改进:(1)改进Vo IP通话的优先级的计算方式,提出根据通话的队列长度、信号干扰噪声比(Signal to Interference plus Noise Ratio,SINR)、物理资源块需求数、平均信道质量、平均传输速率进行计算,以期更加准确地针对通话进行调度,减少对于控制信令的消耗;(2)改进半持续调度算法的整体流程,提出根据语音分组的丢包率变化动态控制Vo IP优先模式的持续时间,以避免造成其他业务出现饥饿情况;在Vo IP优先模式下,将用户两两结对使其共享分配到的无线资源,减少信道质量差的用户一直重传所导致的无线资源浪费。之后,将该改进应用于Vo LTE调度,以达到进一步降低无线资源调度信令开销,提高对无线资源的利用率及调度效率,提高用户满意度和小区中Vo LTE用户容量的目的。然后,使用MATLAB仿真工具验证了该改进算法对Vo LTE语音分组丢包率、用户满意度和用户容量等方面性能的提升。2、传输性能方面,本文将吞吐量和误码率BER(Bit Error Rate)作为其传输的两个性能指标,主要研究了小区中接收天线的信噪比SNR(Signal to Noise Ratio)对Vo LTE语音帧传输性能的影响,并通过仿真加以分析验证。仿真结果表明在一定的范围之内提高接收天线的信噪比,可以大幅提高Vo LTE的吞吐量,而在范围之外提高信噪比则对于吞吐量的影响不大。提高接收天线的信噪比可以降低传输的误码率。通过将两种天线模型的仿真结果进行对比可知,随着发送与接收天线个数的增多,Vo LTE的传输性能得到增强,同时多天线在一定程度上可以弥补较低信噪比造成的影响。
[Abstract]:Long term Evolution (LTEL) is a packet switching network with full IP IP Internet Protocol. In the past, the voice call technology in 2GN 3G and other circuit-domain switching networks could not be applied to LTE, so a new voice call solution in full packet domain is needed. After a series of technical comparison and standard selection, Vo LTE Voice over LTE, based on IMS IP Multimedia Subsystem, has been selected as the implementation technology of voice in LTE network. This paper first introduces the existing technologies of LTE and summarizes the research status of Vo LTE, then introduces the evolution of LTE voice services in stages, compares and analyzes its various possible solutions, and explains why Vo LTE is the ultimate solution for LTE voice services. Secondly, because the other layers of the LTE air interface protocol stack are mature, the emphasis of the research is on the MAC Media Access Control layer. After that, the correlation channel and its function, wireless scheduling and its units in MAC layer are described. The comparison of various scheduling algorithms in MAC layer shows that the semi-persistent scheduling algorithm is the most suitable for Vo LTE. However, the algorithm itself does not set priority for calls, which is not reasonable from the point of view of scheduling, and needs further optimization. At the same time, most of the literatures focus on the performance of Vo LTE in terms of user capacity, coverage, session establishment and continuity, but little research has been done on its wireless transmission performance. The main innovation work of this paper is as follows: 1, scheduling mechanism. This paper proposes an improved semi-persistent scheduling algorithm based on VoIP call priority, which is divided into two aspects: 1) improve the priority of VoIP calls. According to the queue length, signal to interference plus noise ratio, physical resource block demand, average channel quality and average transmission rate, this paper proposes to calculate the ratio of signal to interference plus noise in order to schedule calls more accurately. To reduce the consumption of control signaling and improve the whole flow of semi-continuous scheduling algorithm, a dynamic control of the duration of Vo IP priority mode is proposed according to the packet loss rate of voice packet, so as to avoid the hunger of other services. In the vo IP priority mode, the wireless resources allocated by pairwise users are shared, which reduces the waste of wireless resources caused by the retransmission of users with poor channel quality. Then, the improved method is applied to Vo LTE scheduling to further reduce the signaling overhead of wireless resource scheduling, to improve the utilization and scheduling efficiency of wireless resources, and to improve user satisfaction and Vo LTE user capacity in the cell. Then, MATLAB simulation tool is used to verify the performance of the improved algorithm to Vo LTE voice packet loss rate, user satisfaction and user capacity. In this paper, throughput and bit error rate (BER-BIT error rate) are taken as two performance indexes. The influence of SNR signal to noise ratio (SNR) of receiving antenna on the performance of Vo LTE speech frame transmission is studied and verified by simulation. The simulation results show that the throughput of Vo LTE can be greatly improved by increasing the SNR of the receiving antenna within a certain range, but the increase of SNR outside the range has little effect on the throughput. The bit error rate of transmission can be reduced by increasing the SNR of the receiving antenna. By comparing the simulation results of the two antenna models, it can be seen that the transmission performance of Vo LTE is enhanced with the increase of the number of transmitting and receiving antennas, and the multi-antenna can compensate for the effect of low SNR to some extent.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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