移动通信网络VoLTE技术的发展现状及优势

我国的移动通信网络技术历经多年的技术更新和演变,已发展成以VoLTE技术为代表的第四代移动通信技术.目前,VoLTE技术已日益受到重视和广泛应用.VoLTE技术的语音业务优势是4G移动通信时代的最大亮点,它具有比电路域回落方案(CSFB)和终端双待方案更明显的优势.在应用中,VoLTE技术经过了热点覆盖发展期、LTE网络连续覆盖发展期和LTE网络全覆盖发展期三个阶段.VoLTE技术在用户体验、语音接续力、应用范围与业务特性、频谱利用率与覆盖率以及应用成本等方面具有更大的网络优势.     

通信

TN91 2005020754 数据业务自相似特性研究/宋美娜,段云峰,宋俊德,王进(习晾邮电大 学)11通信学报一2004,25(8)一150一155 合适的业务源模型能够在建立理论分析模型或进行系统性能仿真时,使 网络系统性能评价更加准确.自相似特性是数据业务的重要特征.该文 分析了自相似业务源的建模现状,深入讨论了如何将自相似模型应用于 G PRS业务源建模.通过时间序列自相似特性分析工具SELFis,对 中国移动G PRS网络中从一个网关支持节点GGSN处采集的在单位 时间内收到的字节数进行分析,得出G PRS数据业务具有较强自相似 性的结论.图5表1参19(李)…     

语音门户业务及其相关技术介绍

在移动通信从GSM向2.5代和第三代过渡的过程中,电信运营商为其商业利益和技术发展的连贯性,推出了许多增值业务,语音门户就是其中的一种.本文介绍了这项新兴的增值业务,并对其相关技术进行了介绍.     

数据业务自相似特性研究

合适的业务源模型能够在建立理论分析模型或进行系统性能仿真时,使网络系统性能评价更加准确。自相似特性是数据业务的重要特征。本文分析了自相似业务源的建模现状,深入讨论了如何将自相似模型应用于GPRS业务源建模。通过时间序列自相似特性分析工具SELFIS,对中国移动GPRS网络中从一个网关支持节点GGSN处采集的在单位时间内收到的字节数进行分析,得出GPRS数据业务具有较强自相似性的结论。     

基于QoS的3G网络系统设计与研究

为了有效地解决无线通信网络在宽带业务不断增加时产生的拥塞问题,提出了将区分服务模型应用于第三代移动通信网络以满足不同业务对QoS的需求。详细分析了区分服务模型的关键技术以及区分服务模型的系统结构,将区分服务模型和第三代移动通信分组域核心网系统结合起来,设计了支持QoS的第三代移动分组域核心网络。实验表明提出的模型较好地解决了第三代移动网络分组域核心网的QoS问题,提高了对不同业务的服务质量。     

自相似模型下的交换式网络仿真

传统模式下的网络仿真,报文到达均服从的是一种具有短相关特性的泊松分布。而经过大量业务流量监测表明,网络流量实际呈现出的确是一种具有长相关特性的自相似分布,这种特性对网络流量建模、性能分析、接纳控制等产生了重要影响。在对自相似特性深入分析的基础上,利用分型布朗运动模型的RMD算法产生自相似序列来模拟网络业务,并对该业务流特性下的交换式以太网进行了仿真实验。结果表明业务量的自相似性对交换式网络的各项性能影响很大,这与传统流量模型形成鲜明对比。     

自适应独立性假设的非自回归Transformer语音识别

基于非自回归Transformer的端到端自动语音识别模型与自回归Transformer等传统模型相比拥有更快的解码速度,然而非自回归的解码方式与独立性假设导致了语音识别结果准确性的下降.为了解决此问题,提出了一种语音表征融合的自适应独立性假设非自回归Transformer端到端中文语音识别模型.在训练期间,通过对表征向量进行注意力融合,改善decoder输入帧语义信息部分缺失的问题;在解码期间,采用基于自适应独立性假设的解码策略,解决非自回归模型独立性假设带来的输出字符条件独立问题.最后,利用迭代式波束搜索进行多目标的排序搜索解码,解决波束搜索算法在提出模型上的不适用问题.在中文数据集AISHELL-1的实验结果显示,模型的实时性因子达到0.005,字错误率为8.8%,较非自回归Transformer基线模型降低了20%,在保证较高的识别速度的同时大幅降低了错误率,展现出先进的模型性能.     

网络业务流的自相似性

对通信网络的大量研究表明,网络业务本质是自相似的(相关函数上表现为长相关特性)。网络业务的统计自相似性主要是指在不同时间尺度上观测到的业务流量序列具有相同的统计特性。讨论了当前网络业务流的特性;分析了现有的自相似业务流模型。为在线测量网络中的高速业务流,根据实测时间序列数据建立合适模型提供了参考。     

向第三代移动通信过渡方案的选择

向第三代移动通信过渡方案的选择高通公司第三代移动通信系统（３Ｇ）的提出是为了解决第一和第二代系统中的种种不足,使多种无线运行环境统一,提供全球无缝覆盖和漫游,支持多种语音和非话业务,特别是互联网业务和多媒体业务。３Ｇ具有足够的系统容量、强大的多种用户...     

汉语连续语音识别中多项式拟合语音轨迹模型的研究

尽管作为当前最为流行的语音识别模型, HMM由于采用状态输出独立同分布假设,忽略了对语音轨迹动态特性的描述.本文基于一个更为灵活的语音描述统计框架—广义DDBHMM,提出了一个具体的多项式拟合语音轨迹模型,以及新的训练和识别算法,更好地刻划了真实的语音特性.本文还给出了一种有效的剪枝算法,得到一个实用化模型.汉语大词汇量非特定人连续语音识别的实验表明,这种剪枝的多项式拟合语音轨迹模型以较少的计算量明显改善了识别系统的性能.     

蜂窝网络数据业务模型的建立方法

马尔科夫随机过程是电路域业务模型的建立基础。本文首先阐述马尔科夫随机过程理论建立电路域模型业务模型的原理和方法,并指出该方法并不适用于基于信道共享的移动数据业务场景。然后,阐述了移动蜂窝网络的数据业务特征,并重新提出了一种新的数据业务模型,该模型结合了通信网络的实际性能和用户量,可以获得网络最佳在线用户数和最佳吞吐量,从而为移动数据业务的规划和优化奠定可靠的基础。     

Analysis of Bandwidth Gain Over Various Timer$_$CU of AAL2 for Voice Traffic Multiplexing

An asynchronous transfer mode adaptation layer type 2 (AAL2) transmission scheme commonly is used to deliver the voice and tha data traffic between Node-B and the radio network controller on the universal mobile terrestrial device network. To predict the AAL2 multiplexing performance, we analyzed the bandwidth gain and the cell-packing density using discrete Markov chain model for the voice service and validated these results with simulations. We also performed a detailed simulation for the voice and the data services in a concentrator. Based on the analysis, we proposed an engineering guideline for selecting the optimal Timer$_$CU in a Node-B. We found that there is no major benefit in using the AAL2 multiplexing in a concentrator. The benefit of the AAL2 multiplexing in$ I_ ub$for the data service was much less than that for the voice service. They also depended heavily on the traffic load.     

Design and performance evaluation of an RRA scheme for voice‐data channel access in outdoor microcellular environments

In PCS networks, the multiple access problem is characterized by spatially dispersed mobile source terminals sharing a radio channel connected to a fixed base station. In this paper, we design and evaluate a reservation random access (RRA) scheme that multiplexes voice traffic at the talkspurt level to efficiently integrate voice and data traffic in outdoor microcellular environments. The scheme involves partitioning the time frame into two request intervals (voice and data) and an information interval. Thus, any potential performance degradation caused by voice and data terminals competing for channel access is eliminated. We consider three random access algorithms for the transmission of voice request packets and one for the transmission of data request packets. We formulate an approximate Markov model and present analytical results for the steady state voice packet dropping probability, mean voice access delay and voice throughput. Simulations are used to investigate the steady state voice packet dropping distribution per talkspurt, and to illustrate preliminary voice-data integration considerations. This revised version was published online in June 2006 with corrections to the Cover Date.     

A demand assignment system for mobile users in a community ofinterest

The paper presents a high performance wireless access and switching system for interconnecting mobile users in a community of interest. Radio channel and time slot assignments are made on user demand, while the switch operations are controlled by a scheduling algorithm designed to maximize utilization of system resources and optimize performance. User requests and assignments are carried over a low-capacity control channel, while user information is transmitted over the traffic channels. The proposed system resolves both the multiple access and the switching problems and allows a direct connection between the mobile end users. The system also provides integration of voice and data traffic in both the access link and the switching equipment. The “movable boundary” approach is used to achieve dynamic sharing of the channel capacity between the voice calls and the data packets. Performance analysis based on a discrete time Markov model, carried out for the case of optimum scheduling yields call blocking probabilities and data packet delays. Performance results indicate that data packets may be routed via the exchange node with limited delays, even with heavy load of voice calls. Also the authors have proposed scheduling algorithms that may be used in implementing this system     

Performance analysis for voice/data integration on a finite-buffermobile system

Personal communication service (PCS) networks offer mobile users diverse telecommunication applications, such as voice, data, and image, with different bandwidth and quality-of-service (QoS) requirements. This paper proposes an analytical model to investigate the performance of an integrated voice/data mobile network with finite data buffer in terms of voice-call blocking probability, data loss probability, and mean data delay. The model is based on the movable-boundary scheme that dynamically adjusts the number of channels for voice and data traffic. With the movable-boundary scheme, the bandwidth can be utilized efficiently while satisfying the QoS requirements for voice and data traffic. Using our model, the impact of hot-spot traffic in the heterogeneous PCS networks, in which the parameters (e.g., number of channels, voice, and data arrival rates) of cells can be varied, can be effectively analyzed. In addition, an iterative algorithm based on our model is proposed to determine the handoff traffic, which computes the system performance in polynomial-bounded time. The analytical model is validated by simulation     

基于自相似流量预测的拥塞预警方法

摆脱了传统的排队论分析方法,针对高负载情况下的局域网性能评测,提出了一种基于自相似流量预测的拥塞预警方法,对网络流量自相似性的分析和应用,作了有益的探索。     

Performance of Voice/Data Integration on a TDM System

Data queueing is of primary concern in a voice/data integrated TDM system. The data queueing model is represented in the discrete-time domain with multiple servers and voice is given a higher priority than data. The data arrival process is assumed to be Poisson and the voice arrival process is characterized by a Markov chain. The correlation coefficient of the number of on voice calls between consecutive frames is used to measure the correlation behavior of the voice process. While the generating function approach may be used to analyze the queueing process, it involves the evaluation of a large number of boundary terms. On the assumption that the voice traffic consists ofNi.i.d. two-state Markov chains, we derive a simple expression for the mean queue size as a function of two variables in the form of the traffic departure processes. The results clearly reveal a significant influence of the correlation coefficient on the data queueing process. Then, an approximate analysis based on the departure processes is introduced. The numerical and simulation results indicate that this approximate approach yields reasonably accurate results.     

Slot allocation for an integrated voice/data TDMA mobile radiosystem with a finite population of buffered users

Slot allocation for voice and data in an integrated TDMA mobile radio system is investigated. In the proposed system, voice traffic is circuit-switched and data traffic is packet-switched using slotted ALOHA for channel access; the data traffic model is practically assumed to have a finite number of users with finite buffer capacity. The authors apply an equilibrium point analysis (EPA) technique to analyze the data performance and present a heuristic performance criterion to obtain an optimal slot allocation for voice and data in the integrated TDMA mobile radio system     

Analysis of public safety traffic on trunked land mobile radio systems

Mobile radio systems for public safety and agencies engaged in emergency response and disaster recovery operations must support multicast voice traffic. In this paper, we analyze the distribution of call interarrival and call holding times for multicast voice (talk group) traffic on a transmission trunked mobile radio system. In such systems, the channel is held only while a user is making a call (while the push-to-talk key is pressed and the radio is transmitting). We find that the call interarrival time distributions are exponential and exhibit tendency toward long-range dependence. The call holding times best fit lognormal distributions and are not correlated. A potentially important implication of these findings is that performance estimation methods that assume memoryless Markov arrival and departure processes may not be viable approaches.     

Delay Behavior of Data Traffic in an Integrated Voice/Data Multiplex Structure: Multi-Capacity-Limits (MCL) Property

The objective of this paper is to provide insight into the basic behavior of an integrated voice/data multiplex structure by using a two-dimensional Markov analysis. The model for analysis is restricted to the movable boundary case, where the unused capacity for voice traffic is dynamically reassigned to data traffic. Numerical analysis shows a quasicapacity-limit characteristic for the data delay performance. This paper denotes this characteristic as the multi-capacity-limits (MCL) property and investigates it from a number of viewpoints.