A NEW CALL CONTROL SCHEME OF PUSH-TO-TALK SYSTEM

For Push-To-Talk (PTT) system based on Public Mobile Data Network (PMDN), the end-to-end time delay is the key aspect of the user's experience. The Push-Over-Cellular (POC) scheme defined by Open Mobile Alliance (OMA) is based on the VoIP phone model and use SIP protocol as the call control scheme. The call setup time delay in SIP may reach to several seconds, which is unac-ceptable for the PTT service. In this paper, we provide a new call control scheme for PTT system based on PLMN network. By combining the apriority knowledge of PTT call model and the priority control scheme, we encapsulate the signaling message and the voice data into a same data packet, when the user push the button, the voice and the call control signaling are sent to the server at the same time. So the long time delay of call setup procedure of POC scheme can be eliminate. The end-to-end call delay can be decreased significantly. The experiment result based on the commercial CDMA2000 1X network of China Unicom shows that the call delay can be decreased to 600 ms, which approach to the traditional trunk communication system's requirement.

New degradation call admission control for increasing WCDMA system capacity

Propose a new degradation call admission control（DCAC）scheme, which can be used in wideband code division multiple access communication system. So-called degradation is that non-real time call has the characteristic of variable bit rate, so decreasing its bit rate can reduce the load of the system, consequently the system can admit new call which should be blocked when the system is close to full load, therefore new call＇s access probability increases. This paper brings forward design project and does system simulation, simulation proves that DCAC can effectively decrease calls＇ blocking probability and increase the total number of the on-line users.

A Combining Call Admission Control and Power Control Scheme for D2D Communications Underlaying Cellular Networks

As device-to-device(D2D) communications usually reuses the resource of cellular networks, call admission control(CAC) and power control are crucial problems. However in most power control schemes, total data rates or throughput are regarded as optimization criterion. In this paper, a combining call admission control(CAC) and power control scheme under guaranteeing QoS of every user equipment(UE) is proposed. First, a simple CAC scheme is introduced. Then based on the CAC scheme, a combining call admission control and power control scheme is proposed. Next, the performance of the proposed scheme is evaluated. Finally, maximum DUE pair number and average transmitting power is calculated. Simulation results show that D2 D communications with the proposed combining call admission control and power control scheme can effectively improve the maximum DUE pair number under the premise of meeting necessary QoS.

Adaptive Terminal-Modality-Based Joint Call Admission Control for Heterogeneous Cellular Networks

The coexistence of different Radio Access Technologies (RATs) requires a need for Common Radio Resource Management (CRRM) to support the provision of Quality of Service (QoS) and the efficient utilization of radio resources. The provision of QoS is an important and challenging issue in the design of integrated services packet networks. Call admission control (CAC) is an integral part of the problem. Clearly, without CAC, providing QoS guarantees will be impossible. There is unfairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous wireless networks. In this paper, an Adaptive-Terminal Modality-Based Joint Call Admission Control (ATJCAC) algorithm is proposed to enhance connection-level QoS and reduce call blocking/dropping probability. The proposed ATJCAC algorithm makes call admission decisions based on mobile terminal modality (capability), network load, adaptive the bandwidth of ongoing call and radio access technology (RAT) terminal support index. Simulation results show that the proposed ATJCAC scheme reduces call blocking/dropping probability.

Terminal-Modality-Based Joint Call Admission Control Algorithm for Fair Radio Resource Allocation in Heterogeneous Cellular Networks

There is a problem of unfairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous wireless networks. Low-capability mobile terminals (such as single-mode terminals) suffer high call blocking probability whereas high-capability mobile terminals (such as quad-mode terminals) experience very low call blocking probability, in the same heterogeneous wireless network. This paper proposes a Terminal-Modality-Based Joint Call Admission Control (TJCAC) algorithm to reduce this problem of unfairness. The proposed TJCAC algorithm makes call admission decisions based on mobile terminal modality (capability), network load, and radio access technology (RAT) terminal support index. The objectives of the proposed TJCAC algorithm are to reduce call blocking/dropping probability, and ensure fairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous networks. An analytical model is developed to evaluate the performance of the proposed TJCAC scheme in terms of call blocking/dropping probability in a heterogeneous wireless network. The performance of the proposed TJCAC algorithm is compared with that of other JCAC algorithms. Results show that the proposed algorithm reduces call blocking/dropping probability in the networks, and ensure fairness in allocation of radio resources among heterogeneous terminals.

Unified Performance and Availability Model for Call Admission Control in Heterogeneous Wireless Networks

The system capacity of wireless networks varies temporally. This may be due to the dynamic allocation of the channels and also the mobility of the users. The change in capacity will create greater impact on the system performance parameters. This variation of capacity particularly poses a greater challenge to the research community to ensure the Quality of Service (QoS) as it affects the call blocking probability which is one of the important QoS parameters. This paper proposes a performance model for call admission control and the availability model for a heterogeneous wireless network environment. The proposed model is able to handle three types of traffic considered for the study includes conversation traffic, interactive traffic and background traffic. The unified performance-availability model is developed using the Stochastic Area Networks (SAN). The performance of both analytical models and the SAN based performance-capacity models are verified by taking the call blocking probabilities for all the three types of traffics.

Analysis of Different Call Admission Control Strategies and Its Impact on the Performance of LTE-Advanced Networks

The call admission control (CAC) optimizes the use of allocated channels against offered traffic maintaining the required quality of service (QoS). Provisioning QoS to user at cell-edge is a challenge where there is limitation in cell resources due to inter-cell interference (ICI). Soft Frequency Reuse is ICI mitigation scheme that controls the distribution of resources between users. In this paper, the Impact of four CAC schemes (Cutoff Priority scheme (CP), Uniform Fractional Guard Channel (UFGC), Limited Fractional Guard Channel (LFGC), New Call Bounding (NCB) scheme) at cell-edge have investigated using queuing analysis in a comparative manner. The comparison is based on two criteria. The first criterion guarantees a particular level of service to already admitted users while trying to optimize the revenue obtained. The second criterion determines the minimum of number of radio resources that provides hard constraints in both of blocking and dropping probabilities. The four schemes are compared at different scenarios of new and handover call arrival rates.

Downlink call admission control with power allocation and rate scheduling for IDMA-based multi-beam satellite systems

Considering the advantage of interleave-division multiple-access(IDMA) technique and the technical bottlenecks in the existing satellite systems,IDMA is introduced into satellite communication networks.To further validate the IDMA into satellite systems,an effective call admission control(CAC) is proposed to maximize the resource utilization.After establishing the multi-beam satellite system model based on variable spreading gain(VSG) IDMA,the power allocation scheme based on SINR evolution technique and transmission rate adaptation for nonreal time interactive traffic are designed as integrated parts of the CAC,working together to improve the system performance in terms of power efficiency and throughput.Further,the analysis and simulation results show that IDMA under the proposed scheme can provide better QoS,in terms of the blocking/dropping probability,outage probability as well as delay performance.

Call Admission Control in HAP W-CDMA Cellular Systems

Among various radio sources which control different dependencies/functions, in this article, we will talk about the Call Admission Control (CAC), and we are supposed to confine our concentration on W-CDMA which is based on high raised platforms, since during the recent years remarkable amount of attention has been focused on platforms located in stratosphere layer [1]. Firstly, we study the capacity of uplink from HAP (High Altitude Platform) W-CDMA and we’ll work on estimation and power control defects in a new conversation added to current conversations. We’ll enhance the Call Admission Control (CAC) based on the side effects of power control defects and users’ stimulus and then compare the CAC which has been measured by using of momentary energy on bit in the spectral density form (Eb/N0). Then we examine the mentioned charts for two different criteria which the decision will be made by these criteria in order to decide if exchanged calls are to be admitted or not. The first criterion is based on the minimum of (Eb/N0) of the first row cells meanwhile the second criterion is based on the average of (Eb/N0) of first row-cells.

Performance Analysis of Multi-Parametric Call Admission Control Strategies in Un-Buffered Multi-Service Cellular Wireless Networks

In this paper model of integrated voice/data cellular wireless networks (CWN) are investigated. The unified approximate approach to calculate the desired Quality of Service (QoS) metrics in an isolated cell of such networks under two multi-parametric call admission control (CAC) strategies is developed. One of them is based on the guard channels scheme while the second is based on a threshold scheme. Results of the numerical experiments are given and a comparison of QoS metrics under different CAC strategies is carried out.

基于局部路径图的自动化漏洞成因分析方法

快速的漏洞成因分析是漏洞修复中的关键一环,也一直是学术界和工业界关注的热点.现有基于大量测试样本执行记录进行统计特征分析的漏洞成因分析方法,存在随机性噪声、重要逻辑关联指令缺失等问题,其中根据测试集测量,现有统计方法中的随机性噪声占比达到了61%以上.针对上述问题,提出一种基于局部路径图的漏洞成因分析方法,其从执行路径中,提取函数间调用图和函数内控制流转移图等漏洞关联信息.并以此为基础筛除漏洞成因无关指令(即噪声指令),构建成因点逻辑关系并补充缺失的重要指令,实现一个面向二进制软件的自动化漏洞成因分析系统LGBRoot.系统在20个公开的CVE内存破坏漏洞数据集上进行验证.单个样本成因分析平均耗时12.4 s,实验数据表明,系统可以自动剔除56.2%噪声指令和补充并联结20个可视化漏洞成因相关点指令间的逻辑结构,加快分析人员的漏洞分析速度.

空中交通管制中相似航班号解决策略探究

在繁忙时段或繁忙扇区,同一管制员可能会连续指挥多架具有相似航班号的航空器,受通信波道质量不佳或语言发音等影响,极易造成陆空通话双方误听、误复诵、误操作,增加了双方的工作负荷,对飞行安全产生较大威胁。本文将结合相似航班号的概念和分类,通过相关案例,分析相似航班号对飞行安全的影响,提出解决相似航班号问题的建议,以便降低运行风险,更好地保障飞行安全。

基于铁路5G-R的自主化机车无线同步操控技术方案

为探讨基于5G-R的自主化机车无线同步操控技术方案,通过调研自主化机车无线同步操控业务需求,分析我国重载铁路既有通信系统的不足,充分考虑5G-R网络的高带宽、低延迟、IP化链路、分组域传输、QoS优先级保障等特性,提出总体技术方案,重点论述主从控机车数据传输、可控列尾数据传输、编组请求、多司机通话等功能的实现方案。该研究结果有利于提升自主化机车无线同步操控系统的先进性,确保其在复杂环境下的可靠运行,对提升重载铁路运输生产安全和效率具有指导意义,为重载铁路的现代化和智能化发展提供强有力的技术支持。

MODELING MULTI-TRAFFIC ADMISSION CONTROL IN OFDMA SYSTEM USING COLORED PETRI NET

Call Admission Control (CAC) is one of the key traffic management mechanisms that must be deployed in order to meet the strict requirements for dependability imposed on the services provided by modern wireless networks. In this paper, we develop an executable top-down hierarchical Colored Petri Net (CPN) model for multi-traffic CAC in Orthogonal Frequency Division Multiple Access (OFDMA) system. By theoretic analysis and CPN simulation, it is demonstrated that the CPN model is isomorphic to Markov Chain (MC) assuming that each data stream follows Poisson distribution and the corresponding arrival time interval is an exponential random variable, and it breaks through MC's explicit limitation, which includes MC's memoryless property and proneness to state space explosion in evaluating CAC process. Moreover, we present four CAC schemes based on CPN model taking into account call-level and packet-level Quality of Service (QoS). The simulation results show that CPN offers significant advantages over MC in modeling CAC strategies and evaluating their performance with less computational complexity in addition to its flexibility and adaptability to different scenarios.

Analysis of Completion of Call with on-off Data Source in Wireless Networks

In wireless network, call completion probability accounts for users' satisfaction since the admitted ongoing call may be interrupted during hand-off process or even stay in the same cell when dynamically allocating resource to calls because of the loss of resource. We focus on the relationship between call's completion probability and these interruptions and develop an analytical relationship model for homogeneous cellular networks based on probability analysis. Then assuming call's data source is modeled by on-off traffic model, a two dimensional Markov process is established to compute these blocking and dropping probabilities for call's completion probability. The impacts of different new call arrival rate, call's traffic characteristic, user's mobility, call's holding time and call's admission threshold on call's completion are evaluated and compared through numerical examples. These results show that call's completion reaches its maximum value if making no difference between hand-off call and new call in the case of light traffic load. But some resource should be reserved for the hand-off call in high traffic scenario. The analytical model provides a basis for helping to set the call admission threshold. Key words on-off traffic source - call completion probability - call admission control - wireless networks CLC number TN 919. 72 Foundation item: Supported by the National Natural Science Foundation of China (60172077)Biography: XUAN Xiao-ying (1972-), female, Ph. D candidate, research direction: radio resource management and scheduling in wireless networks.

医院护理呼叫系统无线寻呼功能研究

医院护理呼叫系统是一种用于护士站内实现护士与病人之间呼叫、对讲的设备装置,它可以使病人及时获得医护人员的帮助。通过调研和查阅资料了解到,大部分医院的护理呼叫系统均为有线呼叫系统。尽管已经出现了基于无线通信技术的护理呼叫系统,但是在这样的呼叫系统中医护人员只有返回护士站,才能通过主机上的按键和电话与患者取得联系。这在很大程度上限制了医护人员的灵活性,也增加了他们的工作量。提出了两种实现无线呼叫的方法,可以实现护士与患者的方便快捷的联系,具有一定的推广使用价值。

基于拥塞理论的广电网络客服呼叫接入控制方法

针对当前方法存在客服呼叫接入队列瞬时长度变化波动较大的问题,提出一种基于拥塞理论的广电网络客服呼叫接入控制方法。通过构建网络拥塞控制模型,将此模型作为后续环节的基础。构建自适应呼叫接入控制器,设定闭环控制模式。利用拥塞理论以及控制器,提出客服呼叫接入控制算法约束条件,实现接入控制过程。实验结果表明方法可降低客服呼叫接入队列瞬时长度变化波动,提高控制过程平稳度,提升广电网络运行稳定性。

基于语音识别的医院病房呼叫系统设计

阐述医院病房呼叫系统的需求分析,对传统的呼叫系统进行优化,提出病床呼叫系统分类呼叫设计方案,按照红、黄、橙、蓝四种颜色,划分病人呼叫的请求等级,从而实现不同等级的请求分类呼叫,护士可以更为高效准确地区分病人请求的紧急程度,从而科学制定同时请求的应对策略,最大限度降低出现忽略紧急情况的可能性。探讨基于语音识别视角的病房分类呼叫系统设计方案,及其应用效果评估。

基于PLC的银行排队叫号系统设计

文章设计了银行排队叫号系统,采用西门子S7-200控制,通过数码管显示和蜂鸣器等人机交互设备实现银行取号自动化服务。排号系统主要由显示部分、取号部分、系统信息处理部分以及后台操作部分组成。通过合理排序程序结构,实现排队系统抽号,提高排队等待效率,防止出现队伍秩序混乱和在等待过程中插队或其他造成流程不规范的情况,以期借助智能数字化叫号系统提高银行业务办理水平。

基于PBX程控电话交换机与运营商IMS电话交换机呼叫转移实现的探究

固定电话呼叫转移是电话交换机的功能之一,为用户通讯提供了便利。在工信部规范运营商数据标准化、规范化的背景下,运营商取消了用户交换机的“透传”功能,导致用户小型电话交换机在实现与运营商呼叫转移时,用户电话显示不正常的情况。在此背景下,基于“爱立信”PBX程控电话交换机,对呼叫转移显示不正常的情况进行了探究,提供了思路和解决办法,为电话交换机传输信令(Q.931补充协议)的完善提供了参考建议。