一种新的CDMA软切换算法及其对软切换性能的改善

定义了残余容损比(RCLR)的概念,提出了一种新的基于最大RCLR的无线移动CDMA小区系统的软切换判决算法,称之为RCLR算法。区别通常的最小路径损耗(MPOL)算法,RCLR算法不仅考虑了呼叫业务的路径损耗,而且兼顾了小区负载平衡。最后,通过分别在单层小区系统和分层小区系统中进行仿真,比较了RCLR算法和MPOL算法的软切换性能,仿真结果表明RCLR算法显著地改善了呼叫业务的中断概率和分层小区系统的层间溢出概率,减少了软切换次数。     

分层小区系统中预留资源的切换策略分析

分层小区结构是增强覆盖,提高系统容量,为具有不同移动特性的用户提供更好服务质量的一种有效的解决方案.本文讨论了具有分层小区结构的CDMA(码分多址)系统中切换策略的性能,分别用一维和二维的马尔可夫模型来分析微蜂窝和宏蜂窝中的状态.CDMA的自干扰特性使得其系统容量与干扰水平相关,因此我们采用状态空间无限的马尔可夫模型来进行分析.另外,考虑到切换用户的优先级问题,以及具有不同移动特性的用户的公平性问题,我们在系统中设置了多级接入门限,同时分析了资源预留量对系统性能的影响.     

一种新的CDMA分层小区系统中的层间切换方案

介绍了用于分层小区系统层间切换的压缩模式,提出了一种新的触发压缩模式的标准,即分组周期触发压缩模式。仿真结果说明,无论小区内的用户数怎样变化,分组周期压缩模式的切换阻塞率都比周期压缩模式的切换阻塞率低。     

分层小区系统自适应控制择层策略

本文提出了一种分层小区系统自适应控制择层策略,一个自适应门限和两个辅助门限被利用进行层选。同时,利用各小区逗留时间之间的相关性对呼叫业务在将要进入的小区内的归一化逗留时间进行预测估计,提供了一种估计移动台在小区中的逗留时间的新思路。最后通过仿真验证了该策略的性能,得出了具体结论。     

移动通信系统中的切换和切换算法

切换是蜂窝系统所独有的功能，也是移动通信系统的一个关键特征，它直接影响整个系统的性能。本对移动通信系统中切换和切换算法进行了深入细致的研究，包括切换的分类和功能、性能指标、各种切换方式及算法的优缺点，提出了自己的建议及需要继续研究的问题。     

VOLTE异系统切换占比高小区分析

本报告统计了高频次小区数,分布情况。文章根据异系统e SRVCC切换占比高情况结合实际提出处理方法。     

WCDMA与GSM系统间切换浅析

本文介绍了WCDMA系统和GSM系统间切换和小区重选的操作过程,分析了压缩模式对网络质量的影响,并对提高切换成功率提出了几点建议.另外,本文对切换相关的GSM网络升级和测量控制参数的设置也进行了讨论.     

基于TD-LTE无线网络切换性能优化分析

TD-LTE是当前移动通讯开发、研究的一门网络新技术,是一种OFDM(正交频分复用)技术,能供应较大的数据业务,因此,其实用性备受人民关注.本文是基于测试数据对网络实际业务应用的分析,包括吞吐量和规模试验,另外从实际应用数据的几个方面如:站点位置、发射功率等角度进行分析,优化出适合实际使用的方法,促进了TD-LTE网络的实际应用的发展.     

一类离散切换系统的性能分析

针对一类含有不确定性和时滞的离散切换系统,探讨了H∞性能分析问题。假设所考虑的线性不确定性具有线性分式形式,综合利用Lyapunov-Krasovskii函数和Finsler’s引理,给出判断系统满足H∞性能界γ的充分条件,并且γ的上界可以通过求解一组线性矩阵不等式获得。最后通过一个数值算例说明方法的有效性。     

移动通信系统中的切换和切换算法

切换是蜂窝系统所独有的功能,也是移动通信系统的一个关键特征,它直接影响整个系统的性能。本文对移动通信系统中切换和切换算法进行了深入细致的研究,包括切换的分类和功能、性能指标、各种切换方式及算法的优缺点,提出了自己的建议及需要继续研究的问题。     

Performance modeling of multitier PCS system

The emergence of multitier wireless access is being driven by the different compromises in technology required to provide wireless service in different environments. Three major tiers of wireless access are likely to emerge to providepersonal communications services (PCS): high-tier, low-tier, and unlicensed. Because of the service costs of the three tiers, the unlicensed system is given the highest priority to deliver the calls, and the high-tier system has the lowest priority to deliver the calls. To maintain this delivery priority, two multitier mobility management strategies have been proposed: the single registration strategy (SR) and the modified multiregistration strategy (MR). This paper proposes a new strategy called the lazy deregistration strategy (LDR) and compares the performance of the three strategies. We show that in most cases, LDR outperforms both SR and MR. The registration cost of SR is always no less than the cost of MR. The advantage of MR over SR is more significant if (i) when the user moves into the low-tier system, it is more likely that the currently visited low-tier VLR (visitor location register) is the same as the previously visited VLR, and (ii) the mobile station (MS) is more likely to move between the low-tier system and the high-tier system. The call delivery cost of MR is always no less than the cost of SR. The advantage of SR over MR is more significant if (i) the call arrival rate is large, (ii) the cost of delivering a call to the low-tier system is large, and (iii) the MS is likely to stay in the high-tier system.     

一种改进的基于HLR/VLR体系结构的终身号码方案

在PCS系统中，终身号码允许用户在改变运营商时保留其原有电话号码，本文提出的基于HLR/VLR体系结构Cache改进算法，能保证用户在多次改变运营商时，使用户实现真正的号码携带。在当前无线网络运营中，基于HLR/NLR体系结构位置管理的无线网络取得了极大成功，使得研究基于HLR/NLR体系结构的终身号码方案具有非常重要的现实意义。与原基于HLR／VLR位置管理Cache算法相比，本文算法的实现只需要软件升级和存储器扩容。随着软硬件技术的发展，使本文提出的方案具有较强的可行性。     

Performance analysis of flexible hierarchical cellular systems witha bandwidth-efficient handoff scheme

In this paper, a bandwidth-efficient handoff strategy is proposed and analyzed for hierarchical cellular systems. Mobile subscribers are divided into two classes, i.e., low- and high-mobility subscribers. In our bandwidth-efficient handoff strategy, each of the originating and handoff calls of both slow and fast mobile subscribers first tries to get a channel in a microcell. Macrocells are overlaid over the microcells to handle overflowed calls. A call overflowed into a macrocell requests a take-back to the new microcell at each border crossing of the microcells. The request will be accommodated by the target microcell if there is any idle traffic channel in the cell. An analytical model is developed, and the most important performance measures such as the blocking probability of originating calls and the forced termination probability of calls are evaluated. It is shown through extensive comparisons with other candidate handoff strategies that if the total traffic load of the system is not very heavy, our scheme has the best bandwidth efficiency and can provide better quality of service for mobile subscribers without bringing too much processing expense to the system     

Performance evaluation of hierarchical cellular CDMA networks with soft handoff queueing

We consider hierarchical cellular code-division multiple-access networks supporting soft handoff, where users with different mobility are assigned to different layers, i.e., microcells in the lower layer are used to carry slow users, whereas macrocells in the upper layer are for fast users, and handoff queues are provided for handoff calls that cannot obtain the required channel immediately, so that forced termination probability can be reduced. According to whether handoff queues are provided in microcells and/or macrocells, four different call admission control schemes are proposed and studied. We derive the mathematical model of the considered system with multidimensional birth-death process and utilize Gauss-Seidel iterative method to find the steady-state probability distribution and thus the performance measures of interest: new call blocking probability, handoff failure probability, and forced termination probability. Analytical results show that providing handoff queues in both microcells and macrocells can achieve largest performance improvement. Furthermore, handoff queue size greater than a threshold is shown to have little effect on performance measures of interest. Last but not least, the studied two-tier system is compared with a one-tier counterpart. It is shown that the two-tier system performs better in terms of average number of handoffs per fast call.     

Teletraffic modeling and analysis of flexible hierarchical cellularnetworks with speed-sensitive handoff strategy

Hierarchical cellular networks with subscribers of varying mobility are considered. Microcells are used to address the high-intensity traffic of mainly slow mobility areas, and macrocells are overlaid over the microcells to cater mainly to high-mobility lower density traffic. The two tiers of microcells and macrocells provide a secondary resource for new traffic as well as handoffs for mobile subscribers of different mobility classes. Furthermore, resources in alternate layers are monitored to assign the appropriate resource types when they become available. We develop an analytical model to evaluate the performance of such systems, and quantify the gain obtained by providing overflow to alternate resources as well as the advantages in resource reassignment according to the speed classification     

HLR Replication Protocols for Global Mobility Management in PCS Networks

The new trend for PCS networks is to provide mobile users with large-scalemobile capability across many service areas. In this scenario, global databasemanagement for PCS networks has become an increasingly important researchissue.In this paper, we examined two replicated database strategies,single-replica (SR) and multiple-replica (MR), for large-scalemobility of per-user data management in personal communicationnetworks. The SR strategy uses a single replica approach of HLR.The MR strategy replicates the per-user data of HLR in manyregions. The two strategies are based a partial replicationscheme, and a primary copy method is used to maintain replicas'consistency. Our numerical results show that the MR strategyoutperforms the SR strategy in most situations; however, it may beworse when the probability of a mobile user visiting a foreignregion is high and the query rates from other foreign regions arelow. Additionally, the number of replicas should be compact in theMR strategy in order to achieve a reasonable query response time.Therefore, we propose an adaptive multiple replication protocol tochoose a suitable replication strategy and to decide the optimizednumber of replicas.     

PCS网络中位置管理的二级HLR法

本文对PCS系统中漫游用户的位置管理提出了一种新的处理方法：二级HLR法。与IS－41、GSM以及前向指针法相比，它可使系统在用户漫游时节省长登记、注销业务量以及避免长途网络资源分配的浪费，同时又不会对运营商提出过高的基础网络建设要求。通过使漫游用户信息放入漫游地HLR的专用储存区（即漫游用户登记操作本地化）从而尽可能降低其登记注销开销。由于存储器价格日趋下降，本文提出的方案具有较强的可行性。     

Performance analysis of soft handoff in CDMA cellular networks

The code-division multiple-access (CDMA) scheme has been considered as one possible choice of the future standards for cellular networks because of its various advantages. Since there can be only one carrier frequency being used in CDMA systems, a handoff scheme with diversity, a so-called “soft handoff”, was proposed for higher communication quality and capacity. A mathematical model is developed to analyze the soft handoff process. Markov's concept is applied to describe the system's steady state statistical behavior. System performance such as blocking probability, handoff refused probability, and channel efficiency are also determined. It is concluded that the larger the area the soft handoff region is, the better users in the cellular network will feel     

An analytical model of two-tier handoff mechanisms for a hierarchical NEMO system

In this paper, we present an analytical model of two-tier handoff mechanisms for a hierarchical NEMO system composed of access routers (ARs), mobile routers (MRs), and visiting mobile nodes (MNs). In the proposed two-tier handoff mechanism, service areas of MR and AR are respectively divided into handoff and non-handoff regions. Consequently, concurrent voice/data sessions in a hierarchical AR-MR model can be classified into four types according to the locations of MN and MR within the MR's and the AR's service areas, respectively. We build a mathematical model with 4-D Markov chains to analyze the performance in terms of the system utilization and the blocking probabilities of new sessions and handoff sessions. For the purpose of validation, we conduct experiments through simulation. Simulation results reveal that both the blocking probabilities of new sessions and handoff sessions are very close to the analytical results, particularly when the system utilization is high. The impacts of session residence time and session arrival rates on the blocking probabilities are also investigated.     

Performance analysis of soft handoff in CDMA cellular networks

A unique feature of code division multiple access (CDMA) systems is the use of soft handoff between cells. Soft handoff, in general, increases the system capacity because while the link between a mobile and one base station is poor, it might be better between the same mobile and some other base station. Hence, the user may transmit at a lower power in a soft handoff situation. Teletraffic analysis of soft handoff is complex because one cannot separate transmission issues from traffic issues. Many papers in the literature have independently analyzed the effect of soft capacity and soft handoff on network performance. Some papers have analyzed the effect of soft handoff on soft capacity but there has been no proper teletraffic analysis that includes both soft capacity and soft handoff. This paper proposes a traffic model for a DS-CDMA cellular network that includes both soft capacity and soft handoff. Network performance is then computed in terms of call blocking