CDMA2000-1X系统多业务复合越区切换策略

提出一种多业务综合越区切换策略,该策略同时支持实时业务和非实时业务;通过双队列模式解决了实时业务的虚拟切换问题,有效地利用资源、缓解呼叫和切换拥塞;并通过建立多维马尔科夫链越区切换策略模型,为请求越区切换的实时业务提供了抢占优先和排队相结合的策略。仿真结果表明,系统的呼损率、阻塞率、强制中断概率等系统性能指标得到明显改善。     

一种新的基于多业务的移动通信系统切换策略

针对目前移动通信系统大部分信道切换策略中新呼叫阻塞率高的问题,提出了一种新的呼叫延迟切换策略,该策略是让即将占用最后一个空闲信道的新呼叫短暂延迟后再占用空闲信道,切换呼叫则直接占用空闲信道,缩短了信道被全部占用的时间,增加了新呼叫和切换呼叫占用信道的机会。该策略同时考虑了数据业务之间的优先级,只有当高优先级数据队列中的数据包为空时,低优先级队列中的数据包才能够占用信道。给出了切换呼叫掉话率、新呼叫阻塞率及数据包掉包率的理论公式。与预留信道策略和可移动边界策略的对比表明,新策略既提高了新呼叫进入系统的概率,又有效降低了切换呼叫的掉话率,同时也减少了高优先级数据的掉包率。     

基于多业务的移动通信系统呼叫接入控制

针对在可移动边界保护信道方法中新呼叫堵塞率高的问题,提出一种呼叫接入控制策略。当切换呼叫的掉话率小于门限时,新呼叫以一定的概率使用为切换呼叫预留的保护信道。当高优先级数据等待队列中的数据包为空时,传输普通数据等待队列中的数据包。仿真结果表明,在对切换呼叫掉话率影响较小的前提下,该策略能够有效降低新呼叫的堵塞率和高优先级数据的掉包率。     

无线多媒体网络中一种基于测量网络状态的动态呼叫接纳控制算法

提出了一种无线多媒体网络中基于测量网络状态的动态呼叫接纳控制算法.它区分了实时和非实时业务,在网络带宽资源不足时可通过降低非实时业务带宽确保实时业务呼叫连接的可靠性;还可根据当前网络状况调整预留带宽大小,使小区实时业务切换呼叫掉线率低于设定的门限值.大量仿真结果显示该算法具有低实时业务切换呼叫掉线率和与固定预留方案相当的带宽利用率,而只以略高的新呼叫阻塞率为代价,适合各种不同概率发生时实际应用的情况.     

基于业务类别的联合呼叫接纳控制算法

提出了一种基于业务类别的联合呼叫控制算法。在网络接入选择时,实时业务相对于非实时业务来说,应该尽可能地减少切换次数、降低切换时延。非实时业务要求较高的数据传输速率,而对时延不敏感。因此,在两个网络资源都足够的情况下,实时业务首选接入蜂窝网络,非实时业务首选接入WLAN。仿真并分析了异构网络中呼叫接纳控制算法性能的重要指标:新业务阻塞率。仿真结果表明,所提算法考虑了负载均衡,有效地利用了系统中的资源,提高了系统中的资源利用率,新业务阻塞率明显降低。     

异构分层无线网络中基于业务QoS保证的切换策略研究

针对异构分层无线网络提出了一种保证业务QoS的切换策略。该策略在层间呼叫双向溢出基础上,为实时业务切换设置了保护信道,为非实时业务切换设置了缓冲队列。为了进一步降低实时业务切换的掉线率,还使用了信道侵占技术,原理是实时业务切换呼叫可以侵占数据业务正在使用的信道资源。仿真结果表明,提出的切换方法能够显著降低各类切换业务的掉线率,同时整个异构分层系统的信道利用率也略有提高。     

异构无线网络中动态优先级接纳控制算法研究

针对在应急情况下的异构网络环境中不同类型业务在群组切换时出现的网络拥塞问题,以及现有研究中较少考虑不同类型用户所进行的业务的重要性和紧急性不同,从而不能合理分配有限的网络资源的情况,提出了一种异构无线网络中动态优先级接纳控制算法。首先,根据用户类型和业务类型对业务设定初始优先级;然后,根据业务的执行紧迫性和业务的剩余价值密度对业务优先级进行动态调整,并提出了一种基于业务优先级的抢占调度算法;最后为避免在业务优先级进行动态调整过程中出现颠簸调度现象,给出了避免颠簸调度的条件。所提算法考虑了实际情况中不同用户类型所进行的业务重要程度的不同,对业务进行了优先级设定,使初始优先级高的业务能够优先得到服务,在此基础上为尽量满足整体用户的用网需求,对业务的优先级进行了动态调整。为验证所提方法的有效性,将基于优先级队列调度算法和基于阻塞率约束的群组切换方法作为对比算法,在MATLAB软件环境下进行仿真分析。结果表明,所提方法相较于对比算法能够在减少业务切换的阻塞率的同时,使总体业务的完成率提高10%左右,证明了该算法在使初始优先级高的业务能够优先得到服务的同时,为初始优先级低的业务提供了网络切换的条件,从而提高了网络资源分配的合理性和公平性。     

WDM网络中多优先级动态业务的动态RAW算法

为了解决WDM网络中多优先级动态业务的路由选择与波长分配问题，提出了一种基于分层图模型的动态RAW算法。通过对分层图中波长链路权值的设定，使得连接请求尽量使用空闲的波长链路建立连接，在空闲波长链路不足以建立起连接时，呼叫业务可抢占比其优先级别低的业务的波长链路，且抢占的顺序由低优先级到高优先级，以确保高优先级业务有更低的阻塞率和更好的传输性能，且使得较高优先级业务被中断的可能性较小。     

CDMA网络中综合业务的呼叫接纳控制算法及性能分析

呼叫接纳控制(CAC)是CDMA系统无线资源管理中的重要组成部分,有效的CAC算法能在满足各类业务不同QoS要求的同时,提高资源的利用率。本文对于新呼叫和切换呼叫,提出了一种有效的呼叫接纳控制算法,给予了切换呼叫更高的优先级,并采用Markov链对算法的性能进行了分析。     

LEO卫星中模拟实时通信量确保保护信道的分配

由于LEO（Low Earth Orbit）卫星网络中不断变化的点波束小区实时通信量负载无法估计,提出了一种根据系统仿真过程中当前通信量状态优化动态保护信道算法（ODGCS）。该分配策略引入呼叫间隔时间和切换呼叫中断间隔时间来获悉系统的实时性能状态,由仿真中通信量状态预测当前系统切换呼叫的中断概率,根据比较计算的呼叫中断概率和预先设定的QoS（Quality of Service）值,动态调整预留给切换呼叫使用的保护信道数。仿真结果表明,与传统的静态预留保护信道的算法相比,该算法能有效提高LEO卫星系统的性能稳定性。在负载较轻时,ODGCS算法保证切换呼叫QoS的同时,降低了新呼叫阻塞概率。     

A preemptive channel allocation scheme for multimedia traffic in mobile wireless networks

This paper presents a channel allocation model with both partial and full preemptive capabilities for multimedia traffic in mobile wireless networks. The different types of multimedia traffic in transmitting through next-generation networks possess different characteristics and demand an adequate channel allocation scheme to fulfill individual Quality of Service (QoS) requirements. In the proposed model, multimedia traffic is classified into three classes corresponding to different priority levels in a decreasing order. To effectively reduce the dropping probability, a higher-priority handoff call is allowed to fully or partially preempt any lower-priority ongoing calls when the channel capacity becomes insufficient. In addition, to prevent from possible starvation of the lowest-priority traffic, a portion of system channels are purposely reserved. Performance measures, including the dropping probability of handoff calls, the call-interruption probability that an ongoing call is forced to termination due to full preemption, and the bandwidth reduction ratio due to partial preemption, are investigated through an analytical model built with 4-D Markov chains. The numerical results demonstrate the effectiveness of our model.     

QoS-aware radio resource management scheme for CDMA cellular networks based on dynamic interference guard margin (IGM)

Efficient radio resource management (RRM) for CDMA-based cellular communication systems using the interference guard margin (IGM) scheme is investigated in this work. Two important concepts, i.e., the guard channel (GC) and the load curve (LC), are integrated to derive IGM. The resulting call admission control (CAC) scheme gives preferential treatment to higher priority handoff calls by pre-reserving a certain amount of resource in terms of IGM. A radio resource estimation (RRE) function is implemented in each base station (BS) to assist RRM module to adjust the level of IGM dynamically. RRE in each BS estimates the amount of IGM by considering traffic load in its current cell as well as traffic conditions in neighboring cells. A service model is adopted to support quality of service (QoS) demand of multiple services, which includes mobile terminal’s data rate, different levels of priorities, mobility and rate adaptivity characteristics. Simulations are conducted by OPNET to study performance of the proposed IGM scheme in terms of a defined cost function, new call blocking probability, handoff dropping probability and system utilization, under different traffic conditions.     

An efficient approach for distributed dynamic channel allocation with queues for real-time and non-real-time traffic in cellular networks

We are witnessing these days a rapid growth of mobile users. Therefore, frequency spectrum must be efficiently utilized, as available frequency spectrum is limited. This paper proposes a channel allocation scheme with efficient bandwidth reservation, which initially reserves some channels for handoff calls, and later reserves the channels dynamically, based on the user mobility. The direction of user mobility may not be straight always, but the user may also go left, right or backwards. Thus, QoS can be improved, if the channel reservation is made based upon the user mobility and the location of the user. We devise here a new algorithm that deals with multiple traffic systems by modifying the existing DDCA algorithm [Krishna, P.V., Iyengar, N.Ch.S.N., 2008. Optimal channel allocation algorithm with efficient channel reservation for cellular networks. International Journal of Communication Networks and Distributed Systems 1 (1), 33-51]. This algorithm reserves more channels for hot cells, less number of channels for cold cells and an average number of channels for the medium cells. Furthermore, we maintain queues for all types of calls. We model the system by a three-dimensional Markov Chain and compute the QoS parameters in terms of the blocking probability of originating calls and the dropping probability of handoff calls. The results indicate that the proposed channel allocation scheme exhibits better performance by considering the above mentioned user mobility, type of cells, and maintaining of the queues for various traffic sources. In addition, it can be observed that our approach reduces the dropping probability by using reservation factor.     

无线网络一种新的基于实测的呼叫接入控制算法

提出了一种新的应用于无线网络的呼叫接入控制算法.该算法采用自回归滑动平均(ARMA)直接对切换呼叫掉线数建模,预测下一时刻可能的掉线数目,据此反馈更新资源预留门槛(Th).仿真结果表明,无论是在中业务负载,还是高业务负载下,该算法都能在提高系统统计复用增益(任意时刻系统允许接入呼叫连接数)的同时满足目标掉线概率的要求.     

基于位置服务信息的动态速率切换算法

提出了一种新的无线网络中的基于位置服务信息的动态速率切换算法,根据LBS信息和信号变化矢量判断即将来临的数据切换呼叫并为其预留信道,兼顾数据业务的VBR特性而自适应动态改变其服务带宽。仿真的结果表明,与其他切换算法相比,新算法的呼叫强拆率和呼叫阻塞率均有下降,信道利用率得到提高,提高了无线呼叫接入控制系统的QoS。