GSM系统合法侦听体系结构研究和设计

在分析了合法侦听原理的基础上分析了合法侦听的接口HI1,HI2,HI3三种不同接口实现不同的功能。HI1主要实现鉴权, HI2主要实现被侦听用户的活动信息传送,HI3则是实现被侦听用户的通信内容的传送。根据三种接口给出了GSM系统的合法侦听体系结构和实现GSM合法侦听的系统模型。     

LTE到WCDMA CSFB特殊场景分析

介绍了LTE到WCDMA CSFB语音方案的基本原理和网络要求。重点研究了无合适WCDMA小区场景下各种CSFB语音方案的性能。最后分析了网络开启快速回落功能用户通话结束后的用户感受。     

基于速度触发的提前切换算法在LTE-R中的应用研究

随着高铁的快速发展,铁路移动通信系统对切换时延、切换成功率等要求更为苛刻。该文针对铁路长期演进(LTE-R)系统提出基于速度触发的提前切换算法,通过提前进行信令交互、设置切换预承载点切换的方式抑制过早或过迟切换所带来的通信中断、掉话等问题。通过信令流程图进行理论分析,并对长期演进(LTE)各结构类型数据计算可知,该算法均可缩短切换时延,其中TDD帧结构类型2时效果最为显著。最后通过仿真对比得到提前切换算法相比传统切换算法有着更高且更稳定的切换成功率,验证算法的有效性,为LTE-R在未来铁路专网的应用提供技术支持。     

基于层次化网络编码的无线物联网协作切换机制

该文针对无线物联网中的多路径、多中继切换场景,提出了一种基于层次化网络编码(HNC)的协作切换机制。HNC机制在传统实用网络编码的基础上,利用中继节点距离网络接入点的跳数差异,引入了多层中继圈的思想,对网络进行分层。通过位于不同网络层次的中继节点的相互协作,建立移动终端与远程网络接入点之间的切换连接。HNC机制使移动终端在移动过程中可以保持可靠的切换连接。     

一种基于协作分集技术的切换机制

现有切换管理机制主要采用基于提前切换准备的方法来降低切换过程中的服务中断时间,但是这类切换机制对移动预测算法具有很高的依赖性,因而实际部署的效果不佳。为解决该问题,该文提出了基于协作分集技术的切换机制,通过在切换过程中引入异构协作分集,延长了切换过程中源基站能够为移动终端提供服务的时间,降低对移动预测算法的依赖,从而很好地解决了现有移动管理机制的不足。     

移动IPv6概述

文章分析了IPV6支持移动性的优势，概述了移动IPv6协议，并对一些热点问题，如快速切换、平滑切换、移动管理、AAA和服务质量等进行了探讨。     

Integrated power and handoff control for next generation wireless networks

In this paper, joint downlink power control and handoff design is formulated as optimization problems that are amenable to dynamic programming (DP). Based on the DP solutions which are impractical, two new algorithms suitable for next generation wireless networks are proposed. The first one is an integrated hard handoff/power control scheme that endeavors a tradeoff between three performance criteria: transmitted power, number of handoffs, and call quality. The second is a soft handoff/power control algorithm that also takes into account the additional cost of utilizing soft handoff. The proposed algorithms present a paradigm shift in integrated handoff/power control by capturing the tradeoff between user satisfaction and network overhead, therefore enjoy the advantages of joint resource allocation, and provide significant improvement over existing methods. The achievable gains and the tradeoffs in both algorithms are verified through simulations.

A Guard Code Scheme for Handover Traffic Management in WCDMA Systems

A key performance indicator of mobile wireless networks is failure probability of handover calls. In this paper, we propose a Call Admission Control policy which prioritizes handover calls over new calls in WCDMA systems. The OVSF code occupancy of the system is modeled by a Markov chain and the differentiation between handover and new calls is performed at the code level by introducing a “guard code” scheme. The scheme belongs to the well-known family of guard channel schemes and reserves some code capacity to favor the continuation of handover calls over the new calls. As the management of the general case is intractable, we solve certain numerical instances of the problem and manage to calculate several performance metrics like new call blocking and handover failure probabilities and code utilization. We complete our study with simulation results in the case of higher OVSF code tree capacity.

TD-LTE集群通信系统中基于小区筛选和AHP的切换算法研究

为了提高TD-LTE集群通信系统中用户的切换成功率以及降低阻塞率,文章根据TD-LTE及集群通信的特点,提出一种基于小区筛选(Filtration)机制结合层次分析法(Analytic Hierarchy Process)的切换算法(FAHP)。该算法在利用筛选机制保证目标小区满足通信需求的情况下,结合层次分析法选择出合理的目标小区。仿真分析结果表明,与传统的切换算法相比,该算法能有效提高用户的切换成功率,降低系统的阻塞率。     

一种ANDSF获取接入网动态信息的方法

下一代异构无线网络环境是宽带移动无线接入和异构分布的网络,如何减少切换时延实现无缝切换是当前需要解决的问题。文章针对在切换之前如何获取有效的接入网信息提出了一种新的方法,即一种ANDSF(接入网发现和选择功能)获取接入网动态信息的方法,该方法可以保证ANDSF中接入网信息及时准确。然后介绍ANDSF功能实体,分析其工作原理,指出其不足,并提出改进方法。