移动IP 切换时资源分配动态策略生成机制研究

针对多媒体业务在切换后无法立即获得有保证服务的问题,提出一种移动IP切换时资源管理的动态策略模型,并着重设计模型中动态策略的生成机制。该机制根据移动节点相关预测信息自动生成动态策略,在切换前作准入控制和资源准备。当接入域资源不足时,采用“退却”算法,在保证业务可靠性前提下按优先级灵活调整各业务的资源占有量。分析和仿真表明,该机制能保证较高优先级业务的QoS,提高切换成功率,相对于传统方法更灵活。     

一种基于公平接入的按需动态TDMA协议

针对移动自组织网络(MANET)动态时分多址接入(TDMA)协议的公平性问题,提出了一种基于公平接入的按需动态TDMA协议。节点以一定概率对业务时隙发起申请,根据邻居节点的回复完成时隙占用,通过感知业务量对占用的业务时隙数量进行动态调整。节点获取时隙资源的能力与节点编号以及时隙申请的先后顺序无关。对时隙申请概率以及一个时帧周期内的业务时隙个数进行了分析,给出了最优的参数选择。仿真结果表明相较于其它动态TDMA协议,该协议可以在保证网络吞吐量的同时提高节点接入信道的公平性。     

业务优先级感知的网络流量调度机制

针对网络中业务数据流过大、分布不均匀所造成的网络拥塞,提出一种优先级感知的动态网络流量调度机制.利用令牌桶算法,根据业务优先级的不同为不同业务分配不同速率的令牌,以实现业务优先级的划分;综合考虑业务的优先级及用户节点剩余缓存空间,对不同的业务采取不同的处理方式;同时,以流量到达因素、服务因素及节点缓存为指标定义了一种网络流量调度机制性能指标——分组丢失率.数值结果表明,所提机制可以对网络中业务优先级进行合理的划分,从而有效利用网络资源,预防网络拥塞,提升网络性能,为用户提供更加稳定可靠的网络服务.     

无人机蜂群电磁频谱自主协同半实物仿真研究

针对无人机蜂群在对抗环境下面临的频谱感知能力受限、频谱决策能力不足、环境动态适应能力弱等问题,在不同电磁环境、地形和地貌场景下,通过采用忙闲因子及最优竞争窗口自适应机制,引入半实物仿真,搭建虚拟-真实的无人机蜂群网络,通过MAC层多优先级信道接入算法对无人机系统中多优先级业务的多跳网络信道接入问题进行处理,为突破大规模、高动态场景下无人机蜂群实现面向敌我博弈的用频自主协同决策以及支撑观察、判断、决策、行动(Observation, Orientation, Decision, Action, OODA)全流程应用的动态频谱接入等技术提供了理论与试验支持。     

无线Mesh网络中支持QoS的802.11e协议优化

在无线Mesh网络中,支持QoS的IEEE 802.11eEDCA协议,其固定的队列接入机制,使得在网络负载较重的时高优先业务的QoS得不到应有的保障,同时在网络负载较轻时信道利用率也不高.文中提出了一种动态调整业务接入队列的算法.节点可以根据感知到的网络负载状况自适应调整队列接入方式,在保障高优先级业务QoS要求的同时,尽可能提高信道的利用率.仿真结果表明,在不同网络负载的场景下,该算法相对于IEEE802.11e在QoS保障和利用率方面都有较好的表现.     

确保无线AdHoc网络服务质量的MAC协议研究

本文针对无线局域网中MAC层Qos支持技术进行了研究，在分析了现有的EDCF退避机制的静态参数设置方法的基础上，提出结合网络负载状况动态调节不同优先级业务的竞争窗口和退避时间，改变不同优先级业务的信道接入方式的方法。仿真结果表明，动态调节法相较于静态参数法在网络吞吐量、时延、碰撞率方面都有更好的表现。     

移动无线传感器网络中MAC性能分析及改进

以往无线传感器网络中的媒体接入控制协议主要针对静止网络。当存在移动节点时。协议性能会大幅度降低。对存在移动节点的无线传感器网络中的媒体接入控制协议进行了性能分析，提出了改进算法。仿真结果验证了算法的有效性。最后给出了一种适合移动节点较多的场景的无线传感器网络媒体接入控制协议。     

单兵作战系统中信息监听冲突消除技术研究

针对当前单兵作战系统通信网络中所采用的固定分配TDMA算法不能适应大型战场环境和自组织运行需求的问题,提出一种基于消费算法和二叉树时隙分配算法的动态时隙分配TDMA算法,即C-TDMA算法,通过多组载波监听消除接入冲突,在保证延时的基础上使用消费算法控制节点分组发送量,提高信道接入公平性,同时通过二叉树时隙分配算法支持网络分布式运行。仿真结果表明,对于负载较重、传输混合业务且时延敏感的单兵作战系统网络,该算法可以消除接入冲突,提高信道吞吐率。     

基于802.11e的无线多跳自适应合作式QoS算法

 为解决Ad hoc网络中转发节点拥塞和低优先级业务增多而影响高优先级业务带宽的问题,提出了一种无线多跳网络服务质量保证框架WMHQ(Wireless Multiple Hop QoS)和自适应合作式信道接入算法QAC-EDCA(QoS guaranteed Adaptive Cooperation EDCA).算法将802.11e的优先级区分机制扩展成了三层优先级机制,通过将业务的服务质量需求映射成时隙利用率进行周期性的监测,并以控制帧捎带的方式在两跳范围内传播竞争窗口调整信息,使得高优先级业务具备剥夺低优先级业务带宽的能力和拥塞节点具有协调获取更多带宽的能力.仿真表明,该算法相对802.11e能更好地保护多跳情况下高优先级业务的服务质量.     

避免轻载惩罚支持多业务的EPON动态带宽分配

为了支持语音、视频和数据等多业务接入,以太网无源光网络(EPON)动态带宽分配算法需要保证不同业务的优先级以提供不同的服务质量(QoS)、减小实时业务时间延迟,这会带来轻载惩罚问题.针对该问题,文章提出一种基于多队列带宽分配方案,即光网络单元为不同优先级的业务分别申请带宽并引入预测机制.给出了具体算法并进行了算法仿真.仿真结果表明,该方案不仅能支持语音、视频和数据等多业务接入,还能从根本上避免轻载惩罚,通过预测可以进一步提高高优先级业务的QoS.     

Heterogeneous Network Selection Optimization Algorithm Based on a Markov Decision Model

A network selection optimization algorithm based on the Markov decision process(MDP)is proposed so that mobile terminals can always connect to the best wireless network in a heterogeneous network environment.Considering the different types of service requirements,the MDP model and its reward function are constructed based on the quality of service(QoS)attribute parameters of the mobile users,and the network attribute weights are calculated by using the analytic hierarchy process(AHP).The network handoff decision condition is designed according to the different types of user services and the time-varying characteristics of the network,and the MDP model is solved by using the genetic algorithm and simulated annealing(GA-SA),thus,users can seamlessly switch to the network with the best long-term expected reward value.Simulation results show that the proposed algorithm has good convergence performance,and can guarantee that users with different service types will obtain satisfactory expected total reward values and have low numbers of network handoffs.     

Energy‐aware dynamic task offloading and collective task execution in mobile cloud computing

There is a good opportunity for enlightening the services of the mobile devices by introducing computational offloading using cloud technology. Offloading is a process for managing the complexity of the mobile environment by migrating computational load to the cloud. The mobile devices oblige the quick response for the offloading requests; it is dependent on network connectivity. The cloud services take long set‐up time irrespective of network connectivity. In this paper, new system architecture for the dynamic task offloading in the mobile cloud environment is proposed. The architecture includes the offloading algorithm that concentrates on energy consumption of the tasks both in the local and remote environment. The proposed algorithm formulates a collective task execution model for minimizing the energy consumption. The architecture concentrates on the network model by considering the task completion time in three different network scenarios. The experimental results show the efficiency of the suggested architecture in reducing the energy consumption and completion time of the tasks.     

基于优先级信道预留的快速动态信道分配算法

针对TD-SCDMA系统现有快速动态信道分配算法的不足,提出了一种基于优先级信道预留的快速动态信道分配算法.该算法根据接力切换用户的移动台属性设定不同的优先级,为接力切换呼叫预留信道,结合小分组借用算法,增加了可移动边界动态信道分配(MB DCA)策略的灵活性.仿真结果表明,此算法相对于混合数据速率、小分组借用(MRG,mixed-data rate grouping borrowed)MB DCA算法,实现了VIP和快速移动切换用户的优先接入,有效地降低了切换呼叫的阻塞率,提高了数据业务性能和系统的信道利用率.     

Advanced cellular Internet service (ACIS)

The public's desire for mobile communications and computing, as evidenced by the popularity of cellular phones and laptop computers combined with the explosive demand for Internet access suggest a very promising future for wireless data services. The key to realizing this potential is the development and deployment of high-performance radio systems. In this article we describe a basic service concept, advanced cellular Internet service (ACIS), and the technologies for achieving reliable high-speed transmission to wide-area mobile and portable cellular subscribers with very high spectrum efficiency. Such a wireless service, optimized to meet the needs of a client-server model for information retrieval and Web browsing, and combined with evolutionary enhancements in second-generation technologies, can provide an attractive option for third-generation systems. The radio link design combines OFDM with transmit and receive antenna diversity and Reed-Solomon coding to overcome the link budget and dispersive fading limitations of the cellular mobile radio environment. For access, a dynamic packet assignment algorithm is proposed which combines rapid interference measurements, priority ordering, and a staggered frame assignment schedule to provide spectrum efficiencies of two-to-four times existing approaches     

基于自相似流量水平分级预测的网络队列调度算法

网络流量的自相似特性会导致网络中数据的突发状态持续,为有效降低网络流量突发引起的队列排队时延和分组丢失率,提高不同优先级业务的传输能力,保障业务服务质量需求,提出了一种基于网络流量自相似特性的队列调度算法——P-DWRR。该算法设计了基于自相似流量水平分级预测结果的动态权值分配方法及服务量子更新方法,并根据业务优先级和队列等待时间确定队列的服务次序,以减小数据分组排队时延,降低分组丢失率。仿真结果表明,P-DWRR算法在满足网络不同业务优先级要求的基础上,降低了数据分组的排队时延、时延抖动和分组丢失率,性能优于DWRR和VDWRR。     

Seamless vertical handoff using modified weed optimization algorithm for heterogeneous wireless networks

In the global scenario, a variety of wireless access networks are available. Different types of applications such as real time, nonreal time, and high bandwidth availability are used for heterogeneous wireless networks. Therefore, it is necessary for a service provider to make an appropriate connection support. For better performance, connections are to be exchanged among the different networks using seamless vertical handoff (VHO). The proposed algorithm shows the effect of optimization technique, which involves handoff decision process using vertical handoff triggering and selection of the network. The handoff triggering is initiated by using the received signal strength (RSS). In traditional method, handoff triggering is initiated by using RSS only. This method, modified weed optimization (M-WO) algorithm, reduces the unnecessary handoff by considering both RSS and velocity of the mobile node in handoff triggering. The parameters such as battery lifetime, handoff call dropping rate, load, dynamic weights adaptation and so on are to be considered individually or combined to make an effective network selection process. This paper highlights a novel effect ofM-WOalgorithm for decision making during the VHO. Our effort is to essentially optimize the system load, so that it reduces the handoff call dropping rate and the battery power consumption of the mobile node (MN). Weight of each QoS metrics is adjusted along with the networks changing conditions to trace the M-WO. Therefore, the novel VHO decision-making algorithm is superior to the existing SSF and OPTG methods. The simulation results show that the performance ofM-WOalgorithm is far better than SSF andOPTGmethods in terms of load, handoff call dropping rate and battery lifetime of MN.     

GRA Based Network Selection in Heterogeneous Wireless Networks

4G wireless networks will integrate heterogeneous technologies such as Wireless LAN and third generation (3G) cellular networks and have the capability to offer various services at any time as per user requirements, anywhere with seamless interoperability at affordable cost. One important challenge in such a heterogeneous wireless environment is to enable network selection mechanisms in order to keep the mobile users always best connected anywhere and at any time. In this paper, a multi-criteria access network selection algorithm is proposed in Worldwide Interoperability for Microwave Access–Wireless Fidelity environment, in order to facilitate the provision of high quality services and at the same time to satisfy different types of user service level agreements. Analytical hierarchy process (AHP) and grey relational analysis (GRA) methods are applying for optimal access network selection. The proposed methodology combines the AHP to decide the relative weights of criteria set according to network’s performance, as well as the GRA to rank the network alternatives. The advantages of the GRA method are that the results are based on the original data, the calculations are simple and straightforward, and finally it is one of the best methods to make decision under heterogeneous wireless network environment.     

Optimized Access Network Selection in a Combined WLAN/LTE Environment

Multimode terminals equipped with multiple radio access technologies are becoming increasingly popular. At the same time, network operators and service providers seek opportunities to deliver seamless services cost effectively, leveraging a variety of radio access technologies using both licensed and unlicensed spectrum. In order to standardize the operations of such complex environments 3GPP is currently working on IP flow mobility and mobile data offload solutions. This article proposes and evaluates a new access network selection procedure in such a combined WLAN/LTE environment. The proposed solution takes not only parameters available in the mobile node and its current and candidate access networks into account, but performs an optimization on the heterogeneous wireless network level as well. An optimization model based on an approximate solution to the well-known bin packing problem is presented. Also, there is a signaling scheme for distribution handling presented. Results from simulations performed in OPNET Modeler show improvements compared to basing handover decisions on locally available information only.     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

认知 mesh 网络服务区分的动态频谱接入策略

动态频谱接入策略是实现认知无线电网络高效利用频谱的关键。与传统认知无线电网络不同,认知mesh网络中不同QoS需求的多类型业务共同接入,为适应这一特点,提出服务区分的动态频谱接入策略。策略依据业务的QoS需求确立优先级,针对不同优先级业务采取不同的信道接入方案,实时业务依据最优传输延迟期望选择接入信道集合,在减小传输延迟的同时降低数据传输过程授权用户出现的概率,普通业务选择最优理想传输成功概率的信道,降低信道切换概率。理论与实验结果表明,与传统的认知网络频谱接入策略相比,提出的策略能提供不同业务的服务区分,满足实时业务的低延迟需求,降低数据传输的中断率,同时在授权信道空闲率与网络负载较大时吞吐量性能较优。