改进的IEEE802．16e睡眠模式算法

IEEE802．16e标准采用睡眠模式降低移动台的能量消耗。提出一种改进的睡眠模式控制算法,该算法根据接入速率的变化动态调整睡眠模式的睡眠周期。在给出的4种实际模型上比较IEEE802．16e标准算法与改进算法,结果表明改进算法在低接入速率下能节约更多能量,在高接入速率下与标准算法的性能相当。     

On the effectiveness of single and multiple base station sleep modes in cellular networks

In this paper we study base station sleep modes that, by reducing power consumption in periods of low traffic, improve the energy efficiency of cellular access networks. We assume that when some base stations enter sleep mode, radio coverage and service provisioning are provided by the base stations that remain active, so as to guarantee that service is available over the whole area at all times. This may be an optimistic assumption in the case of the sparse base station layouts typical of rural areas, but is, on the contrary, a realistic hypothesis for the dense layouts of urban areas, which consume most of the network energy.     

基于流量的自组网休眠管理算法

休眠管理作为自组网中节省能量的一种有效方法,正在被广泛的关注.休眠管理通过关闭节点射频,减少空闲状态能量消耗,有效延长了网络生存时间,提高了网络吞吐量;但是常常带来端到端延时增加和递交成功率降低等问题.针对这些问题,提出一种休眠管理算法TSM,各节点根据历史数据流量独立判断是否休眠,利用RTS丢失发现无法通信的邻居节点.NS-2仿真实验表明,相比基于MAC 802-11的AODV,在网络低负载情况下,TSM大幅延长网络生存时间,提高网络吞吐量;无论网络负载高低,TSM对端到端延时和递交成功率的影响很小.     

Availability of end-to-end ideal QoS in IP packet networks

Network processor technology has advanced to the point where high-precision time-based store-and-forward logic is readily incorporated into packet switches and routers. With appropriate scheduling, packets from multiple flows can be serviced without contending for link resources. Accordingly, packet flows traversing a network of switching elements can have both path and time determinacy attributes which support ideal end-to-end QoS (zero jitter, zero loss, acceptable end-to-end latency) for real-time UDP packet flows and guaranteed goodput for TCP flows. One approach to packing a network with a relatively large number of such deterministic flows, i.e. achieving high availability of the ideal QoS service in a network, uses precise buffering of packets at each switch, which introduces latency. This paper describes analysis methods for quantifying how much buffering may be necessary to achieve high (99.999%) availability. For typical network topologies the analysis shows that buffering latency requirements are very small compared to transport delays, even when the network is highly utilized with heterogeneous (e.g. voice, video, circuit emulation, and data) traffic. Actual physical implementations have empirically validated the analysis results as well as the scalability of the end-to-end, time-based forwarding approach and the end-to-end availability of ideal QoS services in IP packet networks.     

Zero-Degree algorithm for Internet GateWay placement in backbone wireless mesh networks

Internet GateWays (IGWs) are responsible for connecting the backbone wireless mesh networks (BWMNs) to the Internet/wired backbone. An IGW has more capabilities than a simple wireless mesh router (WMR) but is more expensive. Strategically placing the IGWs in a BWMN is critical to the Wireless Mesh Network (WMN) architecture. In order to solve the problem of IGWs placement in BWMNs, a novel algorithm is proposed in this paper. The new algorithm is involved in placing a minimum number of IGWs so that the Quality of Service (QoS) requirements are satisfied. Different from existing algorithms, this new algorithm incrementally identifies IGWs and prioritively assigns wireless mesh routers (WMRs) based on the computed degree of WMRs to identified IGWs. Performance evaluation results show that proposed algorithm outperforms other alternative algorithms by comparing the number of gateways placed in different scenarios. Furthermore, having control of the distribution of IGWs in order to locate them closest to available Internet/wired network connection points is an added advantage of this algorithm.     

最大化中心模式和微小模式生成对抗网络

为了解决生成对抗网络（GAN）在生成图像时出现的模式崩塌问题,提出了一种最大化中心模式和微小模式损失生成对抗网络（MMMGAN）。首先,将具有相同标签的生成图像的模式定义为中心模式和微小模式,中心模式和微小模式分别代表相似模式的集合和学习完中心模式后可能的模式变化。其次,基于上述的定义提出最大化中心模式和微小模式损失。最后,引入该损失函数,在保证生成图像的分布逼近真实图像的前提下,绝大多数评价指标都得到了改善,提升了生成图像的多样性。拓展性的实验结果表明,提出的最大化中心模式和微小模式损失应用于两种及其以上不同类型任务中,模式崩塌得到了有效缓解。     

Capacity requirements of traffic handling schemes in multi-service networks

This paper deals with the impact of traffic handling mechanisms on capacity for different network architectures. Three traffic handling models are considered: per-flow, class-based and best-effort (BE). These models can be used to meet service guarantees, the major differences being in their complexity of implementations and in the quantity of network resources that must be provided. In this study, the performance is fixed and the required capacity determined for various combinations of traffic handling architectures for edge-core networks. This study provides a comparison of different QoS architectures. One key result of this work is that on the basis of capacity requirements, there is no significant difference between semi-aggregate traffic handling and per-flow traffic handling. However, best-effort handling requires significantly more capacity as compared to the other methods.     

面向目标跟踪的传感器网络睡眠调度协议

移动目标跟踪是无线传感器网络中的一项重要应用,将睡眠调度机制引入到目标跟踪算法中可以大大降低能耗。针对目标跟踪的实际需求,提出一种面向目标跟踪的传感器网络睡眠调度协议。根据目标跟踪不同阶段,分别设计了目标跟踪前和跟踪过程中传感器节点的睡眠调度机制;另外给出了目标丢失时,如何唤醒节点继续跟踪目标的调度策略。结果表明:该算法能够在保证跟踪质量的同时,降低跟踪能耗。     

Network protection codes: Providing self-healing in autonomic networks using network coding

Agile recovery from link failures in autonomic communication networks is essential to increase robustness, accessibility, and reliability of data transmission. However, this must be done with the least amount of protection resources, while using simple management plane functionalities. Recently, network coding has been proposed as a solution to provide agile and cost efficient self-healing against link failures, in a manner that does not require data rerouting, packet retransmission, or failure localization, hence leading to simple control and management planes. To achieve this, separate paths have to be provisioned to carry encoded packets, hence requiring either the addition of extra links, or reserving some of the resources for this purpose.In this paper we introduce self-healing strategies for autonomic networks in order to protect against link failures. The strategies are based on network coding and reduced capacity, which is a technique that we call network protection codes (NPC). In these strategies, an autonomic network is able to provide self-healing from various network failures affecting network operation. Also, network protection codes are extended to provide self-healing from multiple link failures in autonomic networks. Although this leads to reducing the network capacity, the network capacity reduction is asymptotically small in most cases of practical interest. We provide implementation aspects of the proposed strategies, derive bounds and show how to construct network protection code. The paper also develops an Integer Linear Program formulation to evaluate the cost of provisioning connections using the proposed strategies, and uses results from this formulation to show that it is more resource efficient than 1 + 1 protection. A simulation study to evaluate the recovery times, and the buffering requirements due to network coding is also conducted using the OPNET simulator.     

Coding- and interference-aware routing protocol in wireless networks

Network coding is considered as a promising technique to increase the bandwidth available in a wireless network. Many studies show that network coding can improve flow throughput only if an appropriate routing algorithm is used to identify paths with coding opportunities. Nevertheless, a good routing mechanism is very difficult to develop. Existing solutions either do not estimate the path bandwidth precisely enough or cannot identify the best path in some situations. In this paper, we describe our coding-aware routing protocol that provides a better path bandwidth estimate and is able to identify high throughput paths. Extensive NS2 simulations show that our protocol outperforms existing mechanisms.     

Random and Periodic Sleep Schedules for Target Detection in Sensor Networks

We study random and periodic sleep schedules from the point of view of delay in detecting the target.We consider sleep schedules in which a sensor in"inactive"mode wakes up either randomly or periodically to detect presence of the target within its vicinity resulting into two sleep schedules:(a)random wake-up schedule,and(b)periodic wake-up schedule respectively.Specifically,we analyse and obtain for the random wake-up schedule the expected delay in detection, and the delay,such that with probability P,the delay is less than the computed value.For the periodic wake-up schedule we show that there exists an upper bound on the delay.Further we compute the average value of delay.We have shown that the theoretically computed averages and the upper bounds on the delay match with the simulation results for the random wake-up and periodic wake-up schedules.     

Radio planning of energy-aware cellular networks

This paper introduces a joint planning and management optimization approach for cellular networks to limit energy consumption while guaranteeing QoS and minimizing operators Capex and Opex. The modeling framework shows that an effective energy-efficient operation depends on the planning decisions. Conversely, it also shows that planning with energy management operation in view yields more versatile topologies than more traditional models based only on Capex. Results for LTE networks are provided and show that savings up to 65% in energy expenses are possible with slight increases in capital investments.     

基于预约调度的无线传感器网络的MAC协议

提出了一种基于预约调度的用于无线传感器网络的MAC协议--SSMAC.该协议采用分布式竞争接入和预约调度发送,提供高能量效率的信道接入和支持QoS业务的传输,较好地解决了隐藏终端和暴露终端问题.仿真结果表明SSMAC协议在保持节能的同时,在降低媒体接入时延、提高报文投递成功率和提供QoS保障上较TRAMA协议性能有很大的提高.     

无线传感器网络能量管理研究

传感器节点能量受限的特点使能量管理成为无线传感器网络(WSNs)设计的一个重要内容。对近年来无线传感器能量管理的研究进展进行了讨论和综述,指出了WSNs能量管理面临的问题与挑战。在分类阐述和比较当前具有代表性的各种休眠机制的同时,介绍了动态电压调节、动态功率管理、数据融合等能量管理策略。最后,指出了WSNs能量管理的未来发展方向。     

无线自组织网络中的服务质量控制

自组织网络是未来无线通信系统中的重要组成部分,随着用户多媒体业务需求的不断增长,服务质量控制成为自组织网络研究中不可避免的问题。根据目前的研究结果,总结分析了在无线自组织网络中进行服务质量控制设计的基本思想,包括系统模型、信令协议、路由算法、MAC层算法等,并讨论了其未来发展方向。     

小波包能量谱在睡眠分期中的应用

利用小波包技术,根据脑电信号在不同睡眠状态下各脑电节律所占的成分不同,提出一种基于小波包能量谱的睡眠脑电分期方法。首先依据脑电信号各节律的频率特点选择好分解层数对信号进行小波包分解,再重构信号,提取出睡眠脑电信号的各节律;然后运用小波包能量谱计算各节律所占的能量比重;最后用3例脑电数据进行实验。实验结果表明,不同睡眠状态下各脑电节律所占比重不同,随着睡眠的深入,睡眠脑电节律θ和δ所占的能量比重增大,而节律α和β所占的比重在减少。因此,可以运用睡眠脑电信号中各节律所占的成分不同来区分不同的睡眠状态,并可作为睡眠分期的一个特征参数。     

IEEE 802.16e休眠模式算法的研究和改进

IEEE 802.16e为移动站点提供了大范围的无线接入,为了减少移动站点的功率消耗,它提出了一种节能机制休眠模式.移动站点在休眠间隔后进入监听间隔,检查其间是否有数据分组到达.如果有,它将进入清醒状态接收数据,否则,继续进入休眠间隔.草案中所提出的休眠模式指数增长算法在低业务量情况下,响应时间过长.文中提出了线性增长算法解决这一问题,理论分析了该算法的两个性能指标平均响应时间和平均能量消耗.并结合仿真实验,对比了这两种算法的性能,证实了后者具有较好的性能.进一步分析了休眠模式各个参数对上述两个性能指标的影响,对参数值的选取有重要帮助.     

无线传感器网络S-MAC协议能量有效性改进

针对无线传感器网络中节点能量受限的特点,对目前典型的无线传感器网络信道接入协议(S-MAC)的休眠机制进行了改进.改进后的协议(ES-MAC)根据传感/转发事件发生间隔的变化而自适应调整各节点的休眠时长以节省空闲监听的能量消耗,从而延长整个网络的生存时间.仿真结果表明,在传感/转发事件发生间隔较长的情况下,改进后的协议能够很好地工作,并提高了原协议的能量有效性.     

A new integrated energy-saving scheme in green Fiber-Wireless（FiWi） access network

Energy savings in Internet have been regarded as a significant technical issue for academic and industrial community.Particularly,access network accounts for more than 70%of the total energy consumption of Internet.As a promising access technique,Fiber-Wireless(FiWi)network not only enables the cost-effective broadband access,but also provides more opportunities for energy savings.Previous works mostly focused on the energy savings in the optical back-end of FiWi.Generally,they extended the Optical Network Unit(ONU)sleep mechanisms initially designed for Passive Optical Network(PON)to FiWi by combining with the wireless rerouting.However,most of these works left the energy savings in the wireless front-end untouched.In fact,when one or more ONUs in the network is/are sleeping,many wireless components remain idle or underutilized which cause a lot of energy waste.Motivated by this,we propose a new integrated Wireless-Optical Energy Savings(WOES)scheme for the comprehensive energy savings in FiWi.The WOES scheme consists of two interactive modules,Energy-Efficient ONU Management(EEOM)and Energy-Aware Topology Configuration(EATC).EEOM aims at the energy savings in the optical back-end by putting the low-load ONUs into sleep state.A pair of thresholds is introduced into EEOM to maintain the states of ONUs.As soon as ONUs states change,EATC will reconfigure the wireless topology by putting the idle Radio Interfaces(RIs)into standby state,thus minimizing the energy consumption of the wireless front-end.Simulation results show that the WOES scheme can reduce the energy consumption significantly with just a little performance degradation in network throughput and end-to-end delay.