多无线电协作技术与异构网络融合

异构网络融合是未来网络技术发展的必然趋势。异构网络的融合面临着高延迟、高消耗、低速率等诸多方面的“瓶颈”。为克服这些“瓶颈”,满足异构网络融合的需求,多无线电协作技术应运而生。通过多无线电间的相互协作和对多无线电资源的有效管理及合理分配,能够有效地提高网络吞吐量,降低无线设备的能量消耗,减少异构网络间切换的延迟,从而为实现真正的异构网络无缝融合提供了可能。     

Performance analysis of multi-user diversity in heterogeneous cooperative communication systems

The heterogeneous cooperative relaying technique can be utilized to complete the hierarchical convergence for the multi-radio access networks, where the single heterogeneous cooperative relay is selected and the maximal-ratio combining (MRC) scheme is utilized to achieve the cooperative diversity gain. In order to evaluate performances of the hierarchical convergence mechanism, this paper theoretically investigates the key factors of the multi-user diversity (MUD) gain, the heterogeneous cooperative diversity gain and the large scale fading of the first and second links. The tight closed-form expressions in terms of the outage probability and the average symbol error rate are derived for evaluating how and with what factors impact on the system performance. The analytical and simulation results show that the number of heterogeneous cooperative relay nodes (HCRNs)M and the number of destination stations (DSs)K have great impacts on performances, and the order of outage probability is (M + 1)K. The large scale fading ratio of the first hop to the second hop also has a big impact on performances. Thus in the real network, we can utilize advanced radio resource management schemes to achieve a high multi-user diversity, instead of configuring too many HCRNs for the heterogeneous cooperative diversity gain. Furthermore, we can guarantee the transmission quality between the BS and HCRNs via the network planning to optimize the overall network performance.     

Downlink energy efficiency modeling and optimization with backhaul awareness and interference price in ultra cellular HetNet

The cellular heterogeneous network(HetNet) with ultra dense small cells is called ultra cellular HetNet.The energy efficiency for this network is very important for future green wireless communications.The data rates and power consumptions for three parts(i.e.,macro cells,small cells,and mixed backhaul links) in ultra cellular HetNet are jointly formulated to model downlink energy efficiency considering the active base stations(BSs) and inactive BSs.Then,in order to decrease the downlink co-channel interference,the interference price functions are also jointly set up for the three parts in ultra cellular HetNet.Next,energy efficiency optimization iterative algorithm scheme using the fractional programming and Lagrangian multiplier with constraints for density of ultra dense small cells and fraction of mixed backhaul links is presented with interference pricing.The convergence and computation complexity are also proved in this scheme.The numerical simulations finally demonstrate convergence behavior of the proposed algorithm.By comparison,some conclusion can be drawn.Maximizing energy efficiency of system is lower as the density of small cell is high.The effect on maximizing energy efficiency with interference price outperforms that without interference price.And the energy efficiency increases as the fraction of mixed backhaul links is higher because of more power consumption in the microwave backhaul links.     

异质节点分离CRSN中MAC协议设计与性能分析

认知无线传感器网络(CRSN)是一种将认知无线电(CR)技术引入传统WSN中的新型网络,具有一定的应用价值和发展前景.然而,CRSN中的认知功能带来的额外能耗和处理要求及其高成本实现,阻碍了它的进一步发展及应用.基于此,提出将认知功能迁移到另外一类节点——认知节点,并使其拥有较强的处理能力和能量收集能力.认知节点与普通传感器节点按照一定比例进行部署,组成另外一种新型网络——异质节点CRSN (HT-CRSN),这种新型网络能够提高网络性能并降低部署成本.并提出了一种能够适用于这种异质节点传感器网络的工作时序及其一系列可行性的MAC协议(FBP等).通过对所提MAC协议的能耗分析,说明可以通过调整两类异质节点的部署比例和能量收集速率均衡两类异质节点的能耗,进而提高网络生命周期.     

Energy efficient cooperative spectrum sensing in wireless multi-antenna sensor network

This paper will address sensor selection problem for spectrum sensing in a cognitive radio network. The sensor’s limited energy is an important issue which has attracted more attention in recent years. An energy efficient cooperative spectrum sensing will hereby be proposed when multi-antenna sensors are used. Two decision-making techniques are utilized for the combination of antennas’ signals in each sensor: hard and soft decision-making. OR rule is used for hard decision-making technique while selection combining, equal gain combining and maximum ratio combining (MRC) are used for the soft one. In each combination scheme, the sensor selection is a problem by means of which both the energy consumption is minimized and the detection performance gets satisfied. The problem is solved based on the standard convex optimization method. Simulation results show the achievement of a significant energy saving compared to the networks using single-antenna sensors specifically in low signal to noise ratio state. Among all methods, MRC combining enjoys the least energy consumption, as well; it satisfies the desired detection performance.     

SMDP-based sleep policy for base stations in heterogeneous cellular networks

A dense heterogeneous cellular network can effectively increase the system capacity and enhance the network coverage. It is a key technology for the new generation of the mobile communication system. The dense deployment of small base stations not only improves the quality of network service, but also brings about a significant increase in network energy consumption. This paper mainly studies the energy efficiency optimization of the Macro-Femto heterogeneous cellular network. Considering the dynamic random changes of the access users in the network, the sleep process of the Femto Base Stations (FBSs) is modeled as a Semi-Markov Decision Process (SMDP) model in order to save the network energy consumption. And further, this paper gives the dynamic sleep algorithm of the FBS based on the value iteration. The simulation results show that the proposed SMDP-based adaptive sleep strategy of the FBS can effectively reduce the network energy consumption.     

面向节点异构的能耗感知虚拟网络映射算法

在底层网络节点异构的环境中,能耗优化的虚拟网络映射问题并不是最小化工作节点和链路数。该文针对此问题,构建底层网络节点和链路的负载能耗模型,并以能耗最优为目标,建立虚拟网络映射问题的数学模型,提出一种能耗感知虚拟网络映射算法。该算法在节点映射阶段以最小化能耗和协调链路映射为原则,将虚拟节点映射至综合资源能力最大的底层节点上,并采用改进的能耗感知k最短路径法进行链路映射。仿真结果表明,该算法显著减少虚拟网络映射的能耗,且底层网络节点异构性越大,能耗优势更为明显。     

Fuzzy chessboard clustering and artificial bee colony routing method for energy‐efficient heterogeneous wireless sensor networks

Energy is an extremely critical resource for battery‐powered wireless sensor networks (WSNs), thus making energy‐efficient protocol design a key challenging problem. However, uneven energy consumption is an inherent problem in WSNs caused by multi‐hop routing and many‐to‐one traffic pattern among sensors. In this paper, we therefore propose a new clustering method called fuzzy chessboard clustering (FFC), which is capable to overcome the bottleneck problem and addressing the uneven energy consumption problem in heterogeneous WSNs. We also propose an energy‐efficient routing method called artificial bee colony routing method (ABCRM) to find the optimal routing path for the heterogeneous WSNs. ABCRM seeks to investigate the problems of balancing energy consumption and maximization of network lifetime. To demonstrate the effectiveness of FCC‐ABCRM in terms of lessening end‐to‐end delay, balancing energy consumption, and maximization of heterogeneous network lifetime, we compare our method with three approaches namely, chessboard clustering approach, PEGASIS, and LEACH. Simulation results show that the network lifetime achieved by FCC‐ABCRM could be increased by nearly 25%, 45%, and 60% more than that obtained by chessboard clustering, PEGASIS, and LEACH, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

On the performance of heterogeneous MANETs

Recent decades have witnessed the birth of major applications of wireless communication technology, further supported by the increasing capabilities of portable devices, low cost and ubiquitous presence. Despite radio technology diversity, a great deal of existing research focuses on a single and isolated wireless technology at a time, where homogeneous elements are identified by IP addresses. This work presents a heterogeneous technology routing (HTR) Framework, targeted towards scenarios where the heterogeneity of devices and networking technologies is present. Our contribution is many fold. It consists of a framework, which encompasses a process for bootstrapping networks, a routing protocol capable of dealing with multiple network interfaces, and a tuning with multipath extensions. We evaluate the performance of the bootstrap, routing and multipath mechanisms by way of simulation and an actual testbed implementation. The multipath evaluation simulates HTR networks with WiMAX, 3GPP LTE and Wi-Fi support. Results show that our proposal can effectively improve the data delivery ratio for ad-hoc networks and that it reduces the end-to-end delay without major impact on network energy consumption. As part of HTR tuning, we investigate next the impacts of tuning the HELLO refresh interval timer on route convergence and its subsequent energy consumption reduction during this phase. We also compare our tuned HTR with the widely used optimized link state routing protocol. Results show that varying the HELLO refresh interval can improve the convergence time and reduce the energy consumption without major impact on network behavior. Our proposal also includes a new distributed address allocation algorithm, namely, the dynamic node configuration protocol (DNCP). This paper conducts a comparative analysis between the Prime, Prophet and the DNCP schemes using static and dynamic topologies in terms of network setup time, energy consumption and control message overhead. Results show that the DNCP had a lower battery power consumption and less control message overhead while it slightly suffers with regard to setup.

     

Increasing network lifetime by balancing node energy consumption in heterogeneous sensor networks

Sensor nodes are powered by battery and have severe energy constraints. The typical many‐to‐one traffic pattern causes uneven energy consumption among sensor nodes, that is, sensor nodes near the base station or a cluster head have much heavier traffic burden and run out of power much faster than other nodes. The uneven node energy dissipation dramatically reduces sensor network lifetime. In a previous work, we presented the chessboard clustering scheme to increase network lifetime by balancing node energy consumption. To achieve good performance and scalability, we propose to form a heterogeneous sensor network by deploying a few powerful high‐end sensors in addition to a large number of low‐end sensors. In this paper, we design an efficient routing protocol based on the chessboard clustering scheme, and we compute the minimum node density for satisfying a given lifetime constraint. Simulation experiments show that the chessboard clustering‐based routing protocol balances node energy consumption very well and dramatically increases network lifetime, and it performs much better than two other clustering‐based schemes. Copyright © 2006 John Wiley & Sons, Ltd.     

大容量光网络异构互联及控管研究

多种类型的网络设备并存造成光网络严重异构化,且难以实现真正意义上的互联互通,成为阻碍光网络进一步发展的＂瓶颈＂。文章针对大容量光网络异构互联及优化控管问题,对一些相关新技术和研究成果进行介绍,包括集中式与分布式相结合的异构多域大规模光网络广义控管架构、K随机最短路域间路由优化技术、基于＂边缘环＂的多域网络拓扑架构、路由重定向信令技术,以及异构多域光网络试验平台搭建等。     

Multiple Routing Configurations for Fast IP Network Recovery

As the Internet takes an increasingly central role in our communications infrastructure, the slow convergence of routing protocols after a network failure becomes a growing problem. To assure fast recovery from link and node failures in IP networks, we present a new recovery scheme called Multiple Routing Configurations (MRC). Our proposed scheme guarantees recovery in all single failure scenarios, using a single mechanism to handle both link and node failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and assumes only destination based hop-by-hop forwarding. MRC is based on keeping additional routing information in the routers, and allows packet forwarding to continue on an alternative output link immediately after the detection of a failure. It can be implemented with only minor changes to existing solutions. In this paper we present MRC, and analyze its performance with respect to scalability, backup path lengths, and load distribution after a failure. We also show how an estimate of the traffic demands in the network can be used to improve the distribution of the recovered traffic, and thus reduce the chances of congestion when MRC is used.     

基于深度强化学习的无人机辅助移动边缘计算系统能耗优化

近年来,部署搭载有移动边缘计算(MEC)服务器的无人机(UAVs)为地面用户提供计算资源已成为一种新兴的技术。针对无人机辅助多用户移动边缘计算系统,该文构建了以最小化用户平均能耗为目标的模型,联合优化无人机的飞行轨迹和用户计算策略的调度。通过深度强化学习(DRL)求解能耗优化问题,提出基于柔性参与者-评论者(SAC)的优化算法。该算法应用最大熵的思想来探索最优策略并使用高效迭代更新获得最优策略,通过保留所有高回报值的策略,增强算法的探索能力,提高训练过程的收敛速度。仿真结果表明与已有算法相比,所提算法能有效降低用户的平均能耗,并具有很好的稳定性和收敛性。     

基于节点移动和协作转发的异构传感器网络路由协议

在异构传感器网络中,超级节点有着重要的意义.针对异构传感器网络中超级节点能量消耗过快的问题,提出了一种新的分簇路由协议（MCC）.通过在建簇阶段采用簇首移动控制策略来使簇内负载更加均衡;在簇间数据传输时引入了节点协作转发机制,提高了分簇协议的数据传输性能.通过NS2仿真验证,结果表明,MCC协议不仅降低了簇首能耗,而且使网络能耗更加均匀,延长了网络寿命.     

容错能量均衡WSN拓扑控制方案研究

针对WSN（Wireless Sensor Net）结构中存在大量的网络覆盖冗余与节点唤醒时间的延长,耗费了资源同样也增加了节点的工作能耗的特点。设计了一个拓扑控制方案,减少网络冗余的同时,兼顾了网络的鲁棒性。并且保证生成拓扑具有最小的能量消耗。该方案根据节点的位置信息。建立各监测节点到簇节点的能量消耗最小并且可以保证...     

Low-Energy Adaptive Unequal Clustering Protocol Using Fuzzy c-Means in Wireless Sensor Networks

Clustering technique in wireless sensor networks incorporate proper utilization of the limited energy resources of the deployed sensor nodes with the highest residual energy that can be used to gather data and send the information. However, the problem of unbalanced energy consumption exists in a particular cluster node in the network. Some more powerful nodes act as cluster head to control sensor network operation when the network is organized into heterogeneous clusters. It is important to assume that energy consumption of these cluster head nodes is balanced. Often the network is organized into clusters of equal size where cluster head nodes bear unequal loads. Instead in this paper, we proposed a new protocol low-energy adaptive unequal clustering protocol using Fuzzy c-means in wireless sensor networks (LAUCF), an unequal clustering size model for the organization of network based on Fuzzy c-means (FCM) clustering algorithm, which can lead to more uniform energy dissipation among the cluster head nodes, thus increasing network lifetime. A heuristic comparison between our proposed protocol LAUCF and other different energy-aware protocol including low energy adaptive clustering hierarchy (LEACH) has been carried out. Simulation result shows that our proposed heterogeneous clustering approach using FCM protocol is more effective in prolonging the network lifetime compared with LEACH and other protocol for long run.     

认知蜂窝网络环境下的上行节能方法研究

针对蜂窝网用户在高速数据传输时能耗过高的问题,基于认知蜂窝网络模型,提出了一种通过合理利用认知网络资源进行多网络并发传输的最大能效传输策略。该策略利用多模终端可以同时接入不同网络进行并发传输的特点,建立用户能效模型,并通过研究并发传输时不同网络可用信道状态、能耗和数据传输速率之间的关系,得出使用户能效最大的认知网络资源使用和数据传输速率分配算法。仿真结果表明,该最大能效策略能够有效提升用户的能效。     

QoS‐aware cross‐domain collaborative energy‐saving mechanism for FiWi virtual networks

The fiber‐wireless (FiWi) access network is a very promising solution for next‐generation access networks. Because of the different protocols between its subnets, it is hard to globally optimize the operation of FiWi networks. Network virtualization technology is applied to FiWi networks to realize the coexistence of heterogeneous networks and centralized control of network resource. The existing virtual resource management methods always be designed to optimize virtual network (VN) request acceptance rate and survivability, but seldom consider energy consumption and varied requirements of quality of service (QoS) satisfaction, which is a hot and important topic in the industrial field. Therefore, this paper focuses on the QoS‐aware cross‐domain collaborative energy saving mechanism for FiWi virtual networks. First, the virtual network embedding (VNE) model, energy consumption model, and VNE profit model of FiWi networks are established. Then, a QoS‐aware in‐region VN embedding mechanism is proposed to guarantee service quality of different services. After that, an underlying resource updating mechanism based on energy efficiency awareness is designed to realize low‐load ONU and wireless routers co‐sleep in FiWi networks. Finally, a QoS‐aware re‐embedding mechanism is presented to allocate proper resource to the VNs affected by the sleeping mechanism. Especially for video VNs, a re‐embedding scheme which adopts traffic splitting and multipath route is introduced to meet resource limitation and low latency. Simulation results show that the proposed mechanism can reduce FiWi network's energy consumption, improve VNE profit, and ensure high embedding accepting rate and strict delay demand of high‐priority VNs.     

Small‐cell planning in LTE HetNet to improve energy efficiency

Cell planning is one essential operation in wireless networks, and it significantly affects system performance and cost. Many research efforts consider the cell planning problem with identical base stations (BSs) or to construct a new network on the region without any infrastructure. However, long‐term evolution (LTE) adopts heterogeneous network, which allows operators to tactically deploy small cells to enhance signal coverage and improve performance. It thus motivates us to propose a small‐cell planning problem by adaptively adding low‐powered BSs with the limitation of budget to an existing network to increase its energy efficiency, which is defined by the ratio of network throughput to the amount of energy consumption of BSs. We consider 2 types of LTE small cells, namely, microcells and picocells, and develop different clustering strategies to deploy these cells. Based on the available resource and traffic demand in each cell, we then adjust the transmitted power of the deployed BS with energy concern. Experimental results demonstrate that our small‐cell planning solution can achieve high‐energy efficiency of LTE networks, which means that BSs can better use their transmitted energy to satisfy the traffic demands of user devices. This paper contributes in proposing a practical problem for cell planning with heterogeneous network consideration and developing an efficient solution to provide green communications.     

Use of wireless system in healthcare for developing countries

Healthcare is one of the major applications of wireless systems that possess crucial issues. Specifically developing countries require a low cost and reliable network with efficient protocols. The most challenging concern of Body Area Network (BAN) is heterogeneity, which requires fairness with reliability among all the network nodes. Solutions proposed for these networks either do not provide fair packet transmission or consume high energy and introduce delays. In this paper, we propose a cross layer protocol for healthcare applications meeting the requirements and challenges of the heterogeneous BAN. The protocol is also feasible for developing countries as it can be implemented over existing wireless infrastructure and provides high network reliability with energy efficiency through cooperation and adaptability. Results show that the proposed scheme improves reliability, throughput, Packet Delivery Ratio (PDR), and energy consumption for scalable and mobile networks over conventional BAN protocols.