基于相对移动性预测的k跳AdHoc网络分簇算法

针对网络节点随机移动造成的AdHoc网络分簇结构变化和路由失效问题,该文提出一种基于相对移动性预测的k跳分簇算法,分析和预测网络节点运动状态,自适应地调整分簇结构,提高簇结构稳定性。首先,使用多普勒频移计算节点间相对移动速度,预测节点移动性,得到节点间链路保持时间。然后,在簇形成阶段,采用面向节点稳定性的MAX-MIN启发式算法,根据节点的平均链路保持时间对簇首进行选择。进而,在簇保持阶段,提出一种基于节点运动状态的网络自适应调整算法,一方面调整节点信息数据发送周期以平衡数据开销和精确度,另一方面通过预测节点间链路通断情况调整分簇结构,以减少链路失效时的链路重建时间,提高网络运行质量。仿真实验表明,所提算法可以有效延长簇首持续时间,提高簇结构在动态环境下的稳定性。     

高动态无线自组网路由协议设计

针对节点快速移动过程中网络建立时间较长,数据端到端传输时延无法得到可靠保 障,并且由于维护动态网络连接性造成网络开销较大等方面的问题,提出了一种无线自组网 路由协议,通过分簇算法快速将网络分为多个簇,每个簇包括簇首节点、成员节点和簇间网 关节点。该协议能够应用于快速移动节点构成的高动态无线自组织网络中,实现了先应式和 反应式路由算法进行了有机结合,能够在快速变化的拓扑结构中为未知路由提供优化的路由 结果,利用较小的网络开销实现网络快速构建和数据端到端的实时传输。     

基于半固定分区的无线传感器网络分簇算法

经典分簇路由算法在每轮的数据采集过程中均需要重新选举簇头和簇的划分,使得网络的拓扑结构极不稳定以及增加了不必要的网络开销,因此提出了一种基于半固定分区的无线传感器网络分簇算法.该算法在首轮,对传感器网路进行簇头的随机选举和簇的划分且其它轮不再重新分簇,然后在各个簇内依据节点的剩余能量和到汇聚节点的距离进行簇头的选举.实验结果表明,与传统分簇协议中的全网广播簇头选举机制相比,该算法不仅拥有稳定的簇结构,而且网络工作稳定期延长了约69.62%,有效地提高了无线传感器网络的可靠性.     

基于信誉度的移动自组网入侵检测分簇算法

针对已有基于路由的分簇算法,不适用于移动自组网入侵检测的特性要求,文中提出了一种基于信誉度的入侵检测分簇算法(CIDS).该算法从簇结构安全、稳定的角度出发,采用信誉度的概念对网络节点属性进行数学抽象,定义了节点信誉度的数学表达式,选择综合信誉度高的节点收集网络教据、检测网络行为.为移动自组网入侵检测系统提供了稳定、安全的支持.     

分簇无线传感器网络动态时隙分配MAC协议

为降低大规模无线传感器网络的平均能耗,提出了一种基于动态分配的调度型无线传感器网络MAC协议（SDC-MAC）。该协议簇间使用FDMA方式分配无线信道,簇内通过TDMA方式给各个节点分配可变长的时隙。随着簇结构的变化,簇头通过时隙分配通知,对簇内节点的时隙分配进行动态调整,簇成员节点则根据控制信息进行休眠和唤醒。仿真结果显示,该算法有效地降低了网络的平均能耗,当网络流量高时还可降低平均数据包时延。     

面向稳定性和负载均衡的Ad hoc分簇算法

Ad hoc网络是一种移动设备通过无线连接的移动自组织网络。分簇算法被证明是管理自组织网络资源的有效方法。因此,一个更加稳定的分簇结构对整个网络的性能将会产生直接的影响。文章提出了一种面向稳定性和负载均衡的分簇算法SLCA（Stability-oriented and Load-balanced Clustering Algorithm）,这种算法通过改善节点度和在簇维护阶段引入蒙特卡洛思想的方法,提高了簇的稳定性和负载均衡。通过仿真,结果显示SLCA算法的性能相比NWBCA较优越。     

移动自组织网络预测分簇算法的路由协议

针对移动自组织网络中传统分簇算法存在稳定性低、网络开销大的问题,在WCA分簇算法的基础上,提出一种带有预测机制的EWCA-MP(Efficient on-demand Weighted Clustering Algorithm using Mobility Prediction)分簇算法,该算法在簇头选择时充分考虑节点间的链路保持时间,在簇维护阶段引入模糊逻辑的概念,对Hello消息包的广播周期进行优化。并将其应用于CBRP中,提出了一种ECBRP-MP(Efficient Cluster Based Routing Protocol using Mobility Prediction)移动预测的分簇路由协议。仿真结果表明,EWCA-MP算法在簇头数目、单位时间内节点转移次数和统治集更新次数明显减少,ECBRP-MP路由协议在路由开销、分组投递率的性能得到优化。     

基于区域的车载自组织网络节点分簇算法研究

针对车载自组织网络复杂的应用场景,提出了一种基于区域的网络分簇算法(ZACA)。将道路环境划分为路段区域(Segment)和路口区域(Intersection)分别计算节点的链路连通时间和连接度,并结合区域位置和传统综合权重的WCA分簇算法,实现不同道路模型下簇头的推举和分簇维护。仿真证明该算法能够有效地适应车载网络环境,能提高簇的稳定性、减少分簇开销,具有更高的稳定性。     

MANET网络分簇组网协议比较与分析

基于分簇结构的MANET网络不依赖固定基础设施即可以实现动态组网与数据传输,可以通过跨簇节点实现大规模组网。对分簇组网协议与算法进行了分析与介绍,在此基础上基于最大连接度算法提出了一种解决分簇组网中跨簇处理的双信道跨簇策略。最大连接度算法能够在保障网络的稳定性的同时提高跨簇通信的效率,双信道跨簇处理有利于实现网络的分层管理与控制,组成与逻辑关系一致的实体网络,网络之间在保持通联的同时具备较高的独立性,传输效率更高。     

异构无线传感器网络中簇首的优化部署策略

分簇对用于环境监测的无线传感器网络具有较好的适应性和节能性,由高能力节点担任簇首可以更好地实现节能并改善网络性能.在大规模网络中,高能力簇首部署问题是一类NP-hard问题.同时考虑了影响网络性能的簇半径和簇首的容量限制,把簇首的优化部署问题形式化为一个整数规划问题.针对该问题,提出了启发式的基于K-平均和模拟退火混合算法的KMSA算法,对簇首节点进行有策略的部署.仿真结果表明,在不同的网络规模和簇个数情况下,KMSA可以改善网络性能.     

Channel access-based self-organized clustering in ad hoc networks

An ad hoc network is a self-organized and distributed entity consisting of a number of mobile stations (MS) without the coordination of any centralized access point. Clustering is one of the fundamental problems in ad hoc networks. In this context, we describe a distributed clustering algorithm for multihop ad hoc networks. We first propose a randomized control channel broadcast access method to maximize the worst-case control channel efficiency, based on which a distributed clustering algorithm is proposed. Both theoretical analysis and simulations indicate that the proposed clustering algorithm takes much less time and overhead to cluster a given network with more stable cluster structure, while incurring very small maintenance overhead in a dynamic network resulting from the mobility of the MS.     

Stability‐aware multi‐metric clustering in mobile ad hoc networks with group mobility

Clustering can help aggregate the topology information and reduce the size of routing tables in a mobile ad hoc network (MANET). The maintenance of the cluster structure should be as stable as possible to reduce overhead and make the network topology less dynamic. Hence, stability measures the goodness of clustering. However, for a complex system like MANET, one clustering metric is far from reflecting the network dynamics. Some prior works have considered multiple metrics by combining them into one weighted sum, which suffers from intrinsic drawbacks as a scalar objective function to provide solution for multi‐objective optimization. In this paper, we propose a stability‐aware multi‐metric clustering algorithm, which can (1) achieve stable cluster structure by exploiting group mobility and (2) optimize multiple metrics with the help of a multi‐objective evolutionary algorithm (MOEA). Performance evaluation shows that our algorithm can generate a stable clustered topology and also achieve optimal solutions in small‐scale networks. For large‐scale networks, it outperforms the well‐known weighted clustering algorithm (WCA) that uses a weighted sum of multiple metrics. Copyright © 2008 John Wiley & Sons, Ltd.     

A novel weighted clustering algorithm in mobile ad hoc networks using discrete particle swarm optimization (DPSOWCA)

In this paper, a novel weighted clustering algorithm in mobile ad hoc networks using discrete particle swarm optimization (DPSOWCA) is proposed. The proposed algorithm shows how discrete particle swarm optimization can be useful in enhancing the performance of clustering algorithms in mobile ad hoc networks. Consequently, it results in the minimum number of clusters and hence minimum cluster heads. The goals of the algorithm are to minimize the number of cluster heads, to enhance network stability, to maximize network lifetime, and to achieve good end‐to‐end performance. Analysis and simulation of the algorithm have been implemented and the validity of the algorithm has been proved. Results show that the proposed algorithm performs better than the existing weight‐based clustering algorithm and adapts to different kinds of network conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

Energy Efficient Clustering Scheme (EECS) for Wireless Sensor Network with Mobile Sink

The participants in the Wireless Sensor Network (WSN) are highly resource constraint in nature. The clustering approach in the WSN supports a large-scale monitoring with ease to the user. The node near the sink depletes the energy, forming energy holes in the network. The mobility of the sink creates a major challenge in reliable and energy efficient data communication towards the sink. Hence, a new energy efficient routing protocol is needed to serve the use of networks with a mobile sink. The primary objective of the proposed work is to enhance the lifetime of the network and to increase the packet delivered to mobile sink in the network. The residual energy of the node, distance, and the data overhead are taken into account for selection of cluster head in this proposed Energy Efficient Clustering Scheme (EECS). The waiting time of the mobile sink is estimated. Based on the mobility model, the role of the sensor node is realized as finite state machine and the state transition is realized through Markov model. The proposed EECS algorithm is also been compared with Modified-Low Energy Adaptive Clustering Hierarchy (MOD-LEACH) and Gateway-based Energy-Aware multi-hop Routing protocol algorithms (M-GEAR). The proposed EECS algorithm outperforms the MOD-LEACH algorithm by 1.78 times in terms of lifetime and 1.103 times in terms of throughput. The EECS algorithm promotes unequal clustering by avoiding the energy hole and the HOT SPOT issues.     

Topology and mobility considerations in mobile ad hoc networks

A highly dynamic topology is a distinguishing feature and challenge of a mobile ad hoc network. Links between nodes are created and broken, as the nodes move within the network. This node mobility affects not only the source and/or destination, as in a conventional wireless network, but also intermediate nodes, due to the network’s multihop nature. The resulting routes can be extremely volatile, making successful ad hoc routing dependent on efficiently reacting to these topology changes.

In order to better understand this environment, a number of characteristics have been studied concerning the links and routes that make up an ad hoc network. Several network parameters are examined, including number of nodes, network dimensions, and radio transmission range, as well as mobility parameters for maximum speed and wait times. In addition to suggesting guidelines for the evaluation of ad hoc networks, the results reveal several properties that should be considered in the design and optimization of MANET protocols.     

An energy aware algorithm for OLSR clustering

One of the important aspects of a mobile ad hoc network (MANET) is the limitation of the amount of available energy and the network lifetime. The tremendous amount of using mobile nodes in wireless communication medium makes energy efficiency a fundamental requirement for MANETs. In this paper, we propose a novel energy aware clustering algorithm for the optimized link state routing (OLSR) routing protocol. This algorithm takes into account the node density and mobility and gives major improvements regarding the number of elected cluster heads. Our objective is to elect a reasonable number of cluster heads that will serve for hierarchical routing based on OLSR. The proposed algorithm aims to increase the network lifetime by considering the ad hoc residual energy while taking routing decisions. It also optimizes the delay of carried flows by adopting a selective forwarding approach based on a hierarchical routing model.     

HEED: a hybrid, energy-efficient, distributed clustering approach for ad hoc sensor networks

Topology control in a sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering sensor nodes is an effective topology control approach. We propose a novel distributed clustering approach for long-lived ad hoc sensor networks. Our proposed approach does not make any assumptions about the presence of infrastructure or about node capabilities, other than the availability of multiple power levels in sensor nodes. We present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of the node residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. HEED terminates in O(1) iterations, incurs low message overhead, and achieves fairly uniform cluster head distribution across the network. We prove that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks. Simulation results demonstrate that our proposed approach is effective in prolonging the network lifetime and supporting scalable data aggregation.     

A mobility-based framework for adaptive clustering in wireless adhoc networks

This paper presents a novel framework for dynamically organizing mobile nodes in wireless ad hoc networks into clusters in which the probability of path availability can be bounded. The purpose of the (α, t) cluster is to help minimize the far-reaching effects of topological changes while balancing the need to support more optimal routing. A mobility model for ad hoc networks is developed and is used to derive expressions for the probability of path availability as a function of time. It is shown how this model provides the basis for dynamically grouping nodes into clusters using an efficient distributed clustering algorithm. Since the criteria for cluster organization depends directly upon path availability, the structure of the cluster topology is adaptive with respect to node mobility. Consequently, this framework supports an adaptive hybrid routing architecture that can be more responsive and effective when mobility rates are low and more efficient when mobility rates are high     

Layerless Design of A Power-efficient Clustering Algorithm for Wireless Ad Hoc Networks under Fading

Traditional wireless ad hoc network power-efficient design proceeds separately on access and clustering algorithms by assuming perfect distance (that is, no fading and channel impairments) at most. In this paper, we discard the traditional layer-concept to tackle this important power-efficient wireless ad hoc networks under shadow fading, by identifying distance between a node pair as a sort of random distance to accommodate fading effect, which of course can be considered as a cross-layer design from traditional concept. By deriving the probability distribution of the distance between two nodes and the probability distribution of the distances between nodes and a randomly selected common reference node, the impacts of shadow fading on the link connectivity and node degree of the randomly constructed network topology are studied. Next, we propose a critical node first (CNF) based clustering algorithm to organize such a shadow faded random network topology into a power-efficient network architecture. By taking the shadow fading effects into considerations, our results show that the cluster-based network architecture generated by the proposed CNF-based clustering algorithm is power-efficient since the required number of exchanges of the cluster maintenance overheads is reduced.     

An Improved Weighted Clustering Algorithm in MANET

The original clustering algorithms in Mobile Ad hoc Network(MANET)are firstly analyzed in this paper.Based on which,an Improved Weighted Clustering Algorithm(IWCA)is proposed.Then,the principle and steps of ouralgorithm are explained in detail,and a comparison is made between the original algorithms and our improved method inthe aspects of average cluster number,topology stability,clusterhead load balance and network lifetime.The experimentalresults show that our improved algorithm has the best performance on average.