基于能量优化的认知无线电网络组播路由协议

针对认知无线电网络节点动态频谱分配的特点,利用静态博弈方法,根据次用户占用频谱越宽所造成干扰越大,建立基于价格惩罚机制的古诺模型解决频谱分配问题,通过求解纳什均衡,频谱利用率达到最优。根据最小增量按需驱动思想建立了节约能量的组播树,提出基于能量优化的适用于认知无线电网络的按需组播路由协议。     

An energy-efficient permutation routing protocol for single-hop radio networks

A radio network (RN) is a distributed system where each station or node is a small hand-held commodity device called a station. Typically, each station has access to a few channels for transmitting and receiving messages. By RN(p, k), we denote a radio network with p stations, where each station has access to k channels. In a single-hop RN, every station is within the transmission range of every other station. Each station consumes power while transmitting or receiving a message, even when it receives a message that is not destined for it. It is extremely important that the stations consume power only when it is necessary since it is not possible to recharge batteries when the stations are on a mission. We are interested in designing an energy-efficient protocol for permutation routing, which is one of the most fundamental problems in any distributed system. An instance of the permutation routing problem involves p stations of an RN, each storing n/p items. Each item has a unique destination address which is the identity of the destination station to which the item should be sent. The goal is to route all the items to their destinations while consuming as little energy as possible. We show that the permutation routing problem of n packets on an RN(p, k) can be solved in 2n/k+(p/k)/sup 2/+p+2k/sup 2/ slots and each station needs to be awake for at most 6n/p+2p/k+8k slots. When k/spl Lt/p/spl Lt/n, our protocol is more efficient, both in terms of total number of slots and the number of slots each station is awake compared to a previously published protocol by Nakano et al. (2001).     

Energy-efficient cooperative routing in BER constrained multishop networks

Due to the limited energy supplies of nodes, in many applications like wireless sensor networks energy-efficiency is crucial for extending the lifetime of these networks. We study the routing problem for multihop wireless ad hoc networks based on cooperative transmission. The source node wants to transmit messages to a single destination. Other nodes in the network may operate as relay nodes. In this paper, we propose a cooperative multihop routing for the purpose of power savings, constrained on a required bit error rate (BER) at the destination. We derive analytical results for line and grid network topologies. It is shown that energy savings of 100% are achievable in line and grid networks with a large number of nodes for BER = 10⁻⁴ constraint at the destination.     

无线传感器网络节能路由算法研究

通过对多种类型的无线传感器网络协议的研究,提出一种基于节点最佳路径移动的无线传感器网络节能路由算法(EEBM).它通过寻找瓶颈节点、冗余点以及选择最佳节点移动路径的方法,提高"瓶颈节点"的寿命,从而延长了整个网络的生命周期.仿真结果表明,EEBM算法比其他节点移动算法有较大的改进.     

多级能量异构传感器网络能量有效的路由算法

能量异构在无线传感器网络中普遍存在,由于多级能量异构无线传感器网络节点的初始能量在一定范围内随机分布,为了能有效地利用节点能量的异构性降低网络能耗、延长网络稳定周期,提出一种适用于能量异构环境的多级能量异构传感器网络能量有效的路由算法。节点根据其当前剩余能量与网络平均能量的比值决定其成为簇首的概率,通过调整节点的阈值,并基于此决定是否成为簇首,且在簇间采用多跳路由协议。仿真结果表明多级能量异构传感器网络能量有效的路由算法可以有效地均衡网络能量消耗,延长网络稳定周期。     

能量高效的无线传感器网络分簇路由协议

针对无线传感网中存在的节点能量受限,网络循环利用周期短,吞吐量少等问题,提出了一种能量高效的无线传感器网络分簇算法--KAF(K-means and FAH).算法初始阶段基于改进的K均值(K-means)聚类获得网络分簇;利用模糊层次综合评价(FAHP)方法,根据节点能量、距基站的距离、节点能量效率等因素优化簇首选择;在数据传输阶段,根据传输距离、能量、跳数等因素构建节点多跳路由方式,有效减少了节点在数据传输时的能量消耗.仿真实验表明:相比于LEACH-K,KPSO等其他分簇路由协议,KAF对减少节点能耗,延长网络生命周期,增加网络吞吐量等方面均有明显改进.     

节能高效的无线传感器网络非均匀分簇路由协议

为了有效均衡无线传感器网络能耗、缓解能量洞问题、延长网络生命周期,提出了一种节能高效的非均匀分簇路由协议,其核心思想是采用结合计时广播和簇头轮换机制的非均匀分簇（BR—EEUC）算法对网络分簇,并根据代价函数选择代价较低的簇头作为中继节点,形成以汇聚节点为根节点的多跳路由,从而大大降低了能量开销。通过在OMNet＋＋平台上的仿真实验结果表明：与LEACH和EEUC等路由协议相比,该协议有效地均衡了网络能量消耗,延长了网络寿命。     

A unified framework for off-line permutation routing in parallel networks

In this paper we present a general strategy for finding efficient permutation routes in parallel networks. Among the popular parallel networks to which the strategy applies are mesh networks, hypercube networks, hypercube-derivative networks, ring networks, and star networks. The routes produced are generally congestion-free and take a number of routing steps that is within a small constant factor of the diameter of the network. Our basic strategy is derived from an algorithm that finds (in polynomial time) efficient permutation routes for aproduct network, G×H, given efficient permutation routes forG andH. We investigate the use of this algorithm for routingmultiple permutations and extend its applicability to a wide class of graphs, including several families ofCayley graphs. Finally, we show that our approach can be used to find efficient permutation routes among the remaining live nodes infaulty networks.This research was supported in part by a grant from the NSF, Grant No. CCR-88-12567.     

Energy-efficient routing over coordinated sleep scheduling in wireless ad hoc networks

In this paper, we study how energy-efficient routing at the network layer can be coordinated with sleep scheduling at the link layer to increase network-wide energy efficiency in wireless ad hoc networks. We identify a trade-off between the reduced transmit power at senders with multi-receiver diversity and the increased receive power at forwarders with coordinated sleep scheduling. Moreover, we provide a comprehensive study of how coordinated sleep scheduling affects the energy-efficient routing performance based on a 2-D gird topology and time division multiple access (TDMA) medium access control (MAC). Simulation results demonstrate the effectiveness of the integrated routing and sleep scheduling, significant impact of coordinated sleep scheduling on the energy-efficient routing performance, and relationship between networking conditions (in terms of the traffic load and node density) and overall system performance achieved by different energy-efficient routing protocols.     

Energy-efficient routing for mobile data collectors in wireless sensor networks with obstacles

This paper proposes an energy-efficient routing mechanism by introducing intentional mobility to wireless sensor networks (WSNs) with obstacles. In the sensing field, Mobile Data Collectors (MDCs) can freely move for collecting data from sensors. An MDC begins its periodical movement from the base station and finally returns and transports the data to the base station. In physical environments, the sensing field may contain various obstacles. A research challenge is how to find an obstacle-avoiding shortest tour for the MDC. Firstly, we obtain the same size grid cells by dividing the network region. Secondly, according to the line sweep technique, the spanning graph is easily constructed. The spanning graph composed of some grid cells usually includes the shortest search path for the MDC. Then, based on the spanning graph, we can construct a complete graph by Warshall-Floyd algorithm. Finally, we present a heuristic tour-planning algorithm on the basis of the complete graph. Through simulation, the validity of our method is verified. This paper contributes in providing an energy-efficient routing mechanism for the WSNs with obstacles.     

User social activity-based routing for cognitive radio networks

The social activities of Primary Users (PUs) and Secondary Users (SUs) affect actual accessible whitespace in Cognitive Radio Networks (CRNs). However, the impacts of primary activities on available whitespace have been extensively investigated due to the dominating priority of PUs, while the impacts of secondary activities on actual accessible whitespace have been ignored. Therefore, we propose to incorporate the primary and secondary activities in the analysis and decision of the accessible whitespace, namely, both the dominance of PUs over SUs and the competitions among SUs are simultaneously taken into account. Specifically, we first approximate primary activity probability based on the real datasets of mobile phone usage records, then the spectrum opportunity between a pair of communication SUs is deduced based on primary activities. Next, we infer the access probability limit of SUs successfully accessing the whitespace according to the primary activity probability, and depict the secondary activity probability from the views of social activity patterns and social networks respectively. Furthermore, the actual accessible probability of whitespace is given by introducing the competitions among SUs. Finally, a greedy routing algorithm, considering the accessible whitespace and the distance to the destination, is proposed to verify our idea. The experiment results based on the real datasets demonstrate the correctness of our analysis and the advantages of the proposed algorithm.     

基于稳定性的认知Ad Hoc网络路由协议

针对认知无线电Ad Hoc网络中各个节点可用频谱的多样性、时变性和差异性的问题,传统路由协议不能适用于认知无线电Ad Hoe网络,提出了一种基于稳定性的路由协议.该协议综合考虑认知无线电Ad Hoc网络特性,通过计算每个节点的稳定性并引入分集传输,进行传输模式选择和信道选择,利用包括路径稳定性、路径跳数、路径信道切换次数的路由尺度进行路径选择.仿真分析表明,该协议能减少路径信道切换次数,提高路径稳定性和路径建立成功概率.     

Self adaptive routing for dynamic spectrum access in cognitive radio networks

Cognitive radio technology inherently possesses self adaptivity. In order to design self adaptive mobile cognitive radio networks, routing is one of the key challenging issues to be addressed. In this paper, a novel self adaptive routing (SAR) algorithm for multi-hop cognitive radio ad hoc networks is proposed. The proposed routing algorithm incorporates with routing metrics and autonomous distributed adaptive transmission range control mechanism to provide self adaptivity. SAR aims to choose optimal routes at the outset of routing and aims to retain optimal route by the use of route adaptation and route preservation. SAR is compared with previously suggested algorithms to indicate performance differences. Extensive experimental evaluations are performed in the ns2 simulator. It is shown that the SAR provides better adaptability to the environment than the previously suggested algorithms and maximizes throughput, minimizes end-to-end delay in a number of realistic scenarios and significantly improves routing performance.     

Hot-potato algorithms for permutation routing

We develop a methodology for the design of hot-potato algorithms for routing permutations. The basic idea is to convert existing store-and-forward routing algorithms to hot-potato algorithms. Using it, we obtain the following complexity bounds for permutation routing: n×n Mesh: 7n+o(n) steps; 2ⁿ hypercube: O(n²) steps; n×n Torus: 4n+o(n) steps. The algorithm for the two-dimensional grid is the first to be both deterministic and asymptotically optimal. The algorithm for the 2ⁿ-nodes Boolean cube is the first deterministic algorithm that achieves a complexity of o(2ⁿ) steps     

Probabilistic quality-aware routing in cognitive radio networks under dynamically varying spectrum opportunities

In this paper, we introduce a probabilistic routing metric that considers the peculiar characteristics of the operating environment of cognitive radio networks (CRNs). This metric captures the dynamic changes in channel availabilities due to the randomness of primary user’s activity and the rich channel diversity due to the fact that a CRN is expected to operate over highly separated frequency channels with different propagation characteristics. Our metric, Probability of Success (PoS), statistically quantifies the chances of a successful cognitive radio (CR) packet transmission over a given channel. Based on the PoS metric, we propose a joint probabilistic routing and channel assignment protocol for multi-hop CRNs that attempts at selecting the path with the maximum probability of success among all possible paths for a given CR source-destination pair. Selecting such a path results in minimizing the number of disruptions to CR packet transmissions, which consequently improves network throughput. Simulation results verify the significant throughput improvement achieved by our protocol compared to reference CRN routing protocols.     

Search: A routing protocol for mobile cognitive radio ad-hoc networks

Recent research in the emerging field of cognitive radio (CR) has mainly focussed on spectrum sensing and sharing, that allow an opportunistic use of the vacant portions of the licensed frequency bands by the CR users. Efficiently leveraging this node level channel information in order to provide timely end-to-end delivery over the network is a key concern for CR based routing protocols. In addition, the primary users (PUs) of the licensed band affect the channels to varying extents, depending on the proportion of the transmission power that gets leaked into the adjacent channels. This also affects the geographical region, in which, the channel is rendered unusable for the CR users. In this paper, a geographic forwarding based SpEctrum Aware Routing protocol for Cognitive ad-Hoc networks (SEARCH), is proposed that (i) jointly undertakes path and channel selection to avoid regions of PU activity during route formation, (ii) adapts to the newly discovered and lost spectrum opportunity during route operation, and (iii) considers various cases of node mobility in a distributed environment by predictive Kalman filtering. Specifically, the optimal paths found by geographic forwarding on each channel are combined at the destination with an aim to minimize the hop count. By binding the route to regions found free of PU activity, rather than particular CR users, the effect of the PU activity is mitigated. To the best of our knowledge, SEARCH takes the first steps towards a completely decentralized, CR routing protocol for mobile ad-hoc networks and our approach is thoroughly evaluated through analytical formulations and simulation study.