Recently, there is a huge attention that given to the field of service discovery protocols in vehicular networks (SDPs). In the research community, there are a lot of (SDPs) that were designed for wired networks, mobile ad hoc networks and mesh networks. In addition, few studies have been conducted in service discovery protocols for vehicular ad hoc networks (VANETs). Therefore, this paper review the related works in this filed and provides the main design issues that should be considered when designing such protocols. This paper also propose a Bus-based WSMP (WAVE Short Messages) dissemination approach. To implement this approach a realistic mobility model is built using bi-directional coupled technique. The performance Bus-based proposed model is evaluated in order to design an efficient algorithm for service discovery protocol that utilizes the public bus networks. The results of the realistic simulation model are compared with mathematical framework. It is shown that the bus outperforms other vehicles in beacon delivering ratio. Therefore, the idea of using public buses in addition to the beaconing approach can be used in future work for designing efficient algorithms in the field of vehicular networks.

Summary Chinese Digital Bibliography & Library Project (C‐DBLP) is a huge and real‐life co‐author social network in China, rarely cited by published paper. It contains a large amount of ground‐truth community structure with distinguished research topics. Despite the fact that rich studies on community detection have been conducted with gains of practically fruitful algorithms, unfortunately, with the coming of ‘Big Data’ era and speedy development of mobile devices, social networks like C‐DBLP have incredibly expanded on nodes and edges, as a result, because of massive data cardinality, a large portion of community detection methods consume memory resource excessively. Therefore, in this work, we select Based on Structural Connection Hierarchical Exploration (BSCHE) algorithm to partition nodes in C‐DBLP because of its O(n) time cost, fast enough to process massive data, and its novel physical meaning of similarity between nodes defined by structural connection and availability. In addition, in order to avoid huge memory resource consumption caused by ‘Big Data’ of C‐DBLP, we strengthen BSCHE as a framework (BSCHEF) by our proposed ‘count‐pointer‐strategy’ imitated from incremental batch process to detect co‐author communities on C‐DBLP. The experiment results show that BSCHEF can find sets of communities onC‐DBLPmore effectively with the highest modularity value and the least execution time compared to other clustering algorithm. Copyright © 2015 John Wiley & Sons, Ltd.

Some new classes of Hamming metric Gray codes over Zpn, where p is a prime and n is an integer power of 2, are described; then, how these Gray codes can be used to generate the maximum number of edge-disjoint Hamiltonian cycles in an n-dimensional generalized hypercube (GHC), Qpn, is shown. For Qpn, the number of edge-disjoint Hamiltonian cycles generated using these methods is n(p -1)/2 which is the maximum possible since the degree of each node in Qpnis n(p - 1). In addition, for any integers p and n, p not necessarily a prime and n not necessarily a power of 2, how to generate the maximum number of edge-disjoint Hamiltonian cycles in Qnp is also described.

In this paper, we investigate the problem of achieving proportional fairness via access point (AP) association in multirate WLANs. This problem is formulated as a nonlinear programming with an objective function of maximizing the total user bandwidth utilities in the whole network. Such a formulation jointly considers fairness and AP selection. We first propose a centralized algorithm Non-Linear Approximation Optimization for Proportional Fairness (NLAO-PF) to derive the user-AP association via relaxation. Since the relaxation may cause a large integrality gap, a compensation function is introduced to ensure that our algorithm can achieve at least half of the optimal in the worst case. This algorithm is assumed to be adopted periodically for resource management. To handle the case of dynamic user membership, we propose a distributed heuristic Best Performance First (BPF) based on a novel performance revenue function, which provides an AP selection criterion for newcomers. When an existing user leaves the network, the transmission times of other users associated with the same AP can be redistributed easily based on NLAO-PF. Extensive simulation study has been performed to validate our design and to compare the performance of our algorithms to those of the state of the art.

Future Wireless Sensor Networks (WSNs) will be composed of a large number of densely deployed sensors. A key feature of such networks is that their nodes are untethered and unattended. Distributed techniques are expected in WSNs. Connected Dominating Sets (CDSs) have been widely used for virtual backbone construction in WSNs to control topology, facilitate routing, and extend network lifetime. This paper proposes a new distributed algorithm for CDS construction in WSNs. The algorithm represents an extension for our previously proposed centralized algorithm. The algorithm is intended to construct a CDS with the smallest ratio when compared to its centralized version. Simulation shows that our distributed approach has a maximum ratio of 1.53 to the centralized approach in term of CDS size, and it satisfies all of the geometrical properties of its canalized version. Based on this ratio, this distributed algorithm has an approximation factor of 7.65 to the optimal CDS. This approximation outperforms the existing distributed CDS construction algorithms.

A mobile ad hoc network is a collection of wireless mobile devices communicating with each other and forming a temporary network, without any pre-deployed infrastructure. Security in MANET is a main and important element for the basic functions of a network. One of the security technologies is intrusion detection system which provides a second line of defense. In this paper, we propose an efficient defense system based on a cooperative scheme to deal with intrusions in clustered ad hoc networks. Our proposed system provides security against all network attacks that can be detected by any node in the network, in particular detects the actor. It is simple, reliable, effective and its performance not affected by status of channel.

Sandstorms are serious natural disasters, which are commonly seen in the Middle East, Northern Africa, and Northern China.In these regions, sandstorms have caused massive damages to the natural environment, national economy, and human health. To avoid such damages, it is necessary to effectively monitor the origin and development of sandstorms. To this end, wireless sensor networks (WSNs) can be deployed in the regions where sandstorms generally originate so that sensor nodes can collaboratively perform sandstorm monitoring and rapidly convey the observations to remote administration center. Despite the potential advantages, the deployment of WSNs in the vicinity of sandstorms faces many unique challenges, such as the temporally buried sensors and increased path loss during sandstorms. Consequently, the WSNs may experience frequent disconnections during the sandstorms. This further leads to dynamically changing topology. In this paper, a topology analysis of the WSNs for sandstorm monitoring is performed. Four types of channels a sensor can utilize during sandstorms are analyzed, which include air-to-air channel, air-to-sand channel, sand-to-air channel, and sand-to-sand channel. Based on the channel model solutions, a percolation-based connectivity analysis is performed. It is shown that if the sensors are buried in low depth, allowing sensor to use multiple types of channels improves network connectivity. Accordingly, much smaller sensor density is required compared to the case, where only terrestrial air channels are used. Through this topology analysis a WSN architecture can be deployed for very efficient sandstorm monitoring.

In this paper, we consider how to achieve proportional fairness in multi-rate 802.11 WLANs by investigating an integrated problem of power control and AP Association in order to provide an effective tradeoff between network throughput and fairness. Since jointly considering power control and AP association for proportional fairness is NP-hard, we propose a centralized heuristic approach. By introducing a new concept of AP utility, we establish the relationship between the network utility and the AP utility according to proportional fairness. This relationship is exploited to design an algorithm PCAP to optimize the network utility by increasing the average and decreasing the variance of the AP utility. Extensive simulation study is performed and the results demonstrate that PCAP yields a significant improvement in terms of throughput, fairness, and power consumption compared to other popular power control algorithms.

We investigate the dynamic connectivity of cognitive radio ad-hoc networks (secondary networks) coexisting with licensed networks (primary networks) that experience time-varying on-off links. It is shown that there exists a critical density λs*such that if the density of secondary networks is larger than λs*, the secondary network percolates at all time t >; 0, i.e., there exists always an infinite connected component in the secondary network under the time- varying spectrum availability. Furthermore, the upper and lower bounds of λs*are derived and it is shown that they do not depend on the random locations of primary and secondary users, but only on the network parameters, such as active/inactive probability of primary users, transmission range, and the user density.

On-demand routing protocols used in mobile ad hoc networks suffer from transmitting a huge number of control packets which increases the overhead. In this new algorithm (ERDA), we try to improve the route discovery algorithm by reducing the routing overhead in the presence of random traffic. ERDA broadcasts any route request travelling within their source node's neighbourhood region according to the routing algorithm used. However, propagation of the route request is deliberately delayed outside this region to provide the associated chase packet with an opportunity to stop the fulfilled route request and minimise network congestion. The algorithm is adaptive and continuously updates the boundary of each source node's neighbourhood to improve performance. We provide detailed performance evaluation using simulation modelling. Our result shows that ERDA improves the performance by minimizing the average end-to-end delay as well as the network overhead and congestion level.