Earticle

The traditional Gossip protocol selects the neighbor nodes randomly. It does not consider the factors, such as the capacities of network transmission and node storage, which affect the network performance. It further causes the drawback of successful search ratio relatively lower, and also network transmission payloads have the characteristics of randomness. In this paper, to overcome those drawbacks of traditional Gossip protocol, a neighbor node selection algorithm has been studied, and various factors that may affect the neighbor node selection have been analyzed in P2P networks. A new neighbor node selection policy has been proposed, which is a reliable Gossip message transmission Protocol based on fuzzy theory. Empirical simulation experiments with various data analysis have demonstrated the improvement of efficiency of the proposed strategy on node selection and correctness of the proposed algorithm in P2P networks.

Efficient communication is a major requirement in crisis situations. This research is motivated by the need to develop new communication tools to enhance the coordination and response time of first responders. In this paper we present an application which enables group calls among different rescue entities. Additionally, we present a video application that provides a real time access to surveillance cameras. The objective is to provide a powerful communication tool that can be used over different network technologies. As opposed to other existing systems, our application provides a complete communication platform that relies on open standards. A prototype has been implemented and tested during a demonstration held in July 2007 in Luxembourg. In this paper we provide technical details on how the applications were realized and evaluate the outcome of the demonstration. We also propose future improvements based on the outcome to enhance the system.

IEEE 802.15 working group established a new task group, body area network (TG-BAN), to develop short range wireless technology in and around human body recently. This paper investigates networking issues in implant communications at 2.4 GHz frequency band. The object is better understanding of medical implant networks and how and where to start TG-BAN work. We applied IEEE 802.15.4b and 802.15.4a-chirp spread spectrum (CSS) for implant communications. We derived a path loss model in the layered body and found two unique issues: clear channel assessment (CCA) of implant devices, interference from neighbor piconet in adjacent channel, and multihop long distance communication. All of them can be attributed to the rapid attenuation of electromagnetic wave through lossy tissue, which is about 30 dB more than the free space propagation. The carrier sense multiple access mechanism and transmit mask of 802.15.4b cannot be directly adopted. The modulation of 802.15.4a-CSS is robust to the interference from adjacent channel. A time division based MAC protocol should be considered by TG-BAN. Instead of routing among implant devices, a simple two-hop protocol which uses a body surface forwarder was presented and verified for long distance implant communications.

The performance of Wireless Sensor Networks (WSNs) is adversely affected by the radio irregularity and fading effect. Cooperation is introduced into WSNs and serves as an effective way to combat fading effects. Meanwhile, sensor nodes having heavier burden than others result in the energy imbalance problem which remains harmful to the system lifetime. In this paper, we design a protocol for cooperative WSNs with energy balance consideration. Since the design of WSNs is highly dependent on application scenarios, the effects of system parameters are thoroughly analyzed and a unified criterion is established to choose the proper cooperative scheme. Moreover, energy balance is achieved by adjusting the size of clusters. We classify energy consumption into two groups: inter-cluster energy consumption and intra-cluster energy consumption. Sensor nodes consuming higher energy in inter-cluster data communication form smaller clusters. Thus energy consumption is balanced between intra- and inter-cluster data communication. The proposed energy-balanced parameter-adaptable cooperative protocol (EBPACP) efficiently applies cooperation in cluster-based WSNs and balances energy consumption. A complete protocol design including the cluster formation, cooperative relationship buildup and data transmission are investigated thoroughly in this paper. Simulation results have shown that the proposed EBPACP provides good system performance in terms of energy efficiency and energy balance.

The large, rapidly growing field of wireless sensor networks (WSNs) offers the ability to collect and process massive amounts of information from various environments. This distributed data gathering and computation with the help of tiny, power-limited devices enables their use in surveillance, target detection and various other monitoring applications. In this context, the role of a sensor network can be viewed as that of a system that pays attention to a phenomenon of interest. Thus, the current body of literature on WSNs falls into two major categories: developing networks that a) pay attention to the environment to detect the phenomenon under consideration and b) improving the quality of attention paid by WSNs to these phenomena. In this paper, we summarize a theoretical framework for the context of attention in WSNs. This paper is the first step to develop a foundation for understanding the association between the nature of attention in WSNs and their real-world applications.