Applied Mechanics and Materials Vols. 385-386

Abstract: Security is critically important for hierarchical wireless sensor networks. Due to the limited resources of the sensor nodes, the traditional key management schemes are not suitable for wireless sensor network. In this paper, a new key management scheme for hierarchical wireless sensor network is proposed, which would be effectively against cluster node capture by supporting multiple keying mechanisms. The security of network is independent on a single key. Compared with the LEAP protocol, our scheme has lower consumption and higher scalability.

Abstract: A best partner selection strategy is proposed in cooperative network coding systems. In the strategy, the cooperated partner set is determined by the basic demand that the partners can decode correctly each other. Then, the best partner is selected from the set, which has the best channel gain among the set. Outage probability is also analyzed, and numerical results show that the proposed scheme can reduce outage probability of cooperative network coding systems effectively.

Abstract: The relay node placement in wireless sensor networks is usually constrained by physical factors, while most of present relay node placement approaches are unconstrained. To solve the problem, the paper presents a constrained relay node placement algorithm. Based on grid routing mechanism, the algorithm determines the grid intersections as candidates for the relay node locations, and places as fewer relay nodes as possible to assure the network connectivity. Consideration must be given to both the number of relay nodes and energy efficient, the paper uses the greedy norm and constrains to place relay nodes. By the analysis and study of the experiments, the performance of the proposed algorithm is more superior to the algorithm without constrains.

Abstract: Before the channel allocation of wireless networks, usually need to select the appropriate channel conflict model to model the channel collision. For the current channel conflict model cant model the channel collision comprehensively, the graph N-tuple coloring model based on graph N-tuple coloring theory is proposed in this article. The theoretical analysis and simulation results show that this model can model the channel collision comprehensively, and transform the channel allocation problem into N-tuple coloring problem on a graph for the further analysis and solve.

Abstract: As one of VHF data links of ATN, VDL2 is publicly recognized as the next generation data-link in the transition period. The paper focused in the performance research of MAC, of which p-CSMA is the core protocol, based on network simulation. As the precondition of simulation, we build VDL2 model in an integral way and realize MAC process modules in both ground station side and aircraft side applying dynamic process and queue management mechanism. In the paper, Performance targets are defined to evaluate the system performance. Through simulation, trends between parameters and targets are reached and the relationships are revealed between packet delay and throughput\ packets strength.

Abstract: SSL protocol is widely used in network security, such as Internet user account, electronic exchange data, etc. The SSLStrip MITM attack exist the problem of processing performance and intrusion detection. Based on the idea of network Phishing, the SSL MITM attack with the DNS spoofing resolved the above mentioned problems. The security of SSL login in daily Internet services was also analyzed, and the improvement and suggestion were provided.

Abstract: This paper mainly focus on the modeling and simulating of WLAN (the wireless local area network) IEEE802.11. Based on the current research of IEEE 802.11 protocol and the most powerful network simulation tool OPNET, the paper introduces various behavior of WLAN and standards for WLAN. Research on CSMA / CA(Carrier Sense Multiple Access / Collision Avoidance) and a simulation study of optimization algorithm to the binary backoff time are conducted, DCF(Distributed Coordination Function)-based access solutions are analyze. The simulation of MAC(media access control) and PHY(Physical Layer）functional design and algorithm theory have been carried out. It can be seen from the simulation result that the theory of optimal design reduces network latency and packet loss rate, and improve the system throughput, which has an important reference value for the future deployment of WLAN IEEE 802.11 standards.

Abstract: The submitting of OPC (OLE for Process Control) has promoted the progress of the data collection in process control and industrial automation, and formulated the industry standard for the process real-time data exchange. Aiming at the key problem of ensuring the use of application program as OPC client to link multi-remote OPC server and real-time collect process data in control system, OPC technology and the connection and access technology of multi-remote OPC server were introduced and analyzed in detail. This method has been successfully applied to develop the DCS I/O communication and control loop error test software, and provided better performance.

Abstract: Aiming at the problem of tag conflict in the RFID system, an improved algorithm based on dynamic framed slotted ALOHA algorithm is proposed. In this algorithm , when the recognition of a frame length is still not finished, according to the existing conflict timeslot and free timeslot inside of frame, frame length can adjusted in advance, furthermore a new frames recognition process is began, which can improve the recognition efficiency of the existing algorithm, increase throughput. The performance simulation experiment shows that the improved algorithm has more advantage than dynamic slotted ALOHA algorithm.

Abstract: The information hiding is a technology of hiding the message that you want to send into the multimedia carrier signals secretly, realizes hidden communication or identification ultimately. XML is the format of information exchange on the Internet. It has received a wide range of applications and supports once be proposed. In this paper, several text information hiding methods are analyzed based on the structures and characteristics of the XML documents. At last, the paper realizes the information hidden by applies to the method of changing the mark letter case.