Single Beacon Cruise Positioning Algorithm in Wireless Sensor Networks

Node localization is important in WSNs （Wireless sensor networks） applications. We present a new cruise positioning algorithm, where a single beacon node cruises an entire network, broadcasting its position periodically with fixed signal strength. Meawhile, an unknown node obtains the location and the corresponding distance of the beacon node. Two possible position coordinate sets for the unknown node can then be calculated, and the coordinate mean of the point set with a small variance is an unbiased estimator of the unknown node＇s coordinate. The positioning algorithm＇s computation is simple, positioning accuracy is not limited by a physical distance measuring tool, and there are no restrictions on the path of motion, which makes it more realistic. An algorithm simulation is presented to compare the original and cruise location algorithm. Numerical results show that the cruise localization algorithm can achieve good positioning accuracy.     

Dynamic Collaborative Support Vector Machine for Target Classification in Wireless Sensor Networks

Target classification is a significant topic addressed in Wireless sensor networks （WSNs）. The distributed learning for target classification is desired for highly-constrained WSN since the processing ability, energy and bandwidth are strictly limited. This paper presents a dynamic data fusion based collaborative Support vector machine （SVM） for target classification in WSN. With the collaboration of multiple sensor nodes, the dynamic collaborative SVM can independently select the optimal set of sensor nodes according to the estimated energy consumption and information contribution. Then the training process of SVM is incrementally carried out in the dynamic data fusion framework with the consideration of tradeoff between energy consumption and information contribution. Because of the purposeful sensor nodes selection strategy, the dynamic collaborative SVM can conquer the inevitable missing rate and false rate of samples in WSN and save the energy for prolonging the lifetime of WSN. Furthermore, the dynamic collaborative SVM can also improve the robustness in target classification, and achieve the tradeoff between the performance and the cost. The experimental results demonstrate that the proposed dynamic collaborative SVM can effectively implement target classification in WSN. It is also verified that the proposed dynamic collaborative SVM has outstanding performance in energy efficiency and time delay.     

A Key Pre-distribution Scheme for Wireless Sensor Networks Using Hexagonal Deployment knowledge

To insure security for the messages sent among sensor nodes, it is important to establish keys for encryption to nodes which have had no prior direct contact with each other in wireless sensor networks. To solve the problem above, several key pre-distribution schemes have been proposed. In this paper, we present a novel key pre-distribution scheme using hexagonal deployment knowledge, in which the q-composite keys scheme has been improved. By using hexagonal division over the deploy- ment region, the probability of sharing common keys be- tween each sub-region and its neighboring sub-regions are equal, so the keys for encryption can be generated efficiently. The analytic results show that the scheme we pre-sented can achieve a higher connection probability of any two neighboring nodes than previous schemes, and net- work resilience against node capture can be substantially improved.     

Opportunistic Data Aggregation in Low-Duty-Cycle Wireless Sensor Networks with Unreliable Links

This paper proposes an opportunistic data aggregation algorithm to support the data collection in low-duty-cycle Wireless sensor networks （WSNs） with unreliable links. In this algorithm, each sensor selectively waits for some certain time to maximize the number of packets that it can aggregate from its downstream nodes, then transmits the aggregated result to an adaptively selected upstream node following an optimal forwarding sequence. Simulation results show that the algorithm can significantly increase the data aggregation efficiency, and reduce energy consumption and message overhead.     

An Effective Gated Scheduling with Pre-defined QoS Cross-layer Design for Wireless Networks

The proposed M-gated scheduling algorithm rules the server in wireless networks stays with a station for at most M times gated services. By the method of embedded Markov chain and probability generating function we developed a model with vacations and acquired the theoretical value of average queue length and packet delay. Like E-limlted scheduling algorithm, its performance is close to that of the optimal polling scheme, exhaustive scheduling, but the inherent unfairness problem for the latter is avoided. And it also does not require the server to know the status of stations, queues information. Compared with E-limited, M-gated has less jitter and is more robust. We then use the derived quality of service parameter as the basis for cross-layer design. Simulations results show the network is more stable and can keep the queue length and the packets delay under QoS level. When putting E- limited and M-gated scheduling in the same cross-layer design scheme, the latter has less overhead especially when the system is heavily loaded.     

PFQ-OS： A Packet Fair Queueing Based Opportunistic Scheduler in Wireless Networks

In this paper, we investigate the issues of extending the Packet fair queueing （PFQ） algorithms into continuous channel model. We present a PFQ-based Opportunistic scheduler （PFQ-OS）, which can improve user throughput while satisfying strict short-term fairness. We decouple the conflicting design objectives of fairness and user throughput improvement by introducing a Search radius （SR） into the framework of PFQ. We develop an analytical model and derive the fairness properties of PFQ-OS, which are related to the SR. Thereby system operators can focus on opportunistic scheduling for the users within the SR without violating the fairness guarantee. We further investigate the designing of scheduling policy under the strict fairness constraints, and propose that in order to utilize the opportunistic scheduling all the time, the selection rule should provide all the users with equal chance in being scheduled at each selection. Accordingly, we present Maximum relative SNR （Max-rSNR） selection rule for PFQ-OS. We derive the bounds in terms of user throughput under Rayleigh fading channel. An extensive set of simulations testifies our derived theoretical properties that PFQ-OS can significantly improve user throughput while providing excellent short-term fairness guarantee.     

CL-TAP： An Efficient Certificateless Based Trusted Access Protocol for WLAN

Based on the certificateless public key cryptography and the trusted computing technologies~ a certificateless based trusted access protocol for WLAN （Wireless local area networks） is proposed. Such proto- col realizes the mutual authentication and unicast session key agreement between STA and AP within 3 protocol rounds. In particular, the platform authentication and in- tegrity verification are achieved during the authentication procedure. The security properties of the new protocol are examined using the Extended Canetti-Krawczyk secu- rity model. The analytic comparisons show that the new protocol is very ei~icient in both computing and communi- cations.     

Jitter Detection for Synchronization Control in Wireless Multimedia Sensor Networks

Collaborative in-network processing operations in Wireless multimedia sensor networks （WMSNs） often require effective synchronization control. Extensive researches in the traditional networks mainly focus on the synchronization control with the buffer management in the receiver. However, for WMSNs, the chaotic transport channel and low bandwidth introduce serious jitter. Jitter degrades the timing relationship among packets in a single media stream and between packets from different media streams and, hence, creates multimedia synchronization problems. Moreover, too much jitter will also degrade the performance of the streaming buffer. By only employing the buffer management scheme in the receiver, we can hardly satisfy the synchronization requirement of the in-network processing. In this study, we propose an active jitter detection mechanism for the synchronization control in WMSNs. This mechanism will improve the quality of service in multimedia networking by discarding the jitter-corrupted packets immediately and balancing the delay and jitter actively. We implement the proposed scheme in the practical WMSNs platform. The experiment results show that our scheme can reduce the average packet jitter effectively and improve the synchronization controlling performance significantly.     

An Intra-PAN Mobility Management Scheme for IPv6 over Low-Power Wireless Personal Area Networks

This paper proposes an intra-PAN mobility management scheme for IPv6 over Low-power wireless personal area networks （6LoWPAN） on the basis of ＂networkbased＂ idea. We developed a tree-like network architecture which includes coordinate nodes for packet routing. All of the control messages are designed to transmit in link layer, and the sensor nodes are free to consider care-of address and the mobile nodes are unnecessary to deal with any mobility handoff messages. The simulation results show that this scheme efficiently cuts down the signaling cost and reduces the energy consumed by fixed nodes which can extend the life time of the whole Personal area networks （PAN）.     

Relay Node Placement with Base Stations in Wireless Sensor Networks Fault-Tolerant

It has been proposed to deploy relay nodes for the sake of prolonging Wireless sensor networks （WSN） lifetime, such that sensors transmit the sensed data to them which in turn delivers the data to base stations. For survivability requirements, relay placements which considers fault tolerant ability have been noticed and studied. While related works are limited or most existing works don＇t take factors such as fault tolerance, or base stations into account comprehensively in two tired WSN. We focus on fault tolerant relay node placement in two-tiered het- erogeneous WSN with base stations. As far as we know, fault tolerance contains two fundamental aspects, for one is multi-coverage and the second is multi-path. It is a NP- hard problem and figure out an approximation, whose approximation ratio is enhanced to be （18＋ε）. While a sub-problem approximation is also described as supplementary. Experimental results verify that the number of relay nodes deployed by our algorithm is somewhat superior to existed relay node placement solutions.     

Virtual Network Embedding Algorithm for Load Balance with Various Requests

Virtual network embedding （VNE） is a crucial technology for network virtualization to allocate network resource. Virtual network request in which node and link resource have great disparity will lead to unbal- anced resource distribution and lower acceptance ratio of virtual network requests. In this paper, we provide a vir- tual network embedding algorithm for load balance with various requests. It maps virtual nodes to substrate nodes of which node link residual resource ratio is closest to that of virtual nodes, and then maps the virtual link to physical path using shortest path first algorithm with the link node residual resource ratio constraint. Simulation shows that the provided algorithm can get higher acceptance ratio and network resource utilization for load balance.     

QoS Routing in Wireless Mesh Networks

An H-hop interference model is proposed, where the transmission is successfully received if no other nodes that are within H hops from the receiver are transmitting on the same channel simultaneously. Based on this model. the interference-free property in the Time division multiple access Wireless mesh networks is analyzed. A heuristic algorithm with max-rain time slots reservation strategy is developed to get the maximum bandwidth of a given path. And it is used in the bandwidth guaranteed routing protocol to find a path for a connection with bidirectional bandwidth requirement. Extensive simulations show that our routing protocol decreases the blocking ratios significantly compared with the shortest path routing.     

An Energy Balancing Adaptive Routing Strategy Based on Interference Model in 6LoWPANs

IPv6-enabled low-power wireless personal area network （6LoWPAN） is an important part of the Internet of Things which will drastically transform the way our society functions. Designing an efficient routing strategy is crucial for optimizing traffic over 6LoWPAN resources and extending the network lifetime. This paper proposes an energy balancing adaptive routing strategy named EBAR. Considering the dynamic traffic and constrained energy in 6LoWPAN, EBAR adaptively updates paths between different source-destination pairs and balances the energy in 6LoWPAN. Simulation results indicate that EBAR can promote network performance and balance the energy in the network.     

P-Zone： Connectivity-based Packet Path Tracing in Wireless Sensor Networks

In large-scale Wireless sensor networks （WSNs）, the network status is complex and unpredictable, which brings great challenges to practical network design and management. Tracing the route path of each data packet in the network is an important way to observe network behaviors and understand network dynamics. However, tracing the full route path of each packet could be highly challenging, due to the hard resource con- straint in WSNs. Our previous work proposes a hash-based path tracing mechanism, and leverages network connectivity and node locations to reduce the computational complexity. However, the node locations may be unavailable in some scenarios. In this work, we further propose a location-free enhancement to the hash-based path tracing mechanism, called P-Zone. P-Zone requires only network connectivity information to reduce the computational complexity. Theoretical analysis and practical simulations are conducted to evaluate the effectiveness and performance of our design. The results indicate that P-Zone can significantly reduce the computational complexity of the hashbased path tracing mechanism, while effectively tracing the full route path of each packet in the network in a real-time manner, and outperforms the state-of-the-art methods.     

A New Positioning Method for Location-Based Services in Wireless LANs

Positioning techniques are crucial to achieve location-based services. Location estimation systems using received signal strength in wireless LANs （Local area network） have attracted great attention for the advantages of low cost, ubiquitous coverage and ease of deployment. Existing methods neglect the difference between contributions of access points to location estimation results. Signals from far access points travel long distance and thus more uncertainty is added to the receive signal strength. This paper proposed a positioning method based on the Dempster-Shafer evidence theory. Different belief was assigned to signal strength from different access points according to its importance to location estimation. We carry out a series of experiments to evaluate the method and compare with other related work. Experimental results show that the approach gives a higher degree of positioning accuracy.     

Defending Against Sybil Attacks Based on Received Signal Strength in Wireless Sensor Networks

Sybil attacks is a particularly harmful attack against Wireless sensor networks （WSN）, in which a malicious node illegitimately claims multiple identities, and forges an unbounded number of identities to defeat redundancy mechanisms. This paper proposes using received signal strength of the nodes to defend against Sybil attacks when the Jakes channel was established. Aiming at improving the detection accuracy and reducing power consumption, we put forward the mutual supervision between head nodes and member nodes to detect Sybil attacks together, and compared the related detection scheme for Sybil attacks. The simulation results show that our scheme consumes lower power, and the detection accuracy is over 90%.     

TCP在无线链路上的性能问题

文章以无线LAN和蜂窝通信系统为例,首先回顾了无线链路的特征;然后概述了TCP/IP协议组用于无线链路时的性能问题,并为解决这些问题介绍了几种建议,验证了它们的优点和局限性;最后讨论了未来无线系统的发展方向,以及它们即将面临的与TCP性能有关的挑战.     

通用无线接入与中国的相应频率规划考虑

讨论了新世纪中的通用无线接入、包括无线Internet在未来全球个人通信中的地位与作用,进而论述中国的相应频率规划考虑。     

基于超宽带信道的无线通用串行总线测试与分析

无线通用串行总线系统被视为下一代无线个人局域网通信的关键技术之一,并且被基于多频带正交频分复用技术的超宽带公共无线电平台进行标准化.文中对无线通用串行总线系统在超宽带通信信道中进行性能测试,其中使用了4个超宽带信道模型,每个模型使用100个现实通信信道.实验表明,无线通用串行总线系统在室内多径传输环境下能实现低速200 Mb/s 10 m和高速480 Mb/s 4 m的传输性能,达到了高速无线个人局域网技术的要求.