Abstract:To address the non-line-of-sight(NLOS) issue in the field of target location of wireless sensor network, a target location algorithm based on the disk of scatterers model in NLOS environment is proposed to mitigate the NLOS error. The new algorithm utilizes the weighted measurement mean value of the measurements of multipath time of arrives received by base stations and matches it to the theoritical mean value of the disk of scatterers model to establish the target function. Meanwhile, disk radius constraint is introduced to the target function. Through searching the extreme value of target function, an optimal solution contains the location of target can be obtained. Simulation experiments show that compared with other target location algorithms, the presented algorithm can obtain the global optimal solution and improve the positioning accuracy under NLOS environment.

Abstract:A Biclique cryptanalysis on lightweight block cipher MIBS-80 is presented in this paper. Exploiting two independent related-key difference trails, 4-round Biclique of dimension 4 is constructed and the key space is partitioned. To reduce the computational complexity, the precomputation and meet-in-the-middle technique is applied to sieve out the correct key for 12-round MIBS-80. The data complexity of this cryptanalysis is 2⁵² chosen plaintexts, the computational complexity is about 2^77.13 12-round MIBS-80 encryptions, the storage complexity is about 2^8.17, and the success probability is 1. Compared with the previous known cryptanalysis, the new method has advantages in the storage complexity and success probability.

Abstract:Routing protocols in wireless sensor networks tend to be designed for a particular task type and network status. The dynamic routing system can adaptively choose the optimal performance of routing protocols at run time. Based on policy engine, a dynamic routing system is designed for wireless sensor networks. This work uses a modular design approach which makes each sensor node to carry multiple routing protocols. Resources, such as neighbor table and output buffer, are shared between routing protocols. A routing protocol switching mechanism is implemented based on the policy engine. Experimental results show that, in multitasking network environments, dynamic routing can meet the quality of service while effectively reducing energy consumption.

Abstract:Mobile social network is a kind of opportunistic networks composed of a large number of nodes with social characteristic. However the prevalent community-based routing mostly chooses nodes that have optimal social characteristic to transmit messages, without considering the distribution of communities. Hense these algorithms usually result in high consumption of cyber resource and low transmission success when deployed directly in mobile social networks. To tackle these problems, this study proposes a community-based message opportunistic transmission algorithm(CMOT). For intra-community communication, CMOT chooses an optimal path for message transmission from local community to target community by comparing the transmission probability between the nodes. For inter-community messages transmission, CMOT chooses an optimal community path by comparing the community transmission probability. For intra-community in local community, messages are forwarded according to the encounter probability between nodes. The simulation results show that, compared with classical routing algorithms, such as PRoPHET, MaxProp, Spray and Wait, and CMTS, CMOT improves the successful message delivery ratio and evidently reduces network overhead.

Abstract:Activity recognition has broad application prospects in many fields including pervasive computing and human-computer interaction. In this paper, the technology of wireless-based activity recognition is introduced. By using wireless signals, one can achieve non-line-of-sight recognition without carrying any devices. Also, it is easy to deploy a wireless-based recognition system due to the ubiquity of wireless communication system. The basic idea is that, as a specific propagation path is formed when the signal is blocked, reflected or scattered at body, one can detect the different characteristics of propagation that correspond to the distinct human behaviors. As a result, action recognition is performed by analyzing the distinguishable features of signal propagation. The basic principles and applications of wireless-based activity recognition are reviewed, and the challenges and related performance metrics are presented. Finally, open problems are discussed to point out the future research trends.

Abstract:In this paper, set theory is introduced to the design of authenticated key agreement scheme for heterogeneous sensor networks, and a scheme based on bilinear dynamic accumulator is proposed. The previous schemes based on classical random graph and others mainly achieve key agreement between nodes, and separate authentication and key agreement. From the perspective of set theory, this work transforms authenticated key agreement into set element relationship certification, and integrates identity authentication and key agreement. It includes identity authentication, key agreement, and broadcast authentication. Sensors verify the identity of each other by exchanging ID and witnesses. Legitimate nodes generate a shared key. Broadcast messages are used to dynamically add/delete nodes, and update witness. Experimental results show that the new scheme not only achieves effective integration of authentication, key agreement and broadcast certification; but also has better security, scalability, and adaptive changes in the network structure. It is suitable for higher node performance and security requirements scenarios.

Abstract:Firstly, to solve the problem of threshold setting for step-counting in personal dead reckoning system, this paper proposes a self-learning of threshold based on FSM. It can obtain an adaptive threshold in a short period of time(about 10s), and improve the accuracy of pedometer algorithm. Secondly, the FSM splits the continuous gait into individuals, which are processed by PCA to obtain the step direction. In addition, the algorithm effectively solves the 180° ambiguity by analyzing the variation of forward acceleration. The results of the experiment show that the dynamic-window PCA decreases the amount of data to be processed by 61.2% and increases the accuracy by 11.1% compared to the fixed-window PCA.

Abstract:Message is delivered between nodes through single hop or multiple hops in wireless sensor networks(WSNs). Obtaining link quality information in advance which provides reference for the upper routing protocol to select link is the basis of delivering to the monitoring center accurately and in time. In this paper, a concrete analysis about the related works on WSNs link prediction based on intelligent learning is presented. A novel model, Cloud Model, is proposed to predict link quality. The large amounts of link quality samples are collected from different scenarios, and then adaptive gauss cloud transformation is applied to clustering training samples, such as RSSI, LQI, SNR and PRR. Taking the limit of node's resources into consideration, an Apriori algorithm is applied to mining the association rules from the RSSI, LQI, SNR and PRR which had been clustered. At last, three dimensional cloud model is employed in WSNs link prediction. Comparing with BP neural network prediction method, the proposed prediction model achieves higher accuracy as simulation experiment results show.

Abstract:In order to address the low accuracy issue of IMU-based(inertial-measure-unit-based) dead reckoning and the difficulty of path optimization between the indoor floors and other problems, a series of work are carried out in this paper. First of all, a three-dimension path optimization algorithm, A-DP, is proposed based on the heuristic dynamic programming. Then, with the optimal path constraint, the HDE algorithm and the accuracy of the direction of travel(SPM-HDE) are improved. Finally, combining with IMU navigation technologies, the navigation in indoor three-dimensional space is accomplished. Test results show that both the efficiency of the algorithm and the accuracy of the dead reckoning are greatly improved.