a b s t r a c tA great deal of research achievements on localization in wireless sensor networks (WSNs) has been obtained in recent years. Nevertheless, its interesting challenges in terms of cost-reduction, accuracy improvement, scalability, and distributed ability design have led to the development of a new algorithm, the Push-pull Estimation (PPE). In this algorithm, the differences between measurements and current calculated distances are modeled into forces, dragging the nodes close to their actual positions. Based on very few known-location sensors or beacons, PPE can pervasively estimate the coordinates of many unknown-location sensors. Each unknown-location sensor, with given pair-wise distances, could independently estimate its own position through remarkably uncomplicated calculations. Characteristics of the algorithm are examined through analyses and simulations to demonstrate that it has advantages over those of previous works in dealing with the above challenges.

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Future wireless systems are expected to be characterized by the coexistence of different radio access technologies (RATs) resulting in complex heterogeneous wireless environments. In parallel with this, the tremendous demand for spectrum has inspired the requirement of dynamic spectrum management (DSM). This paper aims at designing a cell based dynamic spectrum management (CBDSM) scheme to enhance the spectrum utilization and maximize the profit of operators in wireless heterogeneous networks. The system architecture and the functional modules supporting the CBDSM scheme are designed. As a fundamental issue in spectrum management, the inter-system interference issue is solved in the proposed CBDSM scheme. Furthermore, game theory, which is a potential tool for studying the distributed autonomous resource optimization algorithms, is applied to design a spectrum trading algorithm enabling the heterogeneous wireless networks to dynamically trade spectrum and to share the profit. In the algorithm, we take into account the economic value of the spectrum of wireless systems in order to guarantee the rationality for the spectrum trading. The simulation results show that the proposed CBDSM scheme effectively improves the spectrum utilization and the profit of operators while it reduces the mutual interference between wireless networks to a tolerable level.

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Joint session scheduling (JOSCH) enables traffic to be split and transmitted over multiple radio access networks (RANs) simultaneously, which improves the quality-of-service (QoS) in terms of transmission rate, reliability and stability. Transmission synchronization is one of the key issues which JOSCH should consider, as it has direct effect on the performance of buffer management and data reassembly at the traffic receiver. In this paper, a segment-based adaptive JOSCH mechanism was proposed to guarantee the transmission synchronization during multi-RANs simultaneous transmission. The proposed mechanism restrains the delay differences between different RANs, by adjusting the traffic allocation ratios to multiple transmission RANs adaptively, based on the feedback from traffic receiver. System architecture and functional modules are designed to support the proposed mechanism. Meanwhile, a generic transport protocol model supporting multi-RANs transmission is introduced as well. Simulation results reveal that the proposed JOSCH mechanism well adapts to the dynamic change of network conditions, and guarantees the synchronization and stability of transmission.

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Abstract-We consider the scenario that N sensors collaborate to observe a single event. The sensors are distributed and can only exchange messages through a network to reach a consensus about the observed event. In this paper, we propose a very robust and simple method using broadcast gossip algorithm to solve the distributed hypothesis testing problem. The simulation result shows that our method has good performance and is very energy efficient comparing to existing methods.