Hongsong Zhu

Nonidentical Linear Pulse-Coupled Oscillators Model With Application to Time Synchronization in Wireless Sensor Networks

Similar to other cyber infrastructure systems, as wireless sensor networks become larger and more complex, many classic algorithms may no longer work efficiently. This paper presents a wireless sensor network time synchronization model that was initially inspired by synchronous flashing of fireflies. Synchronous flashing of fireflies is an interesting phenomenon that has been studied for decades. A variety of models have been proposed to explain this phenomenon, among which is the pulse-coupled oscillators model that models fireflies as oscillators. The oscillators in such a model interact only through discrete pulses, similar to the flashing of fireflies. In this paper, we propose a new nonidentical linear pulse-coupled oscillators model and use the model to analyze synchronization of pulse-coupled oscillators with different frequencies. The conditions to achieve and maintain synchronization are derived, and then, the results are used to prove that the oscillators in the model can achieve synchronization eventually, except for a set of frequencies with zero Lebesgue measure. Furthermore, through simulations and implementation on a wireless sensor network testbed, we demonstrate that the proposed nonidentical linear pulse-coupled oscillators model can be used in designing lightweight scalable time synchronization protocols for distributed systems.

Adaptive TDMA slot assignment protocol for vehicular ad-hoc networks

This paper proposes a novel adaptive time division multiple access (TDMA) slot assignment protocol (ATSA) for vehicular ad-hoc networks. ATSA divides different sets of time slots according to vehicles moving in opposite directions. When a node accesses the networks, it choices a frame length and competes a slot based on its direction and location to communication with the other nodes. Based on the binary tree algorithm, the frame length is dynamically doubled or shortened, and the ratio of two slot sets is adjusted to decrease the probability of transmission collisions. The theoretical analysis proves ATSA protocol can reduce the time delay at least 20% than the media access control protocol for vehicular ad-hoc networks (VeMAC) and 30% than the ad-hoc. The simulation experiment shows that ATSA has a good scalability and the collisions would be reduced about 50% than VeMAC, channel utilization is significantly improved than several existing protocols.

Linear Pulse-Coupled Oscillators Model—A New Approach for Time Synchronization in Wireless Sensor Networks

Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we analyze the synchronization condition of two- and multi-oscillators system, and propose a linear pulse-coupled oscillators model. We prove that the proposed model can achieve synchronization for almost all conditions. Numerical simulations are also included to investigate how different model parameters affect the synchronization. We also discuss the implementation of the model as a new approach for time synchronization in wireless sensor networks.

Design and Implementation of Smart Home Linkage System Based on OSGI and REST Architecture

Smart Home, a typical application scene of Internet of Thing, recently has attracted wide attention from industry to academic circles. There are many heterogeneous devices in smart home environment, which makes it difficult to integrate, make united management and work with each other for different subsystems. Based on the above issues, this paper designs and implements a smart home linkage system based on the OSGI and REST architecture. It consists of four subsystems, which are as follows: environment perception subsystem, home appliances control subsystem, video monitoring subsystem and intelligent analysis and linkage control subsystem. Combined the advantages of OSGI and REST, the software architecture of it has solved three issues mentioned above. On the basis of prototype system, this paper makes several concerning experiments in the overall system delay and linkage delay to verify the performance of it.

Efficient Deterministic Anchor Deployment for Sensor Network Positioning

Sensor network positioning systems have been extensively studied in recent years. Most of the systems share a common assumption that some known-position anchor nodes have existed. However, a more fundamental question is always being overlooked, that is, how to acquire the anchors position. In general, GPS-based measures and the artificial calibration are two dominant methods to acquire anchor positions. Due to the high energy cost and failures in occlusion regions of the GPS modules, the artificial calibration method is adopted extensively. Nevertheless, numerous disadvantages of the artificial calibration, such as the expensive labor cost and error-prone features, also make it hard to be an efficient solution for the anchor positioning. For this reason, we design an efficient mapping algorithm between anchors and their positions (MD-SKM) to avoid the complicated artificial calibration. Additionally, we propose a best feature matching (BFM) method to further relax the restriction of MDS-KM where three or more calibrated anchors are needed. We evaluate our MDS-KM algorithm under various topologies and connectivity settings. Experiment results show that at a slightly higher connectivity level, our algorithm can achieve the exactly correct matching between anchors and their positions without any calibrated anchors.

Distributed Middleware of Large-Scale Wireless Networks

1 Department of Computer Science and Technology, China University of Petroleum, Beijing 102249, China 2 Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China 3Department of Electrical Engineering, University of North Texas, Denton, TX 76203, USA 4 Institute of Information Engineering, Chinese Academy of Sciences, Beijing 100093, China 5 Department of Information & Communication Systems, Hohai University, Changzhou 213022, China

An energy-efficient link quality monitoring scheme for wireless networks

Link quality is one of the most important factors that affect the performance of wireless networks. In a densely deployed wireless network, continuous link quality monitoring consumes significant amount of energy and bandwidth at each node. In this paper, we propose a sensitivity model and a spatial correlation model that can be used to derive a set of deputy links to monitor, instead of monitoring all of the links in the network. The proposed scheme can improve energy efficiency of the link quality monitoring process. A greedy algorithm is presented to derive the deputy links set based on three different optimization objective functions. Performance of the proposed method is studied extensively and it is shown that the proposed method can save almost 90% energy in typical simulation scenarios than the method of monitoring all links. We also demonstrate that the energy consumption of the greedy deputy set-based method is upper-bounded. Copyright