Wireless sensor networks consist of two kinds of nodes: the anchor and the Agent. The anchor is equipped with special hardware to obtain precise location information and employed to derive the locations of Agents. Due to the resource-limited nature of single sensors, actively participating nodes should be kept to a proper number. Based on an investigation on the trade-off between the localization accuracy and the computation complexity of sensor nodes, we propose a distributed algorithm to select subsets of anchor nodes for localization and analyze this algorithm regarding the energy consumption of every node.

The global navigation satellite systems (GNSS) is used more and more widely in military and civilian, but because of low sending power of GNSS signal, and other weakness, the safety and protection related issues have attracted wide attentions. However, most literatures about this were just qualitative enumeration or only focused on the navigation performance itself. This work studied this question from the view of the main materiel system that GNSS served for. We analyzed the impacts of GNSS receiver’s safety & protection ability on the operational utility of main materiel system based on a mathematical model. First of all, a mathematical function which contains several protection related parameters was used to describe the issues, followed with detail quantitative methods for those parameters. Then a case study was shown to demonstrate the application of the model proposed before. Based on the case study, it appears that the method has great potential and applicability to safety & protection ability analysis of GNSS.

To achieve the distributed composition of the SMP2 simulation models under the service-oriented architecture, a proxy-based composition method was promoted. According to the traditional SMP2 model composition mode and the feature of SOA, four proxy-based composition modes were proposed, including: component composition, interface composition, event composition and field composition. Then the functional needs of model proxy were analyzed and the composition processes were defined, the initialization and composition process of SMP2 models were detailed. Finally, the model proxy interface was designed to support the implementation of model proxy.

A new localization method has been proposed to overcome the limitations of systems relying on GPS or other terrestrial infrastructure. This method fuses both pseudorange measurements from GNSS satellites and RSSI-based ranging measurements between peers of a wireless network, and uses improved collaborative subtree algorithm to partition the network. In each collaborative subtree, the nodes’ positions can be computed by using the least square algorithm based on Taylor series expansion-based. Simulation results showed that this method improves both availability and positioning accuracy.

â??We propose a service-oriented modeling and simulation (M&S) method based on simulation model portability 2 (SMP2) to simulate the performance of the Global Navigation Satellite System (GNSS). The proposed method can be utilized to construct large complex simulation systems, such as GNSS, to determine the reusability, composability, and interoperability of heterogeneous simulation resources. A service-oriented SMP2 M&S framework with its conceptual framework, system architecture, and system engineering process is first introduced. The development and composition of the SMP2 model as well as the schedule method are then discussed in detail. Lastly, a service-oriented SMP2 M&S environment is designed and implemented, and the regional dilution of precision performance of the GALILEO Navigation Satellite System in China is analyzed based on the architecture and method.