Hong Tao Hou

Study on Safety & Protection Ability of GNSS Receiver from the View of Main Materiel System

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.

Cooperative Positioning Based on Hybrid Information

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.

A Proxy-Based Composition Method for Distributed SMP2 Models

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.

Reliability Analysis for the Navstar Based on State Probability of the Constellation

The definition for the constellation availability of the navigation system is given firstly, and then calculates the availability of a single satellite by using Markov processes, and establishes the model based on the state probability of the constellation, to achieve mapping model from component reliability of the single satellite to the constellation availability. Finally, we analysis the regional availability performance of the GNSS by the algorithm, which can fit and satisfy the requirements of contradiction between accuracy and rapidity for analysis of availability for constellation of GNSS.

A Parallel Simulation Method for Performance Analysis of GNSS

In this paper, we proposed a parallel simulation method for performance analysis of the Global Navigation Satellite System (GNSS) based on simulation model portability 2(SMP2) and service-oriented modeling method. GNSS is a space engineering system with a large-scale and complex structure, and the proposed method can be used to construct large complex simulation systems to gain the reusability, composability and interoperability of heterogeneous simulation resources. Firstly, the method including the conceptual framework, system architecture and system engineering process is introduced. Then the parallel model development, composition and schedule method are detailed respectively. Finally, a distributed M&S environment based on service-oriented SMP2 is designed, and an example of navigation system volume simulation is given to validate the whole method.

A Model Integration Framework Based Portability for GNSS Simulation

Performance Simulation for Global Navigation Satellite System (GNSS) that be used for performance simulation and evaluation analysis of the GNSS, is a part of the critical algorithm test and system index analysis for GNSS. In this article, the requirements of GNSS are analyzed firstly, and the characteristic of model portability for GNSS is studied, then the model integration framework based on Simulation Model Portability is proposed. The system architecture consists of model design, development, integrating, executing and analysis. Lastly, the regional performance of GALILEO Navigation Satellite System in China is tested and analyzed based on the integration framework.

An Anchor Selection Algorithm in Wireless Sensor Network

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.

Peer-to-Peer Cooperative Positioning between GNSS Receivers

Global navigation satellite system (GNSS)-like the Global Positioning System (GPS) and the future Chinese Beidou system-can deliver very good position estimates under optimum conditions. However, especially in critical positioning scenarios like urban canyons or indoor environments the performance loss would be very high or GNSS based positioning is even not possible. Based on the concept of Cooperative Positioning in acquiring real-time positioning information of mobile robots, GNSS Peer-to-Peer Cooperative Positioning (P2P-CP) technology is proposed to overcome the shortage of GNSS positioning. Terrestrial ranging and communication modular are equipped with GNSS receivers to construct real-time CP network. The terrestrial ranging and communication modular respectively used for distance measurement and communication between nearby GNSS receivers, distributed algorithms are applied to fuse pseudorange and neighbors nodes distance to calculate the nodes position. Current research results of GNSS CP show that this new positioning strategy gets equal or better precision with less time cost compared with Assisted GNSS (AGNSS).

Modeling and Analysis of the Threats to GNSS

The vulnerability of the global navigation satellite systems (GNSS) makes it susceptible to a variety of threats, so it is significant to study the effects of each threat on GNSS performance. To analyze the impacts of different threats, a dynamic master logic diagram (DMLD) based modeling and analysis method was presented. First the relationships between threats and GNSS performance were built through a quadric associations by DMLD symbols, then qualitative and quantitative analysis was done via DMLDs great reasoning power, at last qualitative and quantitative analysis could show engineers and researchers the effects they concerned about and also could support the improvement of GNSSs defense and protection capability. The DMLD based method provides engineers a feasible way for threats modeling and analysis.

An Algorithm of Inter Satellite Links Based on Ranging and Access

It is a problem to build Inter Satellite Links so that Region Navigation System has optimal performance. Therefore, the article puts forward an algorithm, which synthesizes the time of satellites accessed and the distance of satellites. And then it carries out a simulation in navigation system to certify the superiority of the algorithm. The experimental result shows that the ISLs can effectively improve the performance of navigation system. And comparing with the traditional Minimum Distance Algorithm, the proposed algorithm has the same effect on improving the performance of navigation system and needs fewer times of changing links.