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Real traffic-data based evaluation of vehicular traffic environment and state- of-the-art with future issues in location-centric data dissemination for VANETs 被引量:1
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作者 Abdul Hafidz Abdul Hanan Mohd. Yazid Idris +2 位作者 Omprakash Kaiwartya Mukesh Prasad Rajiv Ratn Shah 《Digital Communications and Networks》 SCIE 2017年第3期195-210,共16页
Extensive investigation has been performed in location-centric or geocast routing protocols for reliable and efficient dissemination of information in Vehicular Adhoc Networks (VANETs). Various location-centric rout... Extensive investigation has been performed in location-centric or geocast routing protocols for reliable and efficient dissemination of information in Vehicular Adhoc Networks (VANETs). Various location-centric routing protocols have been suggested in literature for road safety ITS applications considering urban and highway traffic environment. This paper characterizes vehicular environments based on real traffic data and investigates the evolution of location-centric data dissemination. The current study is carded out with three main objectives: (i) to analyze the impact of dynamic traffic environment on the design of data dissemination techniques, (ii) to characterize location-centric data dissemination in terms of functional and qualitative behavior of protocols, properties, and strengths and weaknesses, and (iii) to find some future research directions in information dissemination based on location. Vehicular traffic environments have been classified into three categories based on physical characteristics such as speed, inter-vehicular distance, neighborhood stability, traffic volume, etc. Real traffic data is considered to analyze on-road traffic environments based on the measurement of physical parameters and weather conditions. Design issues are identified in incorporating physical parameters and weather conditions into data dissemination. Functional and qualitative characteristics of location-centric techniques are explored considering urban and highway environments. Comparative analysis of location-centric techniques is carded out for both urban and highway environments individually based on some unique and common characteristics of the environments. Finally, some future research directions are identified in the area based on the detailed investigation of traffic environments and location-centric data dissemination techniques. 展开更多
关键词 location-centric data dissemination Geocast routing Vehicular ad hoc networks Analysis of real traffic data VANETs survey Evolution of geocast routing
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Method for integer ambiguity resolution in GPS network RTK 被引量:5
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作者 潘树国 王庆 +1 位作者 柯福阳 邓健 《Journal of Southeast University(English Edition)》 EI CAS 2009年第4期491-495,共5页
A method for integer ambiguity resolution in the global positioning system (GPS) multi-reference station network real time kinematic (RTK) is proposed. First, the barycenter of the triangle of reference stations f... A method for integer ambiguity resolution in the global positioning system (GPS) multi-reference station network real time kinematic (RTK) is proposed. First, the barycenter of the triangle of reference stations for ambiguity resolution is taken as a reference point. The satellite which has the largest elevation angle with the reference point is selected as a reference satellite. The parameters for constructing the weight matrix of carrier phase observation and the criteria for checking the correctness of integer ambiguity resolution of a network are obtained. Then, the wide ambiguity is calculated by a linear combination method of dualband observation. And the LI ambiguity is obtained by a nonionosphere combination method. The Kalman filter is introduced to refine the floating-point solution of ambiguity and estimate the real-time tropospheric delay. Finally, the cofactor matrix of ambiguity is de-correlated by Z-transformation to reduce the searching space of the integer ambiguity solution and improve the efficiency of the least-squares ambiguity decorrelation adjustment (LAMBDA) algorithm. The experimental results show that this method can reliably obtain the integer ambiguity solution among multi-reference stations with 40 epochs. 展开更多
关键词 network real time kinematic AMBIGUITY troposphere: reference satellite least-squares ambiguity decorrelation adjustment
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Improving the initialization speed for long-range NRTK in network solution mode
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作者 ZHANG Ming LÜJinHu +2 位作者 BAI ZhengDong LIU Hui FAN ChengCheng 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第5期866-873,共8页
Initialization speed is one of the most important factors in network real time kinematic(NRTK)performance.Owing to the low correlation among the error sources of reference stations,it is difficult to fix reference sta... Initialization speed is one of the most important factors in network real time kinematic(NRTK)performance.Owing to the low correlation among the error sources of reference stations,it is difficult to fix reference station ambiguities of long-range NRTK quickly.In traditional reference stations ambiguity resolution(AR)methods,baselines are usually solved independently which is called baseline solution(BS)mode in this study.Because the correlations among baselines are not taken into consideration in ambiguities estimation,the AR speed is slow.Generally,tens of minutes or longer time is required to initialize.We propose a network solution(NS)mode approach,in which the correlations among the double-difference ambiguities(DDAs)as well as double-difference ionospheric delays(DDIDs)of different baselines are considered in estimating float ambiguity solutions.Experimental results show that the float ambiguity solutions obtained are more accurate with an improved consistency.Thus,initialization speed is significantly increased by 18%in NS mode. 展开更多
关键词 initialization speed network real time kinematic(NRTK) reference station ambiguity resolution(AR) network solution(NS)mode baseline solution(BS)mode
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