Browsing by Author "Feng, KT"

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An efficient geometry-constrained location estimation algorithm for NLOS environments
(2005)
Chen, CL
;
Feng, KT
;
電信工程研究所
;
Institute of Communications Engineering
Mobile location estimation has attracted a significant amount of attention in recent years. The network-based location estimation schemes have been widely adopted based on the radio signals between the mobile device and the base stations. The two-step Least Square (LS) method has been studied in related research to provide efficient location estimation of the mobile devices. However, the algorithm results in inaccurate location estimation with the existence of the Non-Line-Of-Sight (NLOS) errors. A Geometry-constrained Location. Estimation (GLE) algorithm is proposed in this paper with the consideration of different. geometric layouts between the mobile device and its associated base stations. In order to enhance the precision of the location estimate, the GLE scheme is designed to incorporate the geometric constraints within the formulation of the two-step LS method. The proposed GLE scheme can both preserve the computational efficiency from the two-step LS algorithm and obtain precise location estimation under NLOS environments. Numerical results demonstrate that the proposed GLE algorithm can achieve better accuracy, comparing with other existing schemes, in mobile location estimation.
Hybrid location estimation and tracking system for mobile devices
(2005)
Chen, CL
;
Feng, KT
;
電信工程研究所
;
Institute of Communications Engineering
Mobile location estimation has attracted lots of attention in recent years. The location algorithms for the mobile devices can generally be categorized into the network-based and the satellite-based systems. Both types of system have their advantages and limitations under different environments (i.e. urban, suburban, or rural area). In order to provide adaptation to various scenarios for location estimation, a hybrid location scheme, which combines both the satellite-based and the network-based signals, is proposed in this paper. The proposed scheme utilizes the two-step Least Square method for estimating the three-dimensional position (i.e. the longitude, latitude, and altitude) of the mobile devices. The Kalman filtering technique is exploited to both eliminate the measurement noises and to track the trajectories of the mobile devices. A fusion algorithm is employed to obtain the final location estimation from both the satellite-based and the network-based systems. Numerical results demonstrate that the proposed hybrid location scheme provides accurate location estimation by adapting itself under different environments.
Predictive mobility and location-aware routing protocol in mobile ad hoc networks
(2005)
Lu, TE
;
Feng, KT
;
電信工程研究所
;
Institute of Communications Engineering
In recent years, many location-aware routing protocols have been proposed for the mobile ad hoe networks. The routing performance is improved by exploiting the position information of the mobile nodes. However, the mobility characteristics of the mobile nodes have not been taken into consideration. In this paper, the proposed Predictive Mobility and Location-Aware Routing (PMLAR) algorithm incorporates the moving behaviors of the mobile nodes in the protocol design. The region for packet forwarding is determined by predicting the future trajectory of the destination node. The routing performance can be effectively improved by adopting the prediction mechanism of the proposed PMLAR algorithm. Simulation results show that the PMLAR algorithm outperforms other routing protocols under different network topologies.
Velocity and location aided routing for mobile ad hoc networks
(2004)
Feng, KT
;
Lu, TE
;
電信工程研究所
;
Institute of Communications Engineering
Many Location-aware routing protocols have been proposed for the mobile ad hoc networks in recent years. The efficiency of the routing protocols can be improved by considering the location information of the mobile nodes. However, the mobility characteristics of the mobile node have not been taken into account in most of the related work. In this paper, the proposed Velocity Aided Routing (VAR) protocol determines its packet forwarding scheme based on the relative velocity between the intended forwarding node and the destination node. The routing performance can be further improved by the Velocity and Location Aided Routing (VLAR) protocol, which combines the Location Aided Routing (LAR) protocol with the VAR algorithm. Two types of motion predictive models, the Gauss-Markov Mobility Model and the Constant Speed Mobility Model, are incorporated in the design of the VAR and VLAR algorithms. Simulation studies show that the proposed VLAR protocol outperforms other routing algorithms, especially for confined network topologies with higher mobility.