• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1410-1429
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• 2017

Mobility arises naturally in the Internet of Things networks, since the location of mobile objects, e.g., mobile agents, mobile software, mobile things, or users with wireless hardware, changes as they move. Tracking their current location is essential to mobile computing. To overcome the scalability problem, hierarchical architectures of location databases have been proposed. When location updates and lookups for mobile objects are localized, these architectures become effective. However, the network signaling costs and the execution number of database operations increase particularly when the scale of the architectures and the numbers of databases becomes large to accommodate a great number of objects. This disadvantage can be alleviated by a location caching scheme which exploits the spatial and temporal locality in location lookup. In this paper, we propose a hierarchical location caching scheme, which acclimates the existing location caching scheme to a hierarchical architecture of location databases. The performance analysis indicates that the adjustment of such thresholds has an impact on cost reduction in the proposed scheme.

• Journal of Korea Multimedia Society
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• v.6 no.4
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• pp.601-609
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• 2003

In wireless mobile networks, the service area is partitioned into several registration areas (RAs). Every RA is associated with a mobility database called Visitor Location Register (VLR). The VLR is used to achieve the location management of the mobile terminals. When a mobile terminal enters a new RA, the VLR stores the current location information of the mobile terminal before serving any mobile services. At that time, if the VLR is full, the registration procedure fails, and the system can not deliver services to the mobile user under the existing cellular technology To resolve this problem, we propose a VLR overflow control scheme considering mobility of mobile users to accomodate incoming users during VLR overflow. The performance of the proposed scheme is evaluated by an analytic model in terms of costs for the location search and the location update, and compared with those of the overflow control scheme proposed by Lin[1].

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.215-221
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• 2010

This paper introduces development of location estimation and navigation system of mobile robots using USN and LEGO Mindstorms NXT. Developed system includes location estimation, location and navigation information display and navigation control parts. It used ZigBee based USN which was built with CC2431 chip to locate blind node and implemented fuzzy model to improve ability of calculation of distances from reference nodes and location of mobile robots. This paper proposed combination method of location estimation using USN and encoder which is built in motors of mobile robots. Experimental results showed proposed method is superior to the method which used USN only in location estimation and navigating robots. Developed system can locate current position of mobile robots and monitor information from sensor nodes like temperature, humidity and send control signal to mobile robot to move.

• Journal of Advanced Navigation Technology
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• v.12 no.1
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• pp.15-21
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• 2008

In this paper, person monitoring and personal identification information management by using the location positioning device and the location management system based on GPS is analysed and developed. Mobile HTE(Mobile HTE : Mobile Home Terminal Equipment) of the developed system uses the module for transmitting PID(Personal Identification Device) information and the module based on GPS's location information. HTE transmits the received information from Mobile HTE to the Location Management System through the internet system. The Location Management System is developed for person location management and information management.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.25-28
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• 1999

Consider connection-oriented wireless cellular net-works. To establish a circuit or virtual circuit in such a network, a paging message is broadcast over a region at which the destined mobile station is presumed to reside, (identified as a paging area). For an effective paging mechanism, it is desirable to provide the location information of mobile stations to the network. In this paper, we consider a mobile controlled location update scheme under which each mobile station periodically reports its current location information to the network by using an inherent timer (without measuring the power of signals transmitted from base stations). Based on the latest information about a mobile station's location, a paging area is selected to page the mobile station. Note that under this scheme, a mobile station may not yet have reported its location change while sojourning out of the current paging area. In such situation, the mobile station can not receive a paging message destined to it. Frequent location updates can reduce the paging failure rate incurred by mobile stations'sojourning out of the paging area. However, larger bandwidth is needed for location update as the location update rate is increased. On the other hand, as the size of the paging area is increased, the paging failure rate is decreased, while larger bandwidth is required for paging. Thus, we first present a model for mobility, paging and location update processes, and secondly investigate the effect of network parameters on the paging failure rate and the amount of bandwidth used for paging and location update. Finally, we formulate problems to find proper values for the location update rate and paging area size under the constraints on the bandwidth usage levels for location update and paging.

• ETRI Journal
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• v.29 no.1
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• pp.107-109
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• 2007

In location-based services, most trigger technologies have been implemented on the server side by periodically requesting the locations of mobile phones from mobile network servers. However, bottlenecks and communication interruptions occur when the servers are overloaded by trigger requests. In this letter, we propose a new multilevel location trigger specification which distributes the event detecting role to mobile phones and redesigns the location triggering into a multilevel step. Our suggested location trigger specification can reduce bottlenecks caused by triggers in a mobile core network and reduce power consumption caused by embedded GPS devices in mobile phones.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.10
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• pp.1217-1224
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• 1999

이동 호스트들의 위치 정보를 관리하는 것은 이동 컴퓨터 시스템에서 중요한 문제이다. 이동 호스트가 이동할 때 위치 수정과 위치 탐색간에는 상반관계가 존재한다. 본 논문에서는 위치 서버를 이용한 간단한 quorum 기반 분산 동적 위치 관리 방법을 제안한다. 이 방법에서는 이동 호스트들의 위치 정보가 모든 위치 레지스터가 아닌 위치 레지스터들의 부분집합에서 효율적으로 관리되기 때문에 위치 수정 비용과 위치 탐색 비용이 감소된다. 그리고 위치 레지스터들의 부분집합은 동적으로 변하고, 각 위치 서버의 부하는 이동 호스트에 대한 질의율을 고려하므로 균등해진다. 제안된 알고리즘의 성능은 위치 수정비용과 위치 탐색비용의 전체비용으로 평가되었고, Prakash의 알고리즘과 비교되었다.Abstract Managing location information of mobile hosts is an important issue in mobile computing systems. There is a trade-off between location update and search, when a mobile host moves. This paper proposes a simple quorum-based distributed dynamic location management method using location registers. The cost of location updates and searches is reduced by our method because the location information of mobile hosts is managed efficiently in a subset of location registers instead of in all location registers. In our method, the subset of location registers is dynamically changed, and the load of each location register is balanced by considering query rate for mobile hosts. The performance of proposed algorithm is evaluated in terms of the total cost of a location update and a location search, and is compared with Prakash's algorithm.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.287-290
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• 2003

In recent years, one of the main trends of GIS is to construct and provide realistic and human-perceptible information of spatial object using video data. The rapid progress of wireless mobile technology makes the multimedia source using video data possible on mobile environment. Instead of traditional map-based service, video-based location services, that provide video data as location context, would be of interest in connection with various mobile applications requiring location service, such as telematics, LBS, etc. In this paper, we present the location service system using geo-referenced video on wireless mobile environment.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.581-594
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• 2003

Recently, a location management is being more important in mobile communication systems due to an explosive increase of mobile users. Current systems have used a concept of location area. Based on this concept, a mobile user performs a location update whenever it moves into a new location area. However, this scheme can not avoid unnecessary location updates when a mobile user moves around with high movement rate as compared to call arrival rate. That results in tremendous location management cost. To overcome this drawback, our proposal divides service areas into two sets: One is a set of areas that mobile users move with high speed and another is a set of areas that they move with low speed. After establishing these two sets, this paper employs different location tracking schemes for each sets. Generally, most mobile users with high speed have a low CMR and a regular direction until they arrive at their destination. Using such the moving behavior, systems can predict a mobile user's next location area in advance. When the mobile user moves into the predicted location, our proposal does not perform a location update. Thus, it can reduce overall location management cost. The Markov model is used to analyze the performance of our proposal. Using the model, this paper compares our proposal with IS-41 and TLA. The analytic results show that as CMR grows lower, an overall cost of our proposal becomes less, particularly if a mobile user frequently moves into the specific location are predicted by mobile systems. Also, our proposal has a better performance than other two schemes when the communication cost between HLR and VLR is high.

• Journal of the Korean Data and Information Science Society
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• v.18 no.3
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• pp.757-766
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• 2007

Location services are used in mobile ad hoc and hybrid networks to locate either the geographic position of a given node in the network or a data item. One of the main usages of position location services is presented in location based routing algorithms. In particular, geographic routing protocols can route messages more efficiently to their destinations based on the destination node's geographic position, which is provided by a location service. In this paper, we propose an adaptive location service on the basis of fuzzy logic called FHLS (Fuzzy Hierarchical Location Service) for mobile ad hoc networks. The adaptive location update scheme using the fuzzy logic on the basis of the mobility and the call preference of mobile nodes is used by the FHLS. The performance of the FHLS is to be evaluated by a simulation, and compared with that of existing HLS scheme.