• 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.

• The KIPS Transactions:PartA
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• v.13A no.5 s.102
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• pp.435-444
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• 2006

Recently, various applications of location trigger service have been required and developed as users of location-based services are increasing. The location trigger is detecting event of entering in, existing in or leaving from pre-specified area, and then alerting by short message service, an e-mall or servicing other pre-defined action to mobile subscribers. The conventional methodology of supporting location trigger is detecting location trigger events as periodical requesting location of mobile communication terminal to location gateway server in mobile communication network. But these conventional methods cause mobile communication interruption when the location trigger services are overloaded; thereby inducing performance of core server to be fell off. So in this paper, we have studied a new location trigger technology, named multilevel location trigger, to reduce mobile core network sewer triggering bottleneck and power consumption caused embedded GPS device of mobile phone. Actually, as design and evaluating the performance of location trigger after building test-bed environment, we contribute toward improving echnology of location trigger.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.61-67
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• 2011

The GPS new civil signal is modulated on the L2 carrier at a frequency of 1227.6MHz. The L2C signal is composed of two multiplexed code signals, which include CM code with a 10,230 chip sequency repeating every 20ms, and CL code which has a 767,250 chip sequency repeating every 1.5 seconds. Thus, the new civil signal have much improved cross correlation properties so that the position fixing can be possible even with very weak signals. However, it requires very long acquisition time because of its long code length. This paper presents an efficient signal acquisition method for L2C AGPS receiver. Snapshot mode and coarse time assistance are assumed and total integration time is given by 1.5 sec. By SNR worksheet and computer simulation, it is proven that L2C signal can be acquired with very weak power less than -150dBm. Considering the acquisition time and the sensitivity, it is recommended that the highest power signal is acquired with CM code first to reduce TTFF. By the timing synchronization, at this time, search space of the code phase for other signals can be greatly reduced so that CL code can be used in signal acquisition to maximize sensitivity with small computation.

• Journal of Korea Spatial Information System Society
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• v.11 no.4
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• pp.47-55
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• 2009

As the wireless internet technology such as mobile phone, WIBRO, HSDPA develops, customized location-based services for traffic, tourism, shopping, and emergency relief has lately attracted attention. For giving customized services. we should consider dynamic characteristics of moving object which continuously change their location. In this paper, we define the context trigger type of moving object and design triggering method for processing context generated by moving object. Also we propose location-based push service platform including context trigger of moving object for supporting location-based information to user. The proposed system gathers moving object stream from the terminal based on MS-assisted or Stand-alone positioning mode of embedded GPS in terminal extract user context by user device agent, and send context information to server.