Abstract: A portable wireless terminal for performing visible light communication with other devices through free space includes an optical detector for generating an electrical signal after photoelectrically converting some of optical signal input from free space and outputting the electrical signal; a reflector for retro-reflecting the others of the optical signal incident on the concave grooves, the reflector having a reflection surface on which at least one concave groove is formed; and a modulator for outputting the retro-reflected optical signal after data modulation.

Abstract: A peer-to-peer communication method for NFC is provided. A link-level security is started by exchanging a link-level security request and a link-level security response between an initiator terminal and a target terminal, then transmission data are encrypted at link-level security layers of the initiator terminal and the target terminal, and the encrypted data are exchanged between the initiator terminal and the target terminal. The link-level security is released by exchanging a link-level security release request and a link-level security release response between the initiator terminal and the target terminal.

Abstract: A method and an apparatus for determining mutual time difference between base station signals in an asynchronous code division multiplexing access (CDMA) system. The method comprises the steps of: measuring mutual time difference of signals transmitted between at least two base stations; determining all possible paths between said at least two base stations; and providing weights to the measured mutual time difference for said all possible paths. The apparatus comprises: a location measurement unit for measuring mutual time difference of signals transmitted between at least two base stations; a mobile user location center for receiving the mutual time difference of the signals measured by the location measurement unit, determining all possible paths between said at least two base stations, and providing weights to the measured mutual time difference for said all possible paths.

Abstract: An apparatus for calculating satellite acquisition information for controlling a position determination entity (PDE) to determine a position of the MS in a network assisted GPS system comprising an MS containing a GPS receiver and the PDE containing a reference station GPS receiver, the apparatus comprising a satellite data collector for collecting satellite orbital information transferred from a plurality of satellites to the reference station GPS receiver; a pseudo range calculator for receiving the satellites' position coordinates calculated based on the satellite orbital information and calculating a pseudo range between the MS and a satellite observed by the MS using the received information; a pseudo velocity calculator for receiving satellites' velocity information calculated based on the satellite orbital information; and a satellite acquisition information calculator for calculating a code phase using the pseudo range, calculating a Doppler shift using the pseudo velocity, and calculating the satelli

Abstract: A pseudolite PRN code assigning system and method are provided. In the system, a management server collects information related to PRN codes of GPS satellites, and a plurality of pseudolites (pseudo satellites) modulate transmission signals with PRN codes assigned from the management server.

Abstract: A pseudolite PRN code assigning system and method are provided. In the system, a management server collects information related to PRN codes of GPS satellites, and a plurality of pseudolites (pseudo satellites) modulate transmission signals with PRN codes assigned from the management server.

Abstract: A traffic information service apparatus using an ad-hoc network and a method for controlling the same. The apparatus provides an ad-hoc network between vehicles and roadside devices, and collects/provides traffic information using the ad-hoc network. The method for providing a user with traffic information, comprising the steps of a) allowing vehicles to broadcast their registration messages to create an ad-hoc network, and creating the ad-hoc network between the vehicles on the basis of the registration messages, b) allowing a Road Side Equipment (RSE) to receive the registration messages broadcast from the vehicles, and collecting traffic information from the registration messages, and c) allowing the RSE to transmit the traffic information to a traffic information service center.

Abstract: A system and method for communicating vehicle management information between vehicles using an ad-hoc network. The system and method forms a routing path based on vehicle management information of individual vehicles, and communicates the vehicle management information between the vehicles along the routing path. A source vehicle collects its own vehicle driving information, and creates vehicle management information of the source vehicle based on the vehicle driving information. The source vehicle sets up a routing condition composed of predetermined vehicle traveling requirements based on the vehicle management information, and transmits a vehicle management information message having the routing condition and the vehicle management information to nearby vehicles. The nearby vehicles search for the routing condition upon receiving the vehicle management information message, and determine whether to route the vehicle management information message according to the routing condition.

Abstract: An apparatus for calculating satellite acquisition information for controlling a position determination entity (PDE) to determine a position of the MS in a network assisted GPS system comprising an MS containing a GPS receiver and the PDE containing a reference station GPS receiver, the apparatus comprising a satellite data collector for collecting satellite orbital information transferred from a plurality of satellites to the reference station GPS receiver; a pseudo range calculator for receiving the satellites' position coordinates calculated based on the satellite orbital information and calculating a pseudo range between the MS and a satellite observed by the MS using the received information; a pseudo velocity calculator for receiving satellites' velocity information calculated based on the satellite orbital information; and a satellite acquisition information calculator for calculating a code phase using the pseudo range, calculating a Doppler shift using the pseudo velocity, and calculating the satelli

Abstract: A method and an apparatus for determining mutual time difference between base station signals in an asynchronous code division multiplexing access (CDMA) system. The method comprises the steps of: measuring mutual time difference of signals transmitted between at least two base stations; determining all possible paths between said at least two base stations; and providing weights to the measured mutual time difference for said all possible paths. The apparatus comprises: a location measurement unit for measuring mutual time difference of signals transmitted between at least two base stations; a mobile user location center for receiving the mutual time difference of the signals measured by the location measurement unit, determining all possible paths between said at least two base stations, and providing weights to the measured mutual time difference for said all possible paths.