Abstract: Provided is a device for tracking polarizations. A receiving polarization tracking device includes a feeder for finding vertical and horizontal vector components by receiving vertical and horizontal polarizations, a polarization estimator for estimating distortion of polarizations using the vertical and horizontal vector components outputted from the feeder, a polarization controller for controlling amplitudes and phases of vertical and horizontal polarizations based on information about the estimated distortion from the polarization estimator and an output signal from the receiving polarization tracking device, and a combiner for combining the vertical and horizontal polarizations controlled from the polarization controller.

Abstract: Disclosed is an interaction method between an automatic repeat request (ARQ) and a hybrid automatic repeat request (HARQ) in a system having a long roundtrip delay. A transmission window for the ARQ is operated using inner feedback information from the HARQ, and a waiting window is operated using ARQ status information.

Abstract: Provided are a time synchronization method and a frequency offset estimation method using the same in an OFDM system. The time synchronization method using a preamble transmitted from a transmitter to a receiver in the OFDM communication network includes the steps of: a) calculating a moving sum of a first sequence and a second sequence obtained by a product of neighboring elements in a received signal when the received signal containing a preamble is received from the transmitter; b) estimating a location of the received signal corresponding to the moving sum having a maximum value; and c) acquiring a time synchronization with respect to the received signal, based on the estimated location, wherein the first sequence is obtained from a product of neighboring elements in the preamble and a correlation value obtained by correlating another sequence with the first sequence is smaller than a predetermined value.

Abstract: A transmission apparatus and method for implementing frequency selectivity in a multi-beam satellite system that transmits a signal to user equipment through one or more antenna feed groups. The transmission apparatus includes: an antenna feed group selecting unit configured to select one or more antenna feed groups from the one or more antenna feed groups; a cyclic delay offset determining unit configured to determine a cyclic delay offset according to a determination result of the antenna feed group selecting unit; and a transmitting unit configured to apply the cyclic delay offset determined by the cyclic delay offset determining unit to a signal to be transmitted through the one or more antenna feed groups selected by the antenna feed group selecting unit, and to transmit a resultant signal.

Abstract: Provided is a system for collecting and managing rainfall attenuation data and rainfall intensity data in a satellite communication system. The system may include: a satellite transmitter to transmit a satellite beacon signal; a Global Positioning System (GPS) to transmit a GPS signal; at least one data collecting apparatus to generate rainfall attenuation data about the satellite beacon signal when the satellite beacon signal is received from the satellite transmitter, and to generate rainfall intensity data within a valid path length of rainfall attenuation, to extract time information from the GPS signal, and to assign the time information to the rainfall attenuation data and the rainfall intensity data; and a data managing apparatus to receive, from the at least one data collecting apparatus, the rainfall attenuation data and the rainfall intensity data assigned with the time information, and to manage the received rainfall attenuation data and rainfall intensity data.

Abstract: A signal processing technology for allowing a repeater to transmit a signal received from an external apparatus to a terminal is provided. In a satellite system, a signal transmitted from a satellite or transmitted to a satellite is subject to a low order modulation, and a terrestrial repeater performs a high order modulation on signals and retransmits the signals.

Abstract: Provided are a non geostationary satellite orbit (NGSO) communication apparatus that extends an operation time using an ancillary territory component (ATC) and reduces a number of satellites, and an ATC and an operating method thereof. The NGSO communication apparatus extends an operation time using an ATC and reduces a number of satellites from a first ATC that communicates with a mobile earth station (MES), and a second ATC that communicates with the first ATC to relay data between the MES and the satellite when the first ATC is unable to communication with the satellite revolving along an orbit.

Abstract: A communication method and apparatus using a symbol interleaver in a long term evolution (LTE)-based satellite communication system are provided. The communication method may include determining whether to use an interleaver based on service information, and interleaving the data using the symbol interleaver designed based on interleaver information. Also, the communication method may include generating random data using a timer and interleaving the random data.

Abstract: A method of receiving a global navigation satellite system (GNSS) signal in a GNSS reception apparatus is provided. The method includes the steps of: measuring channel quality for each frequency band; selecting a plurality of reception channels by using the measured channel quality; reconfiguring an operating parameter of the reception apparatus in accordance with the reception channel; and receiving a signal by using the reconfigured operating parameter.

Abstract: Provided is a communication method of a mobile terminal in an orthogonal frequency division multiplexing (OFDM) based multi-beam satellite system reusing the same frequency band for all the beams, the method including: receiving location information of the mobile terminal from a satellite to determine a location of the mobile terminal within multiple beams; determining a subcarrier group for a communication with the satellite according to the location of the mobile terminal within the multiple beams; and communicating with the satellite using the subcarrier group for the communication with the satellite.

Abstract: Disclosed is a communication method of a satellite mobile communication system. The communication method of a satellite mobile communication system, includes: receiving system information indicating frame intervals in which first user equipments using a satellite radio interface in commonality with a terrestrial radio interface do not perform communications from a base station; accessing the base station in the rest frame intervals other than frame intervals in which the first user equipments do not perform communications, based on the system information; transmitting the system information from the base station to second user equipments using a satellite radio interface optimized for satellite environment; and accessing the base station in the rest frame intervals based on the system information received in the second user equipments.

Abstract: A method and mobile communication terminal for handover in a mobile communication network including at least one mobile communication base station and a communication satellite.

Abstract: Provided is an iterative residual frequency and phase compensation apparatus for an OFDM system and a method thereof. The apparatus includes: a first classifying unit for classifying symbol sequences by each subcarrier wave; a soft-decision calculating unit for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a classifying unit for classifying the soft-decision values by a carrier wave; a frequency estimating unit for estimating a residual frequency error of each carrier wave using the soft-decision value; a phase estimating unit for estimating an average residual phase error using the soft-decision value; a frequency and phase compensating unit for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffer for temporally storing the compensated symbols to provide it to the first classifying unit.

Abstract: A personal portable terminal and an operating method of a multimedia terminal device are provided, and more particularly, a multimedia terminal device, an operating method of the multimedia terminal device, and a personal portable terminal are provided. The multimedia terminal device may receive bidirectional content and additional service information corresponding to the bidirectional content, may classify the received additional service information from the received bidirectional content, and may transmit the classified additional service information to a personal portable terminal that is registered in advance and that is connected wired or wirelessly to the multimedia terminal device.

Abstract: Provided is mobile satellite communication method and apparatus. The satellite communication method includes detecting a location of a terminal, determining a signal transmission scheme for the terminal using the terminal location, determining a subcarrier region to transmit a signal to the terminal using the location of the terminal, and communicating with the terminal using the determined signal transmission scheme and the determined subcarrier region.

Abstract: A power controlled adaptive modulation and coding (AMC) scheme in a satellite communications system includes: calculating, by a user terminal, a received signal-to-noise ratio (SNR) through a packet received from a base station; removing a power control level applied to a packet received before the received packet from the calculated received SNR, and deciding the value obtained by decreasing the calculated received SNR by the power control level; deciding an AMC mode based on the decided received SNR; determining whether power control is required, and deciding a required power control magnitude depending on a channel state positioned in the AMC mode range; transmitting the decided AMC mode and the decided power control information to the base station through channel quality indicator (CQI) feedback; and applying the AMC mode based on information received, and increasing a power by a power control magnitude decided from the received information.

Abstract: Disclosed is a sensing apparatus, a network system, and a controlling method on the basis of a satellite. A satellite-based sensing network system, comprising: a plurality of satellite transmitters that collect information on a peripheral environment and an operating state, and transmits it to peripheral satellites; a satellite wireless receiving/display device that directly receives and displays the information collected from the satellites; a ground control center that receives, stores, and analyzes the information collected from the satellites; and a management center that maintains and repairs the satellite transmitter based on the analyzed results.

Abstract: A service providing method in a satellite communication system includes: confirming positions of terminals when the terminals existing within a service area and intended to receive a service is connected to a satellite base station or a complementary terrestrial component; confirming first terminals, which communicate with the satellite base station, and second terminals, which communicate with the complementary terrestrial component, according to the positions of the terminals; allocating resources usable when communicating with the first terminals and resources usable when communicating with the second terminals; and providing a service to the terminals by using the allocated resources through multi-beams of the satellite base station and multi-beams of the complementary terrestrial component.

Abstract: In a system where satellite communication using multi-beams is performed for each group including a plurality of beams, a required data transmission rate of each beam is detected for each group, more traffic resources are allocated to a beam having a higher required data transmission rate than other beams based on the detection result, and data traffic transmitted to each beam in the group is adaptively controlled.

Abstract: Provided is a diversity method using an error correcting code. The diversity method includes: creating a mother code by start performing error correction coding on an input bit string to be coded; puncturing the created mother code and acquiring an error correcting code including systematic information and partial parity information; and space-time encoding the acquired error correcting code corresponding to each frequency.