Abstract: Disclosed is a star network/mesh network accessing method and apparatus of a terminal in a satellite communication system, the method including receiving time slot resources from a central station and operating in a time division multiple access (TDMA) start network communication mode between the central station and a terminal, transferring, to the central station, a TDMA mesh network connection request message for a destination terminal, receiving traffic burst time plan (TBTP) information corresponding to the TDMA mesh network connection request message from the central station and operating in a TDMA mesh network communication mode between terminals, and switching from the TDMA mesh network communication mode between the terminals to a single channel per carrier (SCPC) mesh network communication mode between the terminals when Voice over Internet Protocol (VoIP) traffic is greater than a threshold.

Abstract: Disclosed is a communication method and apparatus without side information (SI) using a cross-correlation. The communication method may include obtaining a reception pilot signal from a reception signal, and detecting a phase sequence used for a transmission signal based on the reception pilot signal.

Abstract: Disclosed is a star network/mesh network accessing method and apparatus of a terminal in a satellite communication system, the method including receiving time slot resources from a central station and operating in a time division multiple access (TDMA) start network communication mode between the central station and a terminal, transferring, to the central station, a TDMA mesh network connection request message for a destination terminal, receiving traffic burst time plan (TBTP) information corresponding to the TDMA mesh network connection request message from the central station and operating in a TDMA mesh network communication mode between terminals, and switching from the TDMA mesh network communication mode between the terminals to a single channel per carrier (SCPC) mesh network communication mode between the terminals when Voice over Internet Protocol (VoIP) traffic is greater than a threshold.

Abstract: A communication apparatus of an earth station to avoid frequency interference with a terrestrial communication system is provided. The communication apparatus may include a signal extractor configured to acquire a signal of a terrestrial radio station by cancelling a signal transmitted by the earth station from received signals, a detector configured to detect an interference state between a satellite communication network and a terrestrial communication network by comparing a signal strength of the signal of the terrestrial radio station to a predetermined interference signal threshold, and a frequency allocator configured to allocate a new frequency slot to be used by the earth station to transmit a signal, when the detector detects the interference state.

Abstract: A phase locked loop includes: a loop filter; a voltage controlled oscillating unit configured to output a frequency varying according to an output voltage of the loop filter; a frequency down-converting unit configured to down-convert an output frequency of the voltage controlled oscillating unit according to a band of the output frequency of the voltage controlled oscillating unit; and a frequency divider configured to divide a frequency down-converted by the frequency down-converting unit. The output frequency of the voltage controlled oscillating unit varies according to the output voltage of the loop filter and a control signal compensating the frequency down-converted by the frequency down-converting unit.

Abstract: A source-channel combined coding method including: determining whether a channel signal-to-noise ratio (SNR) is varied or not; when it is determined that the channel SNR is varied, selecting a MODCOD suitable for the channel SNR by referring to a first table defining an SNR threshold value at which data transmission is performed without an error, for each MODCOD designating a low density parity check (LDPC) code rate and a modulation scheme; calculating a source coding rate by using an effective information bit rate of the selected MODCOD; extracting network abstraction layer (NAL) units for each layer from an inputted video frame so as to satisfy the calculated source coding rate, and packetizing the extracted NAL units; binding packets to configure a baseband (BB) frame; and LDPC coding and modulating the BB frame through the code rate and the modulation scheme which are designated by the selected MODCOD.

Abstract: Provided are a satellite VSAT apparatus and a control method thereof. The satellite VSAT apparatus according to an exemplary embodiment of the present invention can switch a modulation type of a signal to be transmitted from an indoor unit (IDU) to the outdoor unit to a linear or non-linear type in a case in which outputting of a transmitted signal is not controlled to an outdoor unit due to limitations, that is, there is no function such as an automatic signal level control in a block up-converter (BUC), a case in which transmission output limitation is large due to a lot of interference requirements for an adjacent channel, a case in which the number of adjacent channels (carriers) is large, or a case in which adjacent channel interference is large due to a frequency in a satellite multi-beam environment and polarization reuse, in a satellite VSAT apparatus system which aims at a low-priced user terminal.

Abstract: A method of routing a wireless network is provided. The method is performed by each of a group of nodes and includes: receiving a routing request signal; determining whether a node itself is a destination node, by referring to a traffic distribution table showing traffic throughput of the group of nodes and an intermediate-node weight table showing weights of intermediate nodes on all paths between the group of nodes and a source node, wherein a route path is selected by referring to the weights of intermediate nodes; and when it is determined that the node itself is the destination node transmitting a routing response signal to the source node that has transmitted the routing request signal, and receiving a packet from the source node, wherein the transmitting and receiving are performed by the determined destination node. By using the method, traffic in wireless network extreme communications can be distributed at intermediate nodes as well as at destination nodes.

Abstract: Disclosed is a bits-to-symbol mapping method of 4+12+16 amplitude phase shift keying (APSK) having excellent performance against the non-linearity of a high power amplifier. According to the present invention A bits-to-symbol mapping method of 4+12+16 APSK modulation, comprising: representing 32 symbols of the 4+12+16 APSK modulation by a polar coordinate and arranging the 32 symbols by a size of ? while giving priority to a symbol having a small signal size when the size of ? of two or more symbols are same; grouping the arranged 32 symbols into 4 groups according to quadrant regions where the symbols are located; and allocating bits so that the same bits are allocated to the symbols belonging to the same region for each region with respect to each of the first to fifth bits of the symbols grouped into four regions.

Abstract: The present invention relates to a method of seamlessly providing a satellite multimedia Internet service to a fixed subscriber belonging to a lower user network even in a satellite shadow environment and shortening a hand-over processing time between heterogeneous networks by applying a fast layer 3 hand-over technology between satellite and wireless networks in a mobile satellite terminal device.

Abstract: Provided is a method for detecting frame sync and frame structure in a satellite broadcasting system, which acquires an estimated value for detecting frame structure and frame sync and overcomes distortion of correlation analysis values by summing differential correlation values for SOF positions in consideration of the variable frame length, and selecting a maximum value in a channel environment with low signal-to-noise ratio and high frequency error. SOF is a sync word indicating the start point of a frame. The method includes the steps of: acquiring SOF differential correlation value sequences; acquiring sums (di,t) of the correlation values normalized for SOF positions based on the number of symbols per frame by using the above-generated SOF differential correlation value sequences; and selecting a maximum value (dz,x) among the sums of correlation values, detecting z as a frame sync position, and detecting x as a frame structure index.

Abstract: Disclosed is a phase error estimating an apparatus and a method which provides improved convergence speed and tracking speed even in mobile channel environment by variably applying the step size for phase error estimation according to channel status. The apparatus for estimating a phase error includes: a posterior probability (APP) average calculating unit for calculating an APP average value from a soft decision result of a currently received symbol; a step size determining unit for determining a step size variably according to channel status; and a phase error estimating unit for estimating a phase error of the currently received symbol from a phase error of a previously received symbol and the APP average value by using the variably determined step size.

Abstract: The present invention separates inputted triple play IP data into Internet and TV data and voice (VoIP) data, encodes the Internet and TV data permitting a long delay time according to the existing DVB-S2 standard, and encodes the voice data permitting only a short delay time according to a DVB-RCS+M standard based 4K mode. Each encoded data is subjected to the orthogonal modulation and the orthogonally modulated voice data is subjected to a direct sequence spectrum spread according to a spreading factor. The spread spectrum signal is multiplexed in a SCPC frequency division multiple access (FDMA) scheme so as to overlap with frequencies allocated to each user.

Abstract: A decoding method of an MPE-FEC (MultiProtocol Encapsulation-Forward Error Correction) RS (Reed-Solomon) decoder, includes: substituting a value corresponding to an erasure error position with 0 in a reception signal; calculating a syndrome by using the reception signal; calculating an erasure position polynomial by using erasure information; calculating a modified syndrome by using the syndrome and the erasure position polynomial; calculating an erasure error size polynomial by using the modified syndrome; calculating an error position by using the erasure position polynomial; calculating an error size by using a modified Forney's algorithm; and correcting an error through the error position and the error size.

Abstract: A mobile satellite transmission/reception apparatus and a communications route control method using the same are disclosed. The mobile satellite transmission/reception apparatus comprises: a first antenna unit configured to receive a signal along a first communications route; a second antenna unit configured to receive a signal along a second communications route; and a data processor configured to compare cyclic redundancy check (CRC) values with respect to packet streams of signals respectively received by the first and second antenna units, and change communications route to one of the first and second communications routes if packets having the same CRC value are detected.

Abstract: Provided is a decoding apparatus and method based on a variable error correction value. The decoding method includes setting an initial normalized factor and a normalized factor correction value, initially updating a check node based on the initial normalized factor, and updating the check node based on a variable error correction value acquired by adding the initial normalized factor and the normalized factor correction value.

Abstract: A method for generating and processing a hierarchical packetized elementary stream (PES) packet for digital satellite broadcasting based on SVC (Scalable Video Coding) video is disclosed. That is, when SVC video is applied to a digital satellite broadcasting system, a transmitter side can generate a hierarchical PES packet in consideration of a hierarchical structure of SVC video and a receiver side can effectively process a received hierarchical PES packet.

Abstract: Provided are an apparatus for controlling handover between heterogeneous networks, a method of performing handover between heterogeneous networks in a mobile router, and a mobile router. The method includes determining whether a handover to a network employing a different method from a network to which the mobile router belongs is required based on information prestored in the mobile router, the network to which the mobile router belongs determined by current location information of the mobile router and performing the handover according to the result of the determination. Mobility detection time can be reduced by applying the handover technique between wireless/satellite networks based on link trigger and location to a mobile router moving at high speed. Thus, service interruption can be prevented regardless of movement speed, even in a satellite shadow region such as a station.

Abstract: A Second Generation Digital Video Broadcasting via Satellite (DVB-S2) system is provided. More particularly, a method and apparatus for maintaining synchronization of a signal by changing an Adaptive Coding and Modulation (ACM) method that is used for a conventional DVB-S2 system are provided. In the apparatus and method, an FEC frame of a variable length is formed by turbo encoding rather than Bose-Chaudhuri-Hocquenghem (BCH) and Low Density Parity Check (LDPC) encoding, and a Physical Layer (PL) frame of a specific length is formed regardless of a modulation method, so that a satellite terminal receives a signal transmitted at a specific length regardless of a modulation method or a coding rate to easily maintain synchronization without interruption and efficiently transmit the signal.

Abstract: Disclosed is an adaptive multimedia decoding device and method for scalable satellite broadcasting. A TS decoder TS-decodes a first transmission stream and a second transmission stream received through different transmission bands to generate a first video stream, a second video stream, and an audio stream. A first decoder and a second decoder are configured of a plurality of operation modules that are sequentially performed so as to decode the first video stream, the second video stream, and the audio stream and are independently controlled and are operated in parallel. A controller compares the amount of data corresponding to one input unit of the first video stream and the second video stream input to each of the first decoder and the second decoder, to selectively perform each operation module configuring the first decoder and the second decoder whenever the data corresponding to one input unit are input.