Electronics and Telecommunications Research Institute

Yonsei University

Industry-University Cooperation Foundation Hanyang University

Dae Ig Chang

Ho Jin Lee

Pan Soo Kim

In Ki Lee

Kwang Deok Seo

Hyun Ha Hong

Min Su Shin

Won Sup Chi

Dong Jun Lee

Tae Hoon Kim

Deock Gil Oh

Nae Soo Kim

Joon Gyu Ryu

Dongweon Yoon

Eun A Choi

Mankyu Park

Nam Kyung Lee

Jae Hee Han

Jaeyoon Lee

Jang Hee Kang

Nam Young Kim

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.

Apparatus and method for accessing star network/mesh network of time division multiple access (TDMA)/single channel per carrier (SCPC) integrated satellite communication

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.

Source-channel combined coding method and satellite broadcasting system using the same

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.

Dual mode satellite very small aperture terminal apparatus and controlling method thereof

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. Therefore, all the networks can be effectively used in extreme circumstances.

Method and apparatus for routing in wireless network

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 &#x3b8; while giving priority to a symbol having a small signal size when the size of &#x3b8; 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.

Bits-to-symbol mapping method for 4+12+16 APSK modulation

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.

Method and system for fast layer 3 hand-over

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.

Terminal transmission apparatus for providing multimedia service via satellite communication link and method for providing multimedia service using the same

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.

MPE-FEC RS decoder and decoding method thereof

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.

Apparatus for mobile satellite communications and method of controlling communications route

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.

Method for generating and processing hierarchical PES packet for digital satellite broadcasting based on SVC video

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.

Method and system for effective adaptive coding and modulation in satellite communication system

An apparatus for resolution of phase ambiguity is disclosed. The apparatus receives a modulated signal and resolves a phase ambiguity of the modulated signal while recovering the modulated signal to original data, wherein the apparatus includes a phase ambiguity detector for receiving demodulated data and frame synchronization information, and detecting a phase ambiguity value from the demodulated data based on a frame synchronization information; a phase ambiguity eliminator for receiving the phase ambiguity value and the demodulated data, and generating a phase ambiguity eliminated data by inverting the phase ambiguity value and multiplying the inverted phase ambiguity value and the demodulated data. The present invention can resolve a phase ambiguity occurred in various modulation modes including a burst mode communication with the same algorithm so it can effectively be implemented to an adaptive MODEM.

Growing community of inventors

Daejeon, South Korea

Dae Ig Chang