Abstract: Provided is a method for handover between heterogeneous networks using a link trigger signal in a multi-interface mobile router. The method includes: maintaining a state of a second network access interface in a sleep state, activating a first network access interface, receiving and transmitting the first network service to a subordinate node in the mobile router located in a first network; when the mobile router senses a second network link-up trigger signal while moving to the second network, changing the state of the second network access interface into an active state and performing handover; and receiving a second network service through the activated second network access interface in the mobile router performing the handover and transmitting the second network service to the subordinate node.

Abstract: Provided is a correlation scheme selecting apparatus and method that can acquire initial synchronization efficiently by calculating frequency error criterion threshold between correlation schemes and selecting a correlation scheme for each region when a correlation value is calculated for initial sync in a communication system with carrier frequency errors. The method for selecting a correlation scheme based on a carrier frequency error includes: calculating mis-detection probability values based on a normalized frequency offset for each correlation scheme; determining as a frequency-error criterion threshold a crossing point of graphs of the calculated mis-detection probability values for each correlation scheme; and selecting a correlation scheme based on the determined frequency-error criterion threshold.

Abstract: Provided is a low-density parity-check (LDPC) decoding apparatus and method using a type-classified index. The apparatus includes: a memory allocating unit for multiplying reception data by an estimated channel value and storing a multiplied value in a memory including a plurality of memory block; an index storing unit for storing a Read Only Memory (ROM) index, an address index and a permutation index for the stored data; a check node updating unit for bring the stored data in parallel based on the ROM index, the address index, and the permutation index and updating a check node; and a bit node updating unit for updating a bit node based on the data stored in the memory and check node information updated in the check node updating unit.

Abstract: Provided are an apparatus and method for generating a soft bit metric and a multi-level (M-ary) Quadrature Amplitude Modulation (QAM) receiving system using the same. The apparatus includes an analog to digital converter for converting an analog symbol signal of a demodulated I (Inphase) or Q (Quadrature) channel into a digital signal, a scaler for scaling the converted digital signal based on a reference value used for determining a space between symbols, a positive integer converter for calculating a positive integer of the scaled digital I or Q channel symbol signal, a sign determinator for determining a sign of the scaled digital I or Q channel symbol signal, and a bit information converter for converting the scaled digital I or Q channel symbol signal into soft bit metric information per bit on the basis of the calculated positive integer and the determined sign value.

Abstract: Provided is a method for detecting frame sync and frame structure in a satellite broadcasting system. The method for detecting frame sync and frame structure includes the steps of: calculating differential correlation values of reception symbols; generating index sequences of reception symbols whose differential correlation values calculated above exceed a threshold value; calculating positions estimated as frame start points which correspond to a total frame number based on the number of symbols per frame for each frame structure; and detecting frame sync and frame structure based on the umber of positions where the above-calculated frame start point estimated positions and the above-generated index sequences are matched.

Abstract: Provided is an apparatus and method for transmitting/receiving multiband broadcasting using scalable video coding, which can solve a limitation of a transmission band in a multichannel satellite broadcasting service and increase availability of a satellite broadcasting service by scalably encoding video data and transmitting the data using a different transmission band for each layer. The apparatus for transmitting multiband broadcasting using scalable video coding includes: a scalable video encoder for scalably encoding video data to generate a scalable video stream having multiple layers; a multiplexer for multiplexing the scalable video elementary stream having multiple layers, a compressed audio elementary stream, and program specification information to generate a transport stream (TS); and a multiband transmitter for separating packets of the TS into multiple TSs according to pre-given priority information and transmitting the packet streams using a different transmission band.

Abstract: Provided are a preprocessing apparatus and a method thereof for group-based decoding. The preprocessing apparatus includes a log likelihood ratio (LLR) calculator for calculating LLRs of received signals, a signal sorter for sorting the received signals based on the calculated LLRs; and a grouping unit for grouping the sorted signals.

Abstract: Provided are repetition apparatus and method for repeatedly transmitting and receiving a data packet using different puncturing patterns to overcome signal attenuation and fading in a high speed mobile environment by repeatedly transmitting the duplicated information bit sequences with parity bits having a different puncturing pattern after channel-encoding the duplicated information bit. The repetition apparatus for repeatedly transmitting a data packet, includes a dual data generator for generating duplicated information bit sequences identical to each of information bit sequences to transmit, a channel encoder for dividing each of the duplicated information bit sequences into a plurality of information bits, and generating coded data packets alternately having a plurality of parity bits according to different puncturing patterns for each of the divided information bits, and a transmitter for transmitting the generated coded data packets sequentially.

Abstract: Provided are an apparatus and method for deciding a transmission format using a variable frame length and a decoding method using the same. The apparatus for deciding the transmission format using the variable frame length includes: a frame synchronization acquiring unit for acquiring a frame synchronization of a received transmission frame; a correlation analyzing unit for performing a correlation analysis with respect to the transmission frame whose synchronization is acquired, considering frame lengths of respective frame structures; and a transmission frame structure deciding unit for deciding the structure of the received transmission frame using the analyzed correlation. Accordingly, a physical layer signaling code (PLSC) demodulation and decoding performance can be enhanced by determining the structure of the transmitted frame without carrying out a PLSC decoding in such a state that a frequency synchronization is not acquired.

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: Disclosed is a demapping method of a soft-decision of an efficient soft determining scheme which is applicable to a DVB-2 satellite communication system. The soft-decision demapping method for a digital signal received through a transmission channel in a communication system using a phase shift keying (PSK) scheme includes: selecting reference symbols in an area having a higher probability than a predetermined probability that the received signal will be positioned among all reference symbols on a constellation diagram using a most significant bit (MSB) value of the received signal; and acquiring a maximum value of a log likelihood ratio (LLR) for the selected reference symbols.

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: There are provided a method for reducing a packet ordering time of layer 3 handover and a mobile satellite terminal using the same. The method for reducing a packet ordering time of layer 3 handover of a mobile router in a home agent of a satellite network connected with the mobile router includes: transmitting a first packet and a second packet to the mobile router through a satellite link of the mobile router; transmitting a sequence control packet to the mobile router through the satellite link; and transmitting a third packet to the mobile router via a wireless link of the mobile router. The sequence control packet provides a reference time for rapidly reordering the second and third packets which reach the mobile router in a reverse sequence.

Abstract: The present invention relates to a transmitting method, a receiving method, a transmitter, and a receiver of a communication system. A transmitting method according to an aspect of the present invention includes generating a burst by scattering a plurality of pilot symbols, and transmitting the burst.

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: 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: 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: Provided is a satellite network communication system based on Second Generation Digital Video Broad-casting via Satellite (DVB-S2). A method for encapsulating transmission data in a digital satellite communication system includes: determining whether a time at which a reference time information packet has to be inserted into a packet data unit is arrived, in the digital satellite communication system; and if the time at which the reference time information packet has to be inserted into the packet data unit is arrived, transforming the packet data unit in the form of a baseband data packet including the reference time information packet. Therefore, by allowing transmission of Network Clock Reference (NCR) information in a satellite communication environment based on Generic Steam Encapsulation (GSE), bidirectional satellite communications are possible.

Abstract: Provided is a correlation apparatus and method for acquiring a robust synchronization. The correlation method may include: calculating a received symbol phase difference with respect to a received symbol; calculating a correlation SoF symbol phase difference with respect to a correlation SoF symbol for a correlation; calculating a differential correlation value of the received symbol using the received symbol phase difference and the correlation SoF symbol phase difference; calculating a Euclidean distance value of the received symbol using the received symbol phase difference; and calculating a sum correlation value of the received symbol using the differential correlation value and the Euclidean distance value.

Abstract: A method of reconstructing reference time information of a transmission frame in a digital satellite communication system is provided, including: receiving the transmission frame including reference time information; recording receiving time of start of frames of the plurality of physical layer frames included in the transmission frame; determining receiving time of a start of frame corresponding to the physical layer frames including the reference time information based on the recorded information when the physical layer frame including the reference time information is received; and reconstructing the reference time information based on the determined receiving time information of the start of frame. Network synchronization is stably acquired and maintained during two-way communication even in the satellite communication network environment.