Electronics and Telecommunications Research Institute

Joon Gyu Ryu

Deock Gil Oh

Soo Yeob Jung

Pan Soo Kim

Pansoo Kim

Dong Hyun Jung

Jonggyu Oh

Gyeong Rae Im

Dae Ig Chang

Hyun Ha Hong

In Ki Lee

Young Wan Kim

Mankyu Park

Ho Kyom Kim

Sung Min Han

Do Huy Wang

Ki Seop Han

An operation method of an IoT terminal performing communications with a satellite may comprise: receiving a first signal from the satellite; determining a number of symbols constituting a preamble based on the first signal; generating a first frame including a preamble generated according to the determined number of symbols, and transmitting the generated first frame to the satellite; and generating a second frame including a preamble generated according to the determined number of symbols when a response signal to the first frame is received from the satellite, and transmitting the generated second frame to the satellite.

Satellite communication method and apparatus for internet of things communication

A method and an apparatus for network synchronization in a satellite communication system is provided. a satellite station receives a superframe start timing (SST) and an initial counter value from a center station, and receives traffic information sent from a terminal station at a time determined based on the SST. Then, the satellite station generates a compensation value for the SST upon receiving the traffic information, and corrects the SST in accordance with the compensation value.

Method and apparatus for network synchronization in satellite communication system

An ultra-low power data transmission method and apparatus are disclosed. An ultra-low power data transmission method to be performed by a user terminal of an ultra-low power data transmission system includes performing channel coding on a payload included in a transmission packet; interleaving a payload obtained through the channel coding, spreading the interleaved payload using a gold code and an orthogonal variable spreading factor (OVSF), combining a synchronization header spread using the gold code and the OVSF with the spread payload, and modulating a transmission packet in which the payload and the synchronization header are combined.

Ultra-low power data transmission method and apparatus

A method for receiving a wireless signal, performed by a first communication node, may comprise: storing a wireless signal received by the first communication node as samples in a buffer; performing partial correlation operations on the stored samples by a plurality of partial correlators; performing a first FFT operation on results of the partial correlation operations; performing a cumulative product operation on results of the first FFT operation; performing a second FFT operation based on a result of the cumulative product operation; and performing synchronization estimation based on the results of the first FFT operation and a result of the second FFT operation.

Method and apparatus for receiving wireless signal in wireless communication system

Disclosed is a communication method of a satellite and a ground station and apparatuses performing the same. The communication method includes transmitting a plurality of frames to a satellite based on a beam hopping time plan (BHTP) of the satellite and a ground station and synchronizing the BHTP based on an index of a frame received through a beam switching window (BSW) allocated to the ground station among the plurality of frames, and an identification value indicating at least one sub-frame included in the frame.

Communication method of satellite and ground station, and apparatuses performing the same

Disclosed is a communication method performed between a satellite and a ground station and apparatuses performing the communication method. The communication method includes transmitting a plurality of frames based on a beam allocation time schedule (BATS) between a satellite and a ground station, and synchronizing the BATS based on a reception time and a detection time of one or more frames among the plurality of frames to be received through a beam open window (BOW) allocated to the ground station.

Communication method and apparatuses performing the same

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

Disclosed is a network synchronization apparatus and method of a time division multiple access (TDMA)-based mesh network satellite communication system, the network synchronization method of a terminal in a satellite communication system including receiving timing error information from a central station, generating a mesh superframe start time (SST') by reversing a sign of the timing error information, and receiving traffic information transmitted by a transmission terminal using the mesh SST&#x2032;.

Network synchronization apparatus and method of time division multiple access (TDMA)-based mesh network satellite communication system

A satellite communication system and a method of cancelling interference in the satellite communication system are disclosed. The method of cancelling interference in the satellite communication system may include receiving a signal by a central station from a terminal via a satellite transponder, estimating, from the signal, a nonlinear characteristic associated with a central station signal transmitted from the central station, and cancelling an interference signal from the signal using the estimated nonlinear characteristic.

Satellite communication system and method of cancelling interference in the satellite communication system

Provided is an apparatus for an interference signal cancellation of a central station. The apparatus includes: a communication unit; a storage unit configured to store a transmission signal of the central station received via the communication unit; and a signal processor configured to extract first time synchronization information (NCR) of a current time and second time synchronization information (NCR) included in an overlapping signal and calculate a difference value between the two time synchronization information, when the overlapping signal which is an overlapped signal of a terminal station is received on the same channel as a channel of the transmission signal of the central station, and to extract the transmission signal of the central station stored in a previous time in the storage unit based on the difference value and remove an interference signal included in the overlapping signal.

Apparatus and method for interference signal cancellation of central station

Provided is a system and method for synchronization between digital-to-analog converters (DAC) for high speed signal processing. A synchronization method of a multi-DAC apparatus may include: inputting a clock to a multiplexer (MUX) DAC; dividing the clock into a first clock and a second clock; transferring a phase difference between the first clock and the second clock to a D flip-flop; and synchronizing the first clock and the second clock by processing the phase difference.

System and method for synchronization between digital-to-analog converters (DACs) for high speed signal processing

An adaptive coding and modulation (ACM) apparatus and method for a forward link in satellite communication is provided. The ACM apparatus may include a receiving unit to receive a signal-to-noise ratio (SNR) of a received signal, a determination unit to determine whether the SNR of the received signal is less than or equal to a threshold value, and a processing unit to execute a channel prediction algorithm when the SNR of the received signal is determined to be less than or equal to the threshold value.

Adaptive coding and modulation apparatus and method for forward link in satellite communication

Provided are an adaptive coding modulation (ACM)-based simulcast transmission and reception apparatus and method. The apparatus includes a transmitter configured to analyze whether or not it is raining in a region where a receiver is present on the basis of channel state information (CSI) provided by the receiver, encode and/or modulate an image signal according to the analysis result, and provide the encoded and/or modulated image signal through a single band or multiple bands. On the basis of a result of analyzing whether or not it is raining in a region where a receiver is present, it is possible to effectively prevent signal attenuation caused by rain by providing image signals having different resolutions through multiple bands when the region is in a rainfall state.

ACM-based simulcast transmission and reception apparatus and method

Provided are a 3-port orthogonal mode transducer, and a receiver and receiving method using the same. The 3-port orthogonal mode transducer includes: a transmission port having a rectangular shape elongated in a horizontal direction and configured to transmit a Ka-band (30 GHz) vertical polarization signal; a first reception port having a rectangular shape inclined at about +45 degrees at a location being at about +45 degrees with respect to the transmission port and configured to receive a K-band (20 GHz) vertical or horizontal polarization signal phased-delayed about +45 degrees; and a second reception port having a rectangular shape inclined at about &#x2212;45 degrees at a location being at about &#x2212;45 degrees with respect to the transmission port and configured to receive a K-band (20 GHz) vertical or horizontal polarization signal phase-delayed about &#x2212;45 degrees.

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Daejeon, South Korea

Joon Gyu Ryu