Abstract:
An operation method of a terminal in a communication system may comprise: receiving, from a satellite, transmission timing information including information on a first transmission timing of a first SSB of each of at least one local cell and information on second transmission timings of second SSBs of sub-cells belonging to each of the at least one local cell; identifying the first transmission timing of the first SSB and the second transmission timings of the second SSBs based on the transmission timing information; attempting to receive the second SSBs when the first SSB is received at the first transmission timing; acquiring cell access information from the second SSBs by receiving the second SSBs; and accessing the satellite by using the acquired cell access information.
Abstract:
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.
Abstract:
A method for overcoming rain attenuation in a return link in a satellite communication system is provided. The method may include periodically receiving channel state information from a terminal, estimating a signal-to-noise ratio (SNR) based on the channel state information, determining, based on the estimated SNR, whether rain attenuation is to be compensated for, analyzing the channel state information and determining a rain attenuation compensation scheme, and transmitting an operating mode change command corresponding to the rain attenuation compensation scheme to the terminal.
Abstract:
The present invention relates to a method for transmitting a synchronization signal block (SSB) through a plurality of satellites from a base station that can connect to a plurality of gateways, wherein the method may comprise the steps of: controlling transmission of first SSBs corresponding to the number of beams of each satellite through respective transmission beams in a first SSB cycle; determining a transmission beam of each of the satellites on the basis of a first measurement report for the respective beams received from a terminal; and controlling transmission of second SSBs for determining one combination including two or more gateways among the plurality of gateways in a second SSB cycle.
Abstract:
A transmission device in a satellite IoT system may comprise: a CRC value generator that receives first data and generates and outputs a payload CRC value; a forward error correction encoder that receives second data consisting of the first data and the payload CRC value from the CRC value generator, and performs forward error correction coding on the second data; an interleaver that receives third data consisting of the forward error correction coded first data and the payload CRC value from the forward error correction encoder, and outputs interleaved payload blocks by performing cyclic shifts on the forward error correction coded first data based on offsets; and a frequency hopping unit that receives the interleaved payload blocks from the interleaver, and generates and transmits payload blocks frequency-hopped according to a hopping sequence.
Abstract:
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′.
Abstract:
Provided are a phase locked loop (PLL) apparatus and an operating method of the PLL apparatus including a PLL unit to provide a fixed frequency signal, a converter to convert, using the fixed frequency signal, a frequency of a first signal oscillated by a first voltage-controlled oscillator (VCO) based on a first control voltage, a first frequency divider to divide the converted frequency of the first signal, and a first phase comparator to compare the divided frequency of the first signal to an input first reference frequency and detect a first phase difference, wherein the first VCO may adjust the first control voltage based on the detected first phase difference to equalize the divided frequency of the first signal to the first reference frequency.
Abstract:
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.
Abstract:
According to an aspect of the present disclosure, there is provided a method of controlling a power amplifier in a low-orbit satellite network, the method comprising: communicating, by a terminal, with a satellite; setting an initial applied voltage and frequency; receiving orbit information from the satellite; and updating the initial applied voltage according to the orbit information and network environment.
Abstract:
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.