Abstract: An operation method of a satellite in a non-terrestrial network may comprise: determining a frequency resource allocation order for allocating frequency resources to beams in consideration of a frequency band of a terrestrial system and degrees of interference to the terrestrial system; configuring a minimum performance condition for maintaining a service of the non-terrestrial network, the minimum performance condition being applied to each of the beams; configuring an operating condition of a multi-agent deep reinforcement learning for each beam controller of the satellite; and controlling the each beam controller to sequentially allocate the frequency resources to a managed beam according to the frequency resource allocation order while considering the minimum performance condition.

Abstract: An oil adsorbent is manufactured by including performing heat treatment on a non-woven fabric for low-temperature carbonization, and has the effect of adsorbing and evaporating oil having various carbon numbers ranging from a low boiling point to a high boiling point to remove the oil, has photothermal conversion efficiency, high evaporation efficiency of oil by sunlight, and a high adsorption amount and high adsorption rate, thereby making the adsorption-evaporation cycle fast and efficiently performing the adsorption-evaporation, and has an environmentally friendly effect that does not cause any environmental problems even if the oil adsorbent is put into a river, a sea, or the like and then lost.

Abstract: A frequency resource allocation apparatus comprising a processor is configured to select resources for transmitting a signal to a user based on a learning model, allocate the selected resources to the user, transmit the signal to the user using the selected resources, receive information about whether the transmission of the signal is successful or not from the user via a feedback channel after a delayed time, and update an internal parameter of the learning model with respect to the resources used for transmitting the signal.

Abstract: An oil absorbent is manufactured by including performing heat treatment on a non-woven fabric for low-temperature carbonization, and has the effect of adsorbing and evaporating oil having various carbon numbers ranging from a low boiling point to a high boiling point to remove the oil, has photothermal conversion efficiency, high evaporation efficiency of oil by sunlight, and a high adsorption amount and high adsorption rate, thereby making the adsorption-evaporation cycle fast and efficiently performing the adsorption-evaporation, and has an environmentally friendly effect that does not cause any environmental problems even if the oil absorbent is put into a river, a sea, or the like and then lost.

Abstract: Provided is a communication method for downlink transmission with a low peak to average power ratio (PAPR) and compatibility with long-term evolution (LTE)-based downlink transmission in an LTE-based mobile communication system in which the performance degradation may occur due to a high PAPR in multi-carrier transmission caused by non-linearity of a power amplifier in a base station including a satellite, to have the effects of supporting a terminal that reuses an existing terrestrial LTE chipset and a terminal that enables downlink reception with a low PAPR with no collision between the terminals, and of implementing an integrated satellite/terrestrial mobile communication system with a minimum change of an existing mobile communication system to ensure economic efficiency.

Abstract: A random access method in a mobile communication system, the random access method for supporting random access with a cell size of about 100 kilometers (km) or more and a power limited terminal, and a preamble structure thereof are provided. While a conventional long term evolution (LTE) random access preamble sequence is reused, a difference in a round-trip delay time between terminals in a large cell area may be compensated. Additionally, since higher power transmission is achieved per bandwidth, a higher link margin may be secured. Also, compatibility with resource scheduling of the conventional LTE may be maintained. Random access may be supported in a large cell, and a preamble structure of a satellite mobile communication may be implemented based on terrestrial LTE.

Abstract: Provided is a power control and link adaptation method for compensating for a long round trip delay time and slow channel fading in a long term evolution (LTE)-based mobile communication system having a long round trip delay time, similar to a satellite mobile system, the method that may compensate for the long round trip delay time of the satellite mobile system in which a distance between a base station and a terminal is relatively long, when compared to a terrestrial LTE system, support a modulation and coding scheme (MCS) level requested by a terminal, by predicting a channel after the round trip delay time elapses, maintain compatibility within an existing LTE frame, by generating a transmit power control (TPC) instruction for an uplink closed-loop power control, on a frame by frame basis, and compensate for slow channel fading of the satellite mobile system.

Abstract: The present invention relates to an apparatus and a method of predicting radio interference of a receiver.

Abstract: A transmission apparatus and method for implementing frequency selectivity in a multi-beam satellite system that transmits a signal to user equipment through one or more antenna feed groups. The transmission apparatus includes: an antenna feed group selecting unit configured to select one or more antenna feed groups from the one or more antenna feed groups; a cyclic delay offset determining unit configured to determine a cyclic delay offset according to a determination result of the antenna feed group selecting unit; and a transmitting unit configured to apply the cyclic delay offset determined by the cyclic delay offset determining unit to a signal to be transmitted through the one or more antenna feed groups selected by the antenna feed group selecting unit, and to transmit a resultant signal.

Abstract: First resource blocks of a radio resource each include a first number of subcarriers and a second number of subframes having the first size. In this case, second resource blocks are formed, each second resource block including fewer subcarriers than the first number and fewer subframes than the second number based on the first resource blocks. A signal is transmitted in the first resource block or second resource block, and particularly, signals of first and second channels are transmitted by sharing the first resource block.

Abstract: Disclosed are an apparatus and a method for normally receiving data by accurately estimating and compensating for a frequency offset for a wireless frequency channel through which data are transmitted in a communication system under wireless frequency environment. In the present invention, data transmitted through the wireless frequency channel are received, the frequency offset in the wireless frequency channel from the receive data is estimated based on an interpolation scheme using the periodogram, and the frequency offset is compensated to receive the data by frequency-synchronizing with the wireless frequency channel.

Abstract: In a system that performs mobile communication using at least two beams, by determining a size of a beam based on information that is acquired for mobile terminals attempting an access, a beam of a form having an adaptive size is formed and thus communication is performed. A beam sector including a plurality of beam segments and a beam segment that forms a beam of a minimum size within entire coverage is set, and while forming one beam per beam sector, a size of a beam is adaptively determined.

Abstract: A method in which a satellite or a terrestrial earth station that is included in a satellite communication system that shares a frequency resource with a terrestrial communication system allocates a frequency resource is provided. The satellite divides an area of a first satellite beam into at least one sector. The satellite determines a first sector in which a satellite terminal is located among the at least one sector. The satellite determines a second sector corresponding to the first sector among at least one sector that is included in a first terrestrial cell. The satellite allocates at least one of first frequency resources for the second sector to the satellite terminal. The first terrestrial cell is located within an area of a second satellite beam adjacent to the first satellite beam.

Abstract: A random access method in a mobile communication system, the random access method for supporting random access with a cell size of about 100 kilometers (km) or more and a power limited terminal and a preamble structure thereof are provided. While a conventional long term evolution (LTE) random access preamble sequence is reused, a difference in a round-trip delay time between terminals in a large cell area may be compensated. Additionally, since higher power transmission is achieved per bandwidth, a higher link margin may be secured. Also, compatibility with resource scheduling of the conventional LTE may be maintained. Random access may be supported in a large cell, and a preamble structure of a satellite mobile communication may be implemented based on terrestrial LTE.

Abstract: Provided is a power control and link adaptation method for compensating for a long round trip delay time and slow channel fading in a long term evolution (LTE)-based mobile communication system having a long round trip delay time, similar to a satellite mobile system, the method that may compensate for the long round trip delay time of the satellite mobile system in which a distance between a base station and a terminal is relatively long, when compared to a terrestrial LTE system, support a modulation and coding scheme (MCS) level requested by a terminal, by predicting a channel after the round trip delay time elapses, maintain compatibility within an existing LTE frame, by generating a transmit power control (TPC) instruction for an uplink closed-loop power control, on a frame by frame basis, and compensate for slow channel fading of the satellite mobile system.

Abstract: Provided is a communication method for downlink transmission with a low peak to average power ratio (PAPR) and compatibility with long-term evolution (LTE)-based downlink transmission in an LTE-based mobile communication system in which the performance degradation may occur due to a high PAPR in multi-carrier transmission caused by non-linearity of a power amplifier in a base station including a satellite, to have the effects of supporting a terminal that reuses an existing terrestrial LTE chipset and a terminal that enables downlink reception with a low PAPR with no collision between the terminals, and of implementing an integrated satellite/terrestrial mobile communication system with a minimum change of an existing mobile communication system to ensure economic efficiency.

Abstract: A method of forming a beam and a method of allocating a resource in a long term evolution (LTE)-based mobile communication system are provided. More particularly, a method of forming an adaptive satellite multiple beam for enhancing multiple beam performance and a method of allocating a resource that can relieve interference in a beam that is formed according to the method in a multiple beam system in which satellite communication and mobile communication is coupled based on LTE are provided. When providing a communication service that supports both satellite communication and ground communication, performance degradation can be reduced with the same interface, and by providing a method of forming an adaptive beam and a method of allocating a resource by relieving interference of the formed beam in consideration of a position of the terminal by independently allocating a subcarrier to the terminal and enabling the terminal to process the subcarrier, performance of a multiple beam can be improved.

Abstract: A method of designing and communicating a beam in a communication system is provided. More particularly, a method of designing and communicating a beam in a communication system using carrier aggregation in order to increase a maximum data rate in a multiple beam mobile communication system is provided. By applying carrier aggregation, a maximum data rate can be improved.

Abstract: A signal processing technology for allowing a repeater to transmit a signal received from an external apparatus to a terminal is provided. In a satellite system, a signal transmitted from a satellite or transmitted to a satellite is subject to a low order modulation, and a terrestrial repeater performs a high order modulation on signals and retransmits the signals.

Abstract: Disclosed are an apparatus and a method for normally receiving data by accurately estimating and compensating for a frequency offset for a wireless frequency channel through which data are transmitted in a communication system under wireless frequency environment. In the present invention, data transmitted through the wireless frequency channel are received, the frequency offset in the wireless frequency channel from the receive data is estimated based on an interpolation scheme using the periodogram, and the frequency offset is compensated to receive the data by frequency-synchronizing with the wireless frequency channel.