Electronics and Telecommunications Research Institute

Industrial Cooperation Foundation Chonbuk National University

Do-Seob Ahn

Ho Jin Lee

Hee Wook Kim

Bon-Jun Ku

Hee-Wook Kim

Kunseok Kang

Kun-Seok Kang

Ho-Jin Lee

Byung-Su Kang

Yang-Su Kim

Soo-Young Kim

Tae Chul Hong

Kun Seok Kang

Bon Jun Ku

Dae Sub Oh

Tae-Chul Hong

KunSeok Kang

Deock-Gil Oh

Seong-Pal Lee

Jong-Min Park

Sooyoung Kim

Kwon-Hue Choi

Jae-Moung Kim

Seung-Hyun Nam

Sun-Heui Ryoo

Sun-heul Ryoo

Ming-Lu Jin

Yeon Su Kang

Yeonsu Kang

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.

Apparatus and method for providing frequency selectively in satellite communication system

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.

Method for transmitting and receiving uplink signal in wireless communication system

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.

Apparatus and method for receiving data in communication system

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.

Communication method and beam forming apparatus in multi-cell mobile communication system

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.

Signal processing method for terrestrial repeater

In a system where satellite communication using multi-beams is performed for each group including a plurality of beams, a required data transmission rate of each beam is detected for each group, more traffic resources are allocated to a beam having a higher required data transmission rate than other beams based on the detection result, and data traffic transmitted to each beam in the group is adaptively controlled.

Method and apparatus for allocating traffic resources in multi-beam satellite communication system

A diversity method using an error correcting code. The diversity method includes creating a mother code by performing error correction coding on an input bit string to be coded, puncturing the created mother code and acquiring an error correcting code including systematic information and partial parity information, and space-time encoding the acquired error correcting code corresponding to each frequency.

Diversity method using error correcting code

Provided is a satellite communication system for obtaining a diversity gain by transmitting a signal applied with STBC. When a signal transmission band of a link between a satellite and a terminal differs from that of a link between a satellite and a repeater, the satellite communication system includes: a satellite for transmitting a first signal encoded to STBC using a band of a link formed between the satellite to a terminal and transmitting a second signal encoded to STBC using a band of a link formed between the satellite to a repeater; and at least one of frequency transforming repeaters for receiving the second signal through the band of the link formed between the satellite to the repeater, transforming the received second signal to a signal with other frequency band, and transmitting the transformed second signal using a band of a link formed to a terminal.

Signal transmission mechanism with diversity gain in satellite communication network

Provided is a method of establishing an uplink in a mobile satellite communication system, the method including: receiving a random uplink access signal from terminals included in a coverage of a satellite beam; estimating a location of each of the terminals; calculating an uplink transmission point in time when each of the terminals transmits an uplink signal, based on the estimated location of each of the terminals; transmitting, to each of the terminals, the calculated uplink transmission point in time; and receiving the uplink signal from each of the terminals at the calculated uplink transmission point in time.

Method of establishing uplink in mobile satellite communication system

A power controlled adaptive modulation and coding (AMC) scheme in a satellite communications system includes: calculating, by a user terminal, a received signal-to-noise ratio (SNR) through a packet received from a base station; removing a power control level applied to a packet received before the received packet from the calculated received SNR, and deciding the value obtained by decreasing the calculated received SNR by the power control level; deciding an AMC mode based on the decided received SNR; determining whether power control is required, and deciding a required power control magnitude depending on a channel state positioned in the AMC mode range; transmitting the decided AMC mode and the decided power control information to the base station through channel quality indicator (CQI) feedback; and applying the AMC mode based on information received, and increasing a power by a power control magnitude decided from the received information.

Power controlled adaptive modulation and coding scheme in satellite communications system

The present invention relates to a communication method in a mobile communication system. An exemplary embodiment of the present invention provides a mobile satellite communication system having a complementary terrestrial component among various mobile communication systems. The mobile satellite communication system can simultaneously provide a communication service and a broadcasting service to a terminal according to integration between communication and broadcasting. Different signal transmission methods are used between the complementary terrestrial component and a satellite. Specifically, a time division duplex method and a frequency division duplex method are used together and resources are allocated. As a result, system throughput can be increased, and local broadcasting contents can be effectively transmitted to the terminal.

Communication method in mobile communication system

The present invention relates to a system and method of reusing radio resources capable of improving radio resource efficiency. According to an embodiment of the present invention, in a communication system including a repeater that retransmits signals transmitted from a satellite to user terminals, it is possible to reuse some of the radio resources used in a wide area coverage, such as the satellite, in a repeater coverage. Therefore, it is possible to ensure radio resources such that repeater data can be transmitted to user terminals without additional radio resources.

System and method for reusing radio resources

Disclosed is a hierarchical random access method for a wireless communication system having a significantly large cell. According to the present invention, a length of a preamble sequence and a length of a reference slot may be designed based on a terminal having greatest capacity of adjusting a timing error arrived at a base station, and a slot length may be designed to be an integer multiple of the length of the reference slot depending on a timing error correction capacity, thereby enabling terminals to use various slot lengths.

Hierarchical random acces method for wireless communication system having significantly large cell

Provided is a device for tracking polarizations. A receiving polarization tracking device includes a feeder for finding vertical and horizontal vector components by receiving vertical and horizontal polarizations, a polarization estimator for estimating distortion of polarizations using the vertical and horizontal vector components outputted from the feeder, a polarization controller for controlling amplitudes and phases of vertical and horizontal polarizations based on information about the estimated distortion from the polarization estimator and an output signal from the receiving polarization tracking device, and a combiner for combining the vertical and horizontal polarizations controlled from the polarization controller.

Device for tracking polarization

Disclosed is an interaction method between an automatic repeat request (ARQ) and a hybrid automatic repeat request (HARQ) in a system having a long roundtrip delay. A transmission window for the ARQ is operated using inner feedback information from the HARQ, and a waiting window is operated using ARQ status information.

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Daejeon, South Korea

Do-Seob Ahn