Electronics and Telecommunications Research Institute

Kunseok Kang

Do-Seob Ahn

Ho Jin Lee

Hee Wook Kim

Tae Chul Hong

Ho-Jin Lee

Tae-Chul Hong

Yeonsu Kang

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

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

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.

Interaction method between ARQ and HARQ for systems with long roundtrip delay

Provided is a communication method of a mobile terminal in an orthogonal frequency division multiplexing (OFDM) based multi-beam satellite system reusing the same frequency band for all the beams, the method including: receiving location information of the mobile terminal from a satellite to determine a location of the mobile terminal within multiple beams; determining a subcarrier group for a communication with the satellite according to the location of the mobile terminal within the multiple beams; and communicating with the satellite using the subcarrier group for the communication with the satellite.

Satellite, mobile terminal, and complementary terrestrial component in OFDM based multi-beam satellite system reusing the same frequency band for all the beams, and communication method thereof

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Daejeon, South Korea

Kunseok Kang