Electronics and Telecommunications Research Institute

Kun Seok Kang

Ho Jin Lee

Hee Wook Kim

Do Seob Ahn

Bon Jun Ku

Do-Seob Ahn

Tae Chul Hong

Soo Young Kim

Seung Hyun Nam

Yeon Su Kang

Kwonhue Chol

In a satellite and terrestrial integrated communication system in which a satellite communication system and a terrestrial communication system share and use an identical frequency band, an interference to a mobile earth station (MES) of the satellite communication system using an identical frequency by an uplink signal transmitted to a base station of the terrestrial communication system by a user equipment (UE) may be mitigated. When a communication of the MES is requested, a satellite communication apparatus to perform resource block (RB) allocation for a satellite communication in the satellite and terrestrial integrated system may include a controller configured to allocate a first RB to the MES, and a communicator configured to transmit a use notification of the first RB to at least one terrestrial base station located in an interference range of an uplink signal of the MES.

Apparatus and method for uplink power control of satellite and terrestrial integrated communication system

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.

Method for enhanced uplink transmission having low PAPR in LTE-based mobile communication system

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.

Random access method and random access channel structure in mobile communication system having large cell radius

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.

Methods for power control and link adapation in LTE-based mobile communication system

Disclosed is a communication method of a satellite mobile communication system. The communication method of a satellite mobile communication system, includes: receiving system information indicating frame intervals in which first user equipments using a satellite radio interface in commonality with a terrestrial radio interface do not perform communications from a base station; accessing the base station in the rest frame intervals other than frame intervals in which the first user equipments do not perform communications, based on the system information; transmitting the system information from the base station to second user equipments using a satellite radio interface optimized for satellite environment; and accessing the base station in the rest frame intervals based on the system information received in the second user equipments.

Satellite mobile communication systems considering evolution of satellite mobile communication services market and method for communication using the 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

A method and mobile communication terminal for handover in a mobile communication network including at least one mobile communication base station and a communication satellite. The handover method includes the steps of: (a) calculating a signal power received from a currently communicating mobile communication base station among the at least one mobile communication base station, (b) calculating a signal power received from each of the communication satellite and the at least one mobile communication base station except the base station of step (a), (c) selecting a mobile communication base station having the highest among the calculated signal powers except the signal power received from the communication satellite and the signal power received from the base station of step (a), and (d) when the signal power calculated in step (a) is below a predetermined minimum handover power, a difference between the signal power of the selected mobile communication base station and the signal power calculated in step (a) is equal to or below a first terrestrial handover sensitivity, and there is no other mobile communication base station capable of communicating with the mobile communication terminal, performing handover to the communication satellite.

Method and apparatus for handover in mobile communication network including satellite network

A method for optimizing phase factors in partial transmit sequence orthogonal frequency division multiplexing system. The method includes initializing sub-block signals by applying an initial phase factor to the sub-block signals in all sub-blocks; setting a reference peak value with a peak value of a signal formed by combining the sub-block signals; selecting a phase value that minimizes the peak value of an output signal as the phase factor of each sub-block by applying a next phase value to each sub-block signal as the phase factor, and repeating this with respect to the remaining available phase values.

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Daejeon, South Korea

Kun Seok Kang