Abstract: A communication method of a macro base station, a macro terminal, a micro base station, and a micro terminal determines an interference control scheme for each interference condition between a micro cell and a micro cell and between a macro cell and a micro cell in a hierarchical cellular network, and controls interference in the hierarchical cellular network where a detailed operation for each determined interference control scheme, a message associated with the detailed operation, and a resource management scheme are defined.

Abstract: Provided is a method and apparatus for determining a downlink beamforming vector in a hierarchical cell communication system. Small base stations may determine transmit beamforming vectors of the small base stations so that interference from the small base stations may be reduced in a macro terminal. A macro terminal and small terminals may determine receive beamforming vectors based on the transmit beamforming vectors of the small base stations. A macro base station may determine a transmit beamforming vector based on effective channels to terminals using the receive beamforming vectors of the terminals.

Abstract: Provided is an interference aligning method and apparatus that does not perform full feed-forwarding in a hierarchical cell communication. A macro base station may generate respective transmission beamforming vectors of macro terminals to null interference channels to pico terminals and to remove interference among the macro terminals. The effective interference channels are based on reception beamforming vectors of the pico terminals. The macro base station may transmit, to a macro terminal, a feed-forward indicator (FFI) indicating a method of transmitting information associated with a reception beamforming vector of the macro terminal. The macro terminal may obtain information associated with the reception beamforming vector based on the FFI.

Abstract: Provided is a method of generating a transmit beamforming vector and a receive beamforming vector to substantially eliminate the effect of interference transmitted from macro terminals to a pico base station in a hierarchical cell environment. Also, provided is a method of selecting, from a plurality of macro terminals, a macro terminal for transmitting data to a macro base station.

Abstract: A communication method of a micro base station for interference control is provided. The communication method includes determining whether to perform a handover of macro user equipment from a macro base station to a micro base station based on interference from the macro user equipment served by the macro base station to micro user equipment served by the micro base station, searching for an index of a resource allocable to the macro user equipment, and transmitting, to the macro base station, a handover request message including the index of the resource allocable to the macro user equipment.

Abstract: A method and apparatus for controlling transmission power in a wireless network area is provided. A target base station may control transmission power in cooperation with a neighboring base station and, thus, a satisfaction with a Quality of Service (QoS) of target terminals may be improved. Additionally, the target base station may determine whether to control the transmission power in cooperation with the neighboring base station, based on a possible improvement in satisfaction with the QoS of the target terminals.

Abstract: Provided is a cognitive inter-cell interference control method and apparatus. Inter-cell interference may be measured based on various methods in order to recognize an interference channel, and an appropriate interference control algorithm may be applied to the interference channel by modeling based on overhead. Accordingly, interference may be controlled.

Abstract: The present invention provides an acid addition salt of Udenafil, a preparation method thereof and a pharmaceutical composition comprising the same. The acid addition salt of Udenafil in which Udenafil is bonded to an organic acid selected from the group consisting of oxalic acid, benzenesulfonic acid, camphorsulfonic acid, cinnamic acid, adipic acid and cyclamic acid, has excellent solubility in an aqueous medium, water stability and crystallinity, thereby being suitably applied for a pharmaceutical composition.

Abstract: Communication methods of a macro base station which collects position information about a mobile micro base station and that is served by the macro base station, predicts a channel between the macro base station and the micro base station, and performs a handover between the macro base station and the micro base station based on a state of the predicted channel is provided.

Abstract: A data transmission system that determines data transmission power using a virtual cell is provided. A base station may receive transmission data from a plurality of cooperative base stations positioned around the base station, and model terminals receiving an interference signal from the base station and the plurality of cooperative base stations into a virtual cell. The base station may calculate the influence of the interference signal transmitted to the terminal, using the virtual cell, and determine a transmission power for a plurality of frequency bands based on the interference signal.

Abstract: A beamforming method and apparatus for using a rate splitting scheme in a multi-cell multi-antenna system, are provided. The multi-cell multi-antenna system determines transmission and reception beamforming vectors, thereby being divided into a plurality of pairs of single input and single output (SISO) interference channels. A rate splitting scheme may be applied to each of the plurality of pairs.

Abstract: Provided is a multi-cell communication system using a rate-splitting scheme and a transmission frame for the multi-cell communication system. The multi-cell communication system may determine whether to perform a rate-splitting based on channel information of a macro base station and a femto base station in a multi-cell environment. The multi-cell communication system may allocate a power or a bandwidth to a message to be transmitted based on the channel information. In the multi-cell environment, a terminal may receive MAP information from a base station and may decode the received MAP information, determining a base station that performs the rate-splitting.

Abstract: A communication system performs an uplink communication and a downlink communication using respective radio resources that at least partially overlap each other in both time and frequency, which may cause interference to occur in at least one downlink terminal due to at least one uplink terminal. The at least one uplink terminal and the at least one downlink terminal may process the interference according to a rate split scheme, an interference control scheme, and the like. Interference occurring between at least one transmit antenna and at least one receive antenna of a base station may be processed according to an echo cancellation scheme and the like.

Abstract: Provided is a data transmission system that may determine a multiple input multiple output dynamic spectrum management (MIMO-DSM) operation mode of a base station based on information associated with a data transmission route and a computational capability of each base station. A terminal may generate feedback information based on a cooperation level between base stations and may transmit the generated feedback information to a serving base station. The serving base station may select terminals that may receive data from among a plurality of terminals through a MIMO-DSM algorithm and a user scheduling based on the feedback information.

Abstract: Provided are a communication apparatus that may generate a precoding matrix including precoding vectors to cancel or align interference existing in a plurality of terminal devices based on location of the terminal devices, and a terminal device that may estimate a channel formed between the terminal device and the communication apparatus to cancel or align interference signals.

Abstract: Each of a first transmitter and a second transmitter uses a rate split scheme. Each of the first transmitter and the second transmitter may transmit at least four sub-messages, and different transmission powers may be allocated to the at least four sub-messages. Also, each of receivers may cooperate with each other, may share sub-messages that act as interferences, and may extract desired messages using the shared sub-messages.

Abstract: A communication method for at least one mobile station that includes a target mobile station that performs a Cooperative Multi-Point (CoMP) communication with at least two base stations, is provided. The communication method includes determining a beamforming vector used by the at least two base stations based on channel vectors and at least one channel matrix such that a signal-to-leakage-plus-noise-ratio (SLNR) for a target antenna from among antennas of a target mobile station is maximized. A Cholesky factorization may be used to determine an optimal beamforming vector with a low complexity.

Abstract: A method of assigning and managing reference signals in a multi-cell environment, and a network device and a terminal for applying the method, are provided. Reference signal patterns may be assigned to multiple femtocells through a long term coordination of a central control unit that is used to control multiple cells.

Abstract: Provided is a method, and an apparatus and communication system to perform the method, of detecting a victim terminal and performing an interference coordination in a multi-cell environment. The multi-cell environment may include a heterogeneous cell environment including a small cell and a macro cell. The method includes determining whether a macro terminal is located within a cell coverage of a small base station, and adjusting the cell coverage according to the determination.

Abstract: A communication method and apparatus for coordinated multi-point (CoMP) transmission, is provided. Sizes of codebooks for a plurality of base stations may be adjusted based on a status of channels between a target terminal and a plurality of base stations. The terminal feeds back, to at least one of the plurality of base stations, channel direction information (CDI) including a number of bits of feedback.