Abstract: There are provided an apparatus and a method for establishing a contention window in a WiMedia wireless network. The contention window establishing apparatus includes: a parsing unit extracting the number of devices that intend to transmit data from a beacon received during a beacon period and an access category (AC) of each device; a calculation unit calculating a transmission probability of each access category (AC) on the basis of the extracted number of devices; and a contention window establishing unit establishing a contention window for each access category (AC) on the basis of the calculated transmission probability, to reduce contentions among the devices and decrease data transmission latency time, thereby maximizing efficiency in data transmission latency time.

Abstract: There are provided a terminal capable of selecting a suitable wireless module among a plurality of wireless modules depending on a situation and providing an optimal image even in a state in which a display unit is separated from a main body by performing wireless communication, and a wireless communication method thereof. To enable this, the terminal includes a main body generating and transmitting image data in response to an external input; a display unit mountable on or demountable from the main body, receiving the image data from the main body and displaying an image corresponding to the image data; and a wireless communication unit provided in each of the main body and the display unit, switching a wireless communication frequency band on the basis of a transmission rate of the image data and transmitting the image data to the display unit.

Abstract: A media access control method in a wireless network is provided. Each of devices in the wireless network determines one of a plurality of beacon slots within a beacon period as a beacon slot of the device. The devices in the wireless network determine a data transmission order in accordance with the slot numbers of the beacon slots of the devices in a reserved period of a data transmission period. Data is transmitted in the unreserved period in accordance with the determined data transmission order.

Abstract: A beamforming apparatus for a multi-antenna system includes a phase control unit including a plurality of phase shifters which respectively control the phases of signals according to a preset phase weight vector; a signal combination unit combining the signals outputted from the plurality of phase shifters; a frequency down converter down-converting the combined signal outputted from the signal combination unit into a baseband signal; an analog/digital (A/D) converter converting the baseband signal into a digital signal; and a radio frequency (RF) beamforming control unit providing a plurality of preset phase weight vectors to the phase control unit according to a preset application sequence, deciding a maximum signal-to-noise ratio (SNR) among a plurality of SNRs corresponding to the applied phase weight vectors by using the digital signal outputted from the A/D converter, and controlling the beamforming of the phase control unit by using the maximum SNR.

Abstract: A cooperative transmission method includes: a first operation of coding, by a source node, a message desired to be transmitted according to a first encoding scheme to generate a first codeword and transmitting the first codeword to a relay node and a destination node; a second operation of decoding, by the relay node, the first codeword which has been received from the source node, coding the decoded message according to a second coding scheme to generate a second codeword, coding a part corresponding to parity of the second codeword according to the first coding scheme to generate a third codeword, and transmitting the third codeword to the destination node; and a third operation of decoding, by the destination node, the first codeword which has been received from the source node and the third codeword which has been received from the relay node, combining the message generated by decoding the first codeword and the parity part of the second codeword generated by decoding the third codeword to generate a fou

Abstract: A beamforming apparatus for a multi-antenna system includes a phase control unit including a plurality of phase shifters which respectively control the phases of signals according to a preset phase weight vector; a signal combination unit combining the signals outputted from the plurality of phase shifters; a frequency down converter down-converting the combined signal outputted from the signal combination unit into a baseband signal; an analog/digital (A/D) converter converting the baseband signal into a digital signal; and a radio frequency (RF) beamforming control unit providing a plurality of preset phase weight vectors to the phase control unit according to a preset application sequence, deciding a maximum signal-to-noise ratio (SNR) among a plurality of SNRs corresponding to the applied phase weight vectors by using the digital signal outputted from the A/D converter, and controlling the beamforming of the phase control unit by using the maximum SNR.

Abstract: A multi-antenna system using adaptive beamforming includes a phase shift unit, a signal combination unit, a frequency down-converter, and an analog-to-digital (A/D) converter, and a beamforming control unit. The phase shift unit includes a plurality of phase shifters which shift the phases of signals received from a plurality of antennas. The signal combination unit combines phase-shifted signals output from the plurality of phase shifters. The frequency down-converter down-converts a signal output from the signal combination unit into a baseband signal. The A/D converter converts the baseband signal into a digital signal. The beamforming control unit searches for a weight vector higher than a preset threshold signal-to-noise ratio (SNR) when a reception SNR of the digital signal output from the A/D converter is lower than the threshold SNR, and changes a currently set weight vector into the searched weight vector to provide to the phase shift unit.