Abstract: Disclosed are a beam forming method and a multiple antenna system using the same. There is provided a multiple antenna system which forms optimal beam patterns through a transmission of a training sequence between a transmitter and a receiver, each including a plurality of antennas, the multiple antenna system comprising: a transmitter selecting antennas to be activated according to a level and transmitting the training sequence to a receiver through the selected antennas; a receiver selecting the antennas to be activated according to the level and transmitting to the transmitter an index of an optimal transmission weight vector significantly reducing a cost function based on the training sequence transmitted from the transmitter, wherein the transmitter selects antennas so that the beam patterns formed by the antennas selected at a q-th level (q: the index of the level) include the beam patterns formed by the antennas selected at a q+1-th level.

Abstract: Disclosed herein is a wireless power transmission/reception apparatus. The wireless power transmission/reception apparatus includes a wireless power transmission unit configured to generate a wireless power signal to be transmitted, transmit the wireless power signal using magnetic resonance, receive a reflected wireless power signal from a wireless power reception unit, determine whether a load device is present, and transmit a wireless power signal if it is determined that the load device is present in such a way that impedance and output power depending on variation in a distance to the load device are automatically tracked, and wireless power is supplied to the load device in an optimized state. A wireless to power reception unit is connected to the load device, and configured to receive the wireless power signal, provide the wireless power signal to the load device, and reflect a reflected wireless power signal towards the wireless power transmission unit.

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 successive approximation analog/digital converter includes a sample & hold part sampling and holding an intensity of an analog input signal using a single clock cycle of a clock signal; a first comparator comparing the intensity of the analog input signal with comparison voltages determined according to estimated digital values per clock cycle following an operating clock cycle of the sample & hold part; a second comparator comparing the intensity of the analog input signal with a value equal to ½ of a preset reference voltage in the latter half of the operating clock cycle of the sample & hold part; a successive approximation register determining a value of an MSB of a digital value to be converted according to the comparison result of the second comparator and values of bits successive to the MSB according to the comparison result of the first comparator, and generating the estimated digital values by applying estimated values to undetermined bits; and a digital/analog converter generating the

Abstract: Disclosed herein are a wireless power transmission apparatus and a transmission method thereof. The wireless power transmission apparatus is configured to include a wireless power transmitter generating a wireless power signal to be wireless transmitted, wirelessly transmitting the generated wireless power signal by a magnetic resonance manner, receiving a reflection wireless power signal to determine whether or not a load apparatus is presented, and supplying power to the load apparatus; and a wireless power receiver connected to the load apparatus and receiving the transmitted wireless power signal by the magnetic resonance manner and supplying it to the connected load apparatus and reflecting the remaining wireless power signal to the wireless power transmitter, whereby a transmission apparatus can recognize a receiving environment and resonance characteristics are improved, without a separate communication device or a system.

Abstract: A broadband active circuit with a feedback structure includes: an active load unit providing a load varied according to a control voltage; an active circuit unit connected between the active load unit and a ground and outputting a signal corresponding to a pre-set bandwidth, among input signals; and a feedback circuit unit formed between an output terminal of the active circuit unit and the active load unit and providing a signal from the output terminal of the active circuit unit to the active load unit.

Abstract: Disclosed herein is there is provided an apparatus for transmitting and receiving wireless energy using meta-material structures having a negative refractive index. The apparatus includes a wireless energy transmission unit and a wireless energy reception unit. The wireless energy transmission unit generates wireless energy to be wirelessly transmitted, and then wirelessly transmits wireless energy, which is normally propagated radially, using a magnetic resonance method while concentrating the wireless energy at a single point. The wireless energy reception unit wirelessly receives the wireless energy using the magnetic resonance method while concentrating the wireless energy at a single point.

Abstract: Disclosed herein is an apparatus for transmitting and receiving wireless energy using meta-material structures having a zero refractive index. The apparatus includes a wireless energy transmission unit and a wireless energy reception unit. When external power is applied thereto, the wireless energy transmission unit generates wireless energy to be wirelessly transmitted, and then wirelessly transmits wireless energy, which is normally propagated radially when the generated wireless energy is transmitted, using a magnetic resonance method while concentrating the wireless energy in one direction.

Abstract: Disclosed herein is a dielectric resonator antenna embedded in a multilayer substrate for enhancing bandwidth. The dielectric resonator antenna includes a multilayer substrate, a first conductive plate, a second conductive plate, a plurality of first metal via holes, a feeding part configured to feed a dielectric resonator, and a conductive pattern part inserted into the dielectric resonator so that a vertical metal interface is formed in the dielectric resonator. Accordingly, the dielectric resonator antenna has low sensitivity to fabrication errors and an external environment, and can enhance the radiation characteristics of the antenna when multiple resonances occur.

Abstract: Disclosed herein is a dielectric resonator antenna using a matching substrate in order to improve a bandwidth. The dielectric resonator antenna includes: a dielectric resonator body part that is embedded in a multi-layer substrate and has an opening part on the upper portion thereof; and at least one matching substrate that is stacked on the opening part and includes an an insulating layer having a dielectric constant smaller than that of the multi-layer substrate but larger than that of air, thereby making it possible to improve the bandwidth without adjusting the size of the dielectric resonator body part and to prevent loss and change in the radiation pattern due to the substrate mode.

Abstract: Disclosed herein is a wireless energy transmission structure, which includes a printed circuit board, a disk section, and a wire section. The printed circuit board is formed in a ring type, the disk section is constituted by a first conductive plate and a second conductive plate formed on portions of the printed circuit board corresponding to each other to be spaced by a predetermined gap and a dielectric material inserted between the first conductive plate and the second conductive plate, and the wire section is constituted by a plurality of meta cells having a meta material structure, which are repetitively formed to surround the exterior and interior of the printed circuit board and a transmission line connected to each of the first conductive plate and the second conductive plate and surround the plurality of meta cells.

Abstract: Disclosed is a wireless energy transmission structure which includes a disc part including a first conductor plate and a second conductor plate which are spaced to face each other and a dielectric material inserted between the first conductor plate and the second conductor plate, and generating an electric field between the first conductor plate and the second conductor plate; and a ring-shaped wire part one end of which is connected to the first conductor plate and the other end of which is connected to the second conductor plate, and having a meta structure in which a plurality of meta cells is repetitively arranged so as to induce a magnetic field using the electric field, so that the wireless energy transmission structure is reduced in size and is improved in transmission distance and transmission efficiency.

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: Disclosed is a dielectric resonator antenna embedded in a multilayer substrate, which includes a multilayer substrate, a first conductor plate having an opening, a second conductor plate formed on the bottom of a lowermost insulating layer resulting from stacking at least two insulating layers downward from the first conductor plate, a plurality of metal via holes passing through around the opening at a predetermined interval, and a feeder for transmitting a frequency signal to the dielectric resonator embedded by the metal boundaries defined by the first conductor plate, the second conductor plate and the plurality of metal via holes, thus exhibiting low sensitivity to fabrication error and the external environment.

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 successive approximation analog/digital converter includes a sample & hold part sampling and holding an intensity of an analog input signal using a single clock cycle of a clock signal; a first comparator comparing the intensity of the analog input signal with comparison voltages determined according to estimated digital values per clock cycle following an operating clock cycle of the sample & hold part; a second comparator comparing the intensity of the analog input signal with a value equal to ½ of a preset reference voltage in the latter half of the operating clock cycle of the sample & hold part; a successive approximation register determining a value of an MSB of a digital value to be converted according to the comparison result of the second comparator and values of bits successive to the MSB according to the comparison result of the first comparator, and generating the estimated digital values by applying estimated values to undetermined bits; and a digital/analog converter generating the

Abstract: A broadband active circuit with a feedback structure includes: an active load unit providing a load varied according to a control voltage; an active circuit unit connected between the active load unit and a ground and outputting a signal corresponding to a pre-set bandwidth, among input signals; and a feedback circuit unit formed between an output terminal of the active circuit unit and the active load unit and providing a signal from the output terminal of the active circuit unit to the active load unit.

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.