Abstract: A data transmitter and receiver for improving a data rate, and more particularly, to an apparatus and method of transmitting and receiving an orthogonal frequency division multiplexing (OFDM) symbol in which a pilot signal is added to a data signal is provided.

Abstract: Provided is a small monopole antenna having a loop feeder. The small monopole antenna having a loop feeder includes: a loop element forming a loop along a predetermined plane and having a loop feeder at the center thereof; a non-feeding type monopole antenna element including one end connected to a wire of the loop element and other end connected to a ground unit by being bended at the center of the loop element; a ground unit for grounding other end of the non-feeding type monopole antenna; and a first connecting unit for connecting the non-feeding type monopole antenna to an external device for feeding the loop feeder of the loop element through the non-feeding type monopole antenna.

Abstract: An antenna with controlled sidelobe characteristics includes: a power coupler configured to receive a signal to be transmitted and generate and output a main channel signal and an auxiliary channel signal; a main channel power distributor configured to receive the outputted main channel signal and distribute power of the main channel signal; a main antenna configured to receive the power-distributed signal, the main antenna including a one-dimensional or two-dimensional array of a number of antenna elements; a vector signal controller configured to control amplitude and phase of the auxiliary channel signal; an auxiliary channel power distributor configured to receive the controlled amplitude and phase of the auxiliary channel signal and distribute power of the auxiliary channel signal; and an auxiliary antenna independently installed separate from the main antenna, the auxiliary antenna including an antenna element or an array of a number of antennas.

Abstract: Provided is a large range management device (LRMD) of managing a communication between a plurality of small range devices (SRDs) and a plurality of large range devices (LRDs), the SRDs and the LRDs being located in a single cell and having different transmission coverage, the LRMD including an access slot allocation unit to allocate an SRD access slot to a radio resource for a downlink, to enable a first SRD to request an association from a network, a selection unit to select a communication relay device for relaying relay data of the first SRD, a relay slot allocation unit to allocate at least one SRD relay slot to a radio resource for an uplink, to enable the communication relay device to relay the relay data to a second SRD or another LRD, and a receiving unit to receive the relay data based on the at least one SRD relay slot

Abstract: Provided are a transmitter and a receiver. The transmitter combines N data signals received from an encoded bit stream to generate N symbols; maps the N symbols to subcarriers that are spaced more than a coherent bandwidth apart; and receives and moves the N symbols, which are mapped to the subcarriers that are spaced more than a coherent bandwidth apart, to their own positions. The receiver demodulates N pieces of data using the N symbols received from the transmitter in a manner similar to that used by the transmitter.

Abstract: Provided is a method of generating a pilot pattern capable of perform adaptive channel estimation, and a method and apparatus of a base station and a method and apparatus of a terminal using the pilot pattern. The pilot pattern selects pilot symbol positions based on distances from pilots of previous orthogonal frequency division multiple access (OFDMA) symbols to a subcarrier position of a current OFDMA symbol in the frequency domain and the time domain, so that a low pilot density is maintained so as to effectively transmit data, and stable channel estimation performance can be obtained even in a bad channel environment. In addition, the minimum burst allocation size is determined according to the channel environment between the base station and the terminal, guaranteeing channel estimation performance suitable for the channel environment, and improving granularity, channel estimation latency, and channel estimation memory size.

Abstract: Provided is a method of generating a pilot pattern capable of perform adaptive channel estimation, and a method and apparatus of a base station and a method and apparatus of a terminal using the pilot pattern. The pilot pattern selects pilot symbol positions based on distances from pilots of previous orthogonal frequency division multiple access (OFDMA) symbols to a subcarrier position of a current OFDMA symbol in the frequency domain and the time domain, so that a low pilot density is maintained so as to effectively transmit data, and stable channel estimation performance can be obtained even in a bad channel environment. In addition, the minimum burst allocation size is determined according to the channel environment between the base station and the terminal, guaranteeing channel estimation performance suitable for the channel environment, and improving granularity, channel estimation latency, and channel estimation memory size.

Abstract: Provided are Circular Polarized Helical Radiation element and its Array Antenna operable in TX band and RX band. The circular polarized helical radiation element and its array antenna and the antenna with double reflection boards using that array can operate at TX/RX dual band which is high frequency such as Ka band by operating the helical antenna in axial mode and implementing dual feeding structure. The array antenna having a number of radiation elements operable in the both of TX band and RX band, wherein the radiation elements are arrayed on predetermined column lines, each radiation element comprising: a helix for radiating orthogonal circular polarized waves in the different frequency bands wherein the helix is fed at its beginning point and its terminating point; and a wave guide for accommodating the helix.

Abstract: Provided is a contention-based data communication apparatus and method that may notify that a radio resource is to be used using a search signal prior to transmitting a communication frame, and may transmit data based on a priority when a search signal received from another communication apparatus is detected.

Abstract: A rotor blade for a rotary wing aircraft, which rotates about and is combined with a rotation shaft of the rotary wing aircraft. The rotor blade includes a body combined with the rotation shaft and including a leading edge that is a front edge in a direction of rotation; and a plurality of deformable protrusions formed on the leading edge of the body in a radial direction of rotation, and deformable between a first shape protruding forward in the direction of rotation and a second shape not protruding forward in the direction of rotation such that BVI noise generated when a vortex formed near a blade tip collides with the rotor blade is selectively reduced whenever necessary. The deformable protrusions are formed in a region from a point spaced apart from the rotation shaft by 75% of a radius of rotation to a point spaced apart from the rotation shaft by 90% of the radius of rotation.

Abstract: Provided is a method of generating a pilot pattern capable of perform adaptive channel estimation, and a method and apparatus of a base station and a method and apparatus of a terminal using the pilot pattern. The pilot pattern selects pilot symbol positions based on distances from pilots of previous orthogonal frequency division multiple access (OFDMA) symbols to a subcarrier position of a current OFDMA symbol in the frequency domain and the time domain, so that a low pilot density is maintained so as to effectively transmit data, and stable channel estimation performance can be obtained even in a bad channel environment. In addition, the minimum burst allocation size is determined according to the channel environment between the base station and the terminal, guaranteeing channel estimation performance suitable for the channel environment, and improving granularity, channel estimation latency, and channel estimation memory size.

Abstract: A CR apparatus for performing communication in a CR network includes: a communication unit configured to measure a channel estimation signal, transmit measured channel state information to a master device, and, when a QP of a reference channel arrives, make a communication channel transition to a candidate channel and perform communication; and a channel information management unit configured to receive and manage the channel state information measured by the communication unit and channel information comprising a candidate channel, into which a channel transition is to be made during a QP of the reference channel, received from the master device and control channel transition of the communication unit based on the channel information.

Abstract: Provided is a antenna system for tracking a mobile satellite and a movable carrier having the same for mechanically adjusting the orientation of an antenna at the azimuth angle and the elevation angle and correcting the phase error of a receiving signal while adjusting the elevation angle of the antenna at the same time. The antenna system for tracking a mobile satellite includes: a substrate; a rotating plate rotatably disposed on the substrate; one or more antennas disposed at the rotating plate; an azimuth angle adjusting unit for mechanically adjusting an azimuth angle of the antenna; and an elevation angle adjusting unit for mechanically adjusting an elevation angle of the antenna.

Abstract: Provided is a transmitting/receiving isolation antenna that can perform wireless bi-directional communication in the co-channel, co-polarization and co-time by acquiring high isolation from transmitting and receiving antennas having co-time, co-channel and co-polarization and set up adjacently. The isolation antenna includes a first antenna; second and third antennas symmetrically positioned in the same distance from the first antenna; a shielding unit symmetrically positioned between the first and second antennas, and between the first and third antennas; and a signal removing unit for removing a signal transmitted from the first antenna to the second and third antennas.

Abstract: In a cognitive radio system, when communication in an operational channel is determined to be discontinued due to that an incumbent user (IU) entering the operational channel that is currently being used or due to that an excessive interference occurring in the operational channel, the operational channel is switched to a pre-arranged channel. However, since some parameters are different between the operational channel and the pre-arranged channel, an initialization procedure has to be performed to allow the cognitive radio system to be adapted to those some parameters. Since an initialization technique aiming for this situation is not developed yet, a conventional cognitive radio system uses a general initialization technique used to initially operate a system. However, the general initialization technique has to allow the system to be adapted to many parameters so that it takes a relatively long initialization time.

Abstract: Provided is a method for calculating a path loss using reflection paths as dominant paths. The method includes determining a reflection plane and a reflection point in case of reflection; calculating electric field strength for the determined reflection plane and reflection point; calculating electric field strength based on a statistical loss value by diffraction according to a propagation environment in case of diffraction; and calculating a path loss based on the calculated electric field strength for reflection and the calculated electric field strength for diffraction.

Abstract: Provided are a transmission power determining method and an apparatus thereof for parallel transmission of a plurality of streams. In a wireless communication system, the transmission power determining method and apparatus determine a transmission power suitable for allowing the plurality of streams to be simultaneously and reliably transmitted in a mutually permissible interference range, and use a Hidden Handshaking (HHS) procedure to determine the transmission power. By doing so, it is possible to perform reliable channel allocation and to reliably transmit the plurality of streams.

Abstract: Provided are a method of managing multiple channels in a single network, and a network management device, also referred to as a network management system. According to the method and the network management device, all devices in one network that operate by using multiple channels share core information, and are effectively controlled.

Abstract: Provided are a beacon re-broadcasting apparatus, a beacon re-broadcasting method, and an initial access request method in a wireless network. In the re-broadcasting apparatus and method, a beacon frame including beacon information for communications in the wireless network and information on an echo beacon slot allocated for beacon re-broadcasting among time slots of a superframe is received from a management device for managing the wireless network in which a plurality of terminals communicated with each other through the superframe including time-divided time slots, and the beacon information is re-broadcasted during the echo beacon slot. Accordingly, the beacon information can be received in various environments, and the beacon information can be received to an adjacent network in addition to the corresponding network. Therefore, frequency resources can be shared and effectively used between networks, and convenience and efficiency in network operation can be maximized.

Abstract: Provided are a network communication method and a network device using a preamble. According to the network communication method and the network device, network coexistence is easily achieved by using network identification transmitted in the preamble, and an unknown terminal, which has a low reception signal to noise ratio (SNR) and has not yet been connected to an existing network, is easily connected to the existing network.