Abstract:
인지 무선 시스템에서의 스펙트럼 센싱 방법, 전송휴지기간 배치 방법, 이를 위한 단말, 기지국 및 슈퍼프레임 구조가 개시된다. 이 방법은 기지국과의 통신을 수행하는 통신 단계; 및 상기 인지 무선 시스템에서 사용되는 주파수채널들의 전송휴지 기간마다, 상기 전송휴지기간을 갖는 주파수채널에 대한 스펙트럼 센싱을 수행하는 센싱 단계를 포함하고, 상기 각 주파수채널들의 전송휴지기간은 서로 중첩되지 않음을 특징으로 한다. 본 발명에 따르면, 인지 무선 시스템에서 원래 사용자(Incumbent User)의 출현여부 검출의 신뢰도를 높일 수 있다.
Abstract:
다중 안테나 OFDM 송신기는 주파수 영역에서의 데이터 심볼들을 복수 개의 부그룹들로 나누는 부그룹 생성부; 상기 복수 개의 부그룹들 각각에 대응하는 시간 영역에서의 부분 신호들을 생성하기 위하여 상기 복수 개의 부그룹들에 대해 개별적으로 고속 푸리에 역변환을 수행하는 IFFT 수행부; 상기 부분 신호들 각각이 복수 개의 송신 안테나들 중 어느 하나로 전송될 수 있도록 상기 부분 신호들의 조합을 이용하여 적어도 둘의 OFDM 신호 후보들을 생성하는 OFDM 신호 후보 생성부; 및 상기 적어도 둘의 OFDM 신호 후보들 중 어느 하나를 선택하는 선택부를 포함한다.
Abstract:
PURPOSE: A communication device including a spectrum sensing antenna and a data transceiving antenna in a cognitive radio communication system and an antenna switching method in the communication device are provided to select an optimal antenna from antennas according to the quality of a currently performing channel. CONSTITUTION: A quality measuring unit(851) measures information related to the quality of a channel different from a channel between a communication device and another communication device based on data received from the communication device through a primary antenna or a secondary antenna. A determining unit(852) determines whether the channel has a better state than another channel based on the measured information. If the state of the channel is not better than another channel based on the determined result, a control unit(853) controls a switch to mutually change connection targets of the primary antenna and the secondary antenna. [Reference numerals] (810) Primary antenna; (820) Secondary antenna; (830) Data transceiver; (840) Spectrum generator; (850) Switching processor; (851) Quality measuring unit; (852) Determining unit; (853) Control unit;
Abstract:
A method and apparatus for adaptively transmitting the same data, i.e., multicast/broadcast data, according to channel quality to a receiving group including one or more terminals that request the same service in a wireless network. A base station obtains feedback on channel quality indications (CQIs) from a plurality of terminals, selects a transmission technique that satisfies desired service quality based on the COIs, and transmits data to the terminals included in a receiving group by using the selected transmission technique. The CQIs to be transmitted from the terminals in the receiving group to the base station are transmitted through a previously allocated common CQI feedback channel. In the present invention, in order to reduce a CQI feedback channel capacity, the base station does not allocate a common CQI feedback channel with respect to each reception terminal and allocates radio resources according to CQI levels. As radio resources are allocated according to CQI levels, a CQI feedback channel capacity may not be increased even when the number of terminals in the receiving group is increased and adaptive transmission may be efficiently performed.
Abstract:
PURPOSE: A method for transmitting and receiving data for the OFDM(Orthogonal Frequency Division Multiplexing) of multiple antenna and an apparatus thereof are provided to reduce the number and the complexity of IFFT(Inverse Fast Fourier Transform), when IFFT wholly is operated, by performing IFFT at each subgroup. CONSTITUTION: A subgroup generating unit(230) divides data symbols into a plurality of subgroups at a frequency domain. An IFFT performing unit(240) individually proceeds IFFT in a plurality of the subgroups to generate partial signals at a time domain which corresponds to a plurality of the subgroups. An OFDM(Orthogonal Frequency Division Multiplexing) signal candidate generation unit(250) generates at least two OFDM signal candidates using the combination of partial signals to transmit each partial signal to one of a plurality of transmission antennas. A selecting unit(260) selects at least one of two OFDM signal candidates.
Abstract:
PURPOSE: A method and a device for controlling transmission power of a cognitive radio device are provided to guarantee reliable communication of the cognitive radio device, thereby minimizing interference for a licensed user. CONSTITUTION: A CR(Cognitive Radio) device obtains CR environment information for a licensed user or an unlicensed user which occupies an adjacent cell or an adjacent channel of the CR device(802). The CR device determines a transmission power value by the CR environment information(804). The CR device generates transmission power control information including the transmission power value(806). The CR device controls transmission power by the transmission power control information(808).