Electronics and Telecommunications Research Institute

Sung-Jin You

Myung-Sun Song

Gwangzeen Ko

Chang-Joo Kim

Jung-Sun Um

Moon-Won Lee

Sung-Hyun Hwang

Min-Soo Kang

Tae-Jin Chung

Young-Jun Chong

Provided is a hybrid beaconing method in which a centralized beaconing scheme and a distributed beaconing scheme are combined. In the hybrid beaconing method, a beaconing scheme is converted according to a network condition, and a centralized beaconing scheme or a distributed beaconing scheme is used to maintain an optimum network status.

Hybrid beaconing method

Provided is a method and apparatus for efficiently transmitting and receiving a frame including a header and a payload in a communication system. If the number of repeated items in the content of a header of the frame is high, specific preambles are allocated to the repeated items and the repeated items are omitted. Accordingly, data transfer efficiency can be improved.

Method and apparatus for compressing frame

A resource reservation method between a master device and a slave device or between slave devices in a centralized network. In resource reservation between slave devices, optimal resources may be allocated by performing link measurement between the slave devices before allocating the resources.

Reserving resources in centralized network by scanning superframes equal to or greater than maximum number of superframes allowed without listening to beacon period

A channel switching method is provided for a base station to allocate a slot for data exchange with each of a plurality of terminals in a frequency channel that is not used by an incumbent user (IU). The method includes include transmitting a channel switching message for requesting to switch to a backup channel when a signal of the IU is sensed in the frequency channel; transmitting a beacon frame via the backup channel, wherein the beacon frame comprises allocation information about slots which are in the frequency channel and which are respectively allocated to each of the plurality of terminals; and allocating the slot for data exchange with each of the plurality of terminals to the backup channel according to the allocation information, and communicating with each of the plurality of terminals.

Channel switching apparatus and method of a base station and channel switching apparatus and method of a terminal based on the cognitive radio system

A non-coherent synchronous direct-conversion receiving apparatus is provided. The apparatus includes a RF receiving unit, an I/Q ADC unit, and a digital signal processing unit for analyzing the digital signal received from the I/Q ADC unit to adjust a bandwidth of a variable receiving filtering unit according to the analyzing result, compensating a frequency offset to be correspondent with a symbol transmitting rate by extracting frequency offset information from the digital signal, compensating a frequency offset using the analyzing result, and applying a voltage corresponding to a sum of compensating values to the RF receiving unit. Therefore, the apparatus can compensate a frequency offset regardless of the magnitude of a frequency offset and performs a stable AFC operation through varying the bandwidth of a receiving filter by estimating the frequency offset with only data information, and adjusting a reference frequency twice through an interface signal.

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Daejeon, South Korea

Sung-Jin You