Electronics and Telecommunications Research Institute

University-industry Cooperation Group of Kyung Hee University

Sung-Hyun Hwang

Chang-Joo Kim

Myung-Sun Song

Jung-Sun Um

Gwangzeen Ko

Byung-Jang Jeong

Yun Hee Kim

Sung-Jin You

Jin Soo Wang

Bub-Joo Kang

Sung-Jin Yoo

Sang-Won Kim

Myung Sun Song

Jung Sun Um

Chung-Gu Kang

Jae Cheol Park

Jae-Ick Choi

Yun-Hee Kim

Changhyun Park

Min-Sheo Choi

Moon-Won Lee

Hyung-Rae Park

Il-Hwan Kim

Gwang-Zeen Ko

Jae Chul Park

Jung-Sun 408-205 Jugong-4Danji Apt 908 Um

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.

Method of generating pilot pattern for adaptive channel estimation in OFDMA systems, method of transmitting/receiving using the pilot pattern and apparatus thereof

Disclosed herein are a method and a system for performing initial ranging in a cognitive radio network The method for performing initial ranging in a cognitive radio network includes: detecting signals received in one or more ranging sections; estimating a tint time offset based on a correlation between subcarrier indices of the signals detected in the one or more ranging sections; estimating a second time offset based on correlations for the signals detected in the one or more ranging sections and a plurality of codes that are predetermined and detecting an initial ranging code among the plurality of codes; and estimating a time offset of a CPE performing initial ranging with the detected initial ranging code using the first time offset and the second time offset that are estimated.

Method and system for performing initial ranging in cognitive radio network

A method and an apparatus for controlling transmit power of a CR device are provided. The method includes acquiring CR environment information regarding a licensed user or an unlicensed user occupying an adjacent channel or an adjacent cell of the CR device; determining a transmit power value of the CR device using the CR environment information; and generating transmit power control information including the transmit power value. The method and apparatus guarantee reliable communication of the CR device and minimize interference with the licensed user.

Transmission power control method and device for cognitive radio device

Disclosed herein are an apparatus and a method of estimating a channel in consideration of a residual synchronization offset. The apparatus of estimating a channel in consideration of a residual synchronization offset includes: a channel estimating unit estimating the channel using pilots scattered over a plurality of OFDM symbols and calculating a first channel estimated value as the estimation result, in the case in which an OFDM symbol estimating the channel and an OFDM symbol compensating for the channel are different from each other; and a phase reflecting unit calculating a phase generated by the residual synchronization offset in proportion to a difference between a channel estimation time and a channel compensation time, reflecting the calculated phase in the first channel estimated value, and calculating a second channel estimated value as the reflection result.

Apparatus and method of estimating channel in consideration of residual synchronization offset

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 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.

Method and device for communication between devices with different transmission coverage

Provided are a method of adaptively allocating appropriate hybrid bursts according to terminal attributes including terminal position, channel state, and service type in an orthogonal frequency-division multiple access (OFDMA) system, and an upstream-MAP information element (US-MAP IE) structure supporting the method. The method includes dividing an upstream subframe into a plurality of zones depending on the number of OFDMA symbols and allocating bursts of a zone to a terminal according to the terminal attributes. Bursts are formed by allocating slots along a time axis in the upstream subframe, and are formed by allocating slots along a frequency axis in a downstream subframe.

Method and apparatus of hybrid burst mapping in OFDMA systems

Provided is a transmitter for transmitting an orthogonal frequency division multiplexing (OFDM) signal using multiple antennas, including: a subgroup generator to divide data symbols of a frequency domain into a plurality of subgroups; an inverse fast Fourier transform (IFFT) unit to perform an IFFT with respect to each of the subgroups so as to generate partial signals of a time domain corresponding to the plurality of subgroups, respectively; a candidate OFDM signal generator to generate at least two candidate OFDM signals using a combination of the partial signals so that each of the partial signals is transmitted to one of transmit antennas; and a selector to select one of the at least two candidate OFDM signals.

Method of transmitting and receiving orthogonal frequency division multiplexing (OFDM) signal using multiple antennas, and transmitter and receiver thereof

Provided are methods of spectrum sensing and assigning quiet periods in a cognitive radio system in order to increase the reliability of detection regarding whether an incumbent user appears in his/her frequency channel, customer premises equipment (CPE), a base station, and the structure of a super frame for performing the methods. The spectrum sensing method includes communicating with a base station (BS) and performing spectrum sensing for frequency channels having quiet periods (QPs) during the QPs of the frequency channels used in the cognitive radio system, wherein the QPs of the frequency channels do not overlap each other

Method for sensing spectrum and arranging quiet period in cognitive radio system, customer premise equipment, base station and superframe structure using the same

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 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 CQIs, 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.

Method and apparatus for link adaptive multicast/broadcast transmission and reception

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.

Network communication method and network device using preamble

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.

Growing community of inventors

Daejeon, South Korea

Sung-Hyun Hwang