公开(公告)号：CA2708838C

公开(公告)日：2016-02-02

申请号：CA2708838

申请日：2008-12-05

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： KO GWANGZEEN ,  YOU SUNG-JIN ,  SONG MYUNG-SUN ,  HWANG SUNG-HYUN ,  UM JUNG-SUN ,  KIM CHANG-JOO

IPC: H04B7/155

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. A channel switching apparatus and method thereof of a base station, which allocates a slot for data exchange with each of a plurality of terminals in a frequency channel that is not used by the IU and thus performs communication, 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. By doing so, frequency resources between each of networks can be efficiently used, and convenience and efficiency with respect to network operation can be maximized.

公开(公告)号：CA2625370C

公开(公告)日：2014-09-16

申请号：CA2625370

申请日：2006-10-13

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： KANG BUB-JOO ,  SONG MYUNG-SUN ,  KIM CHANG-JOO

IPC: H04W72/00 ,  H04J1/00 ,  H04W16/14 ,  H04W72/04 ,  H04W72/08

Abstract: Provided is a method of assigning a frequency channel using efficient spectrum sensing in a multiple Frequency Assignment (FA) system. The method includes a channel sensing process, wherein a base station (BS) of a secondary user classifies multiple frequency channels licensed to a primary user into a plurality of channel state sets according to usage states, periodically senses channel states by changing a sensing period according to the types of classified channel state sets, and manages the sensed channel states as frequency channel state set information; a channel state set broadcasting process, wherein the BS transmits the frequency channel state set information managed in the channel sensing process to secondary user terminals using a broadcast message; and a channel assigning process, wherein if the BS receives a channel assignment request message from a new secondary user terminal which has received the broadcast message, the BS assigns an unused frequency channel from among frequency channels licensed to the primary user to the new secondary user terminal using the frequency channel state set information. Accordingly, a frequency channel can be assigned to a secondary user requesting channel assignment using frequency channel state set information without a primary user experiencing interference noise.

公开(公告)号：GB2479486A

公开(公告)日：2011-10-12

申请号：GB201112226

申请日：2009-12-15

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： KO GWANGZEEN ,  LEE MOON-WON ,  YOU SUNG-JIN ,  HWANG SUNG-HYUN ,  UM JUNG-SUN ,  SONG MYUNG-SUN ,  KIM CHANG-JOO

IPC: H04W48/08

Abstract: 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.

公开(公告)号：CA2650462C

公开(公告)日：2013-01-22

申请号：CA2650462

申请日：2007-04-24

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： HWANG SUNG-HYUN ,  KIM CHANG-JOO ,  SONG MYUNG-SUN ,  UM JUNG-SUN

IPC: H04L27/26

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.

公开(公告)号：GB2464885B

公开(公告)日：2012-02-29

申请号：GB201003269

申请日：2008-09-04

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： PARK CHANGHYUN ,  SONG MYUNG-SUN ,  KIM SANG-WON ,  LIM SUNMIN

IPC: H04W72/04 ,  H04W16/14

Abstract: A method for managing a channel set for dynamic channel allocation, and a system for performing the method. The method includes predicting a channel state and a channel quality on a vacant channel based on channel information that is obtained by spectrum sensing and communication protocol. The predicting includes modeling an occupation pattern of the vacant channel to calculate a probability in which an incumbent user (IU) licensed to use the vacant channel appears on the vacant channel. The method also includes evaluating reliability on the prediction result, and giving a priority to the vacant channel based on the evaluated reliability.

公开(公告)号：CA2689496A1

公开(公告)日：2008-12-24

申请号：CA2689496

申请日：2008-06-11

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： KO GWANGZEEN ,  KIM CHANG-JOO ,  SONG MYUNG-SUN ,  HWANG SUNG-HYUN ,  UM JUNG-SUN

IPC: H04L27/26

Abstract: 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 supp orting the method. The method includes dividing an upstream subframe into a plurality of zones depending on the number of OFDMA symbols and allocating b ursts of a zone to a terminal according to the terminal attributes. Bursts a re formed by allocating slots along a time axis in the upstream subframe, an d are formed by allocating slots along a frequency axis in a downstream subf rame.

公开(公告)号：CA2629880C

公开(公告)日：2015-09-29

申请号：CA2629880

申请日：2006-11-16

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： KO GWANGZEEN ,  HWANG SUNG-HYUN ,  KANG BUB-JOO ,  KANG CHUNG-GU ,  KIM IL-HWAN ,  KIM CHANG-JOO ,  SONG MYUNG-SUN

IPC: H04B7/26

Abstract: Provided are a channel switching method for effectively performing channel switching in a cognitive radio system while protecting an incumbent user, a method of managing a frequency channel, and a base station and customer premises equipment (CPE) using the methods. In the channel switching method performed by the base station, a currently unavailable first frequency channel is detected from among at least one uplink/downlink frequency channel which is set as a communication channel with the CPE; a channel switching request message requesting switching from the first frequency channel to a second frequency channel is transmitted to the CPE; and the first frequency channel is switched to the second frequency channel when a channel switching report message reporting that channel switching is to be performed in response to the channel switching request message is received from the CPE.

公开(公告)号：CA2760269A1

公开(公告)日：2010-11-04

申请号：CA2760269

申请日：2010-04-29

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： HWANG SUNG-HYUN ,  KO GWANGZEEN ,  KIM CHANG-JOO ,  SONG MYUNG-SUN ,  UM JUNG-SUN ,  CHOI MIN-SHEO

IPC: H04W52/00 ,  H04W52/04 ,  H04W52/34

Abstract: The present invention relates to a transmission power control method and device. The transmission power control method for a cognitive radio device according to one embodiment of the present invention includes obtaining CR environmental information about a registered user or an unregistered user occupying an adjacent channel or an adjacent cell of a cognitive radio device, determining a transmission power value of the cognitive radio device using the CR environmental information, and generating transmission power control information including a transmission power value. According to the present invention, the reliable communication of the cognitive radio device can be guaranteed and at the same time interference for a registered user can be minimized.

公开(公告)号：CA2684306A1

公开(公告)日：2008-10-30

申请号：CA2684306

申请日：2008-04-21

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： SONG MYUNG-SUN ,  KIM CHANG-JOO ,  HWANG SUNG-HYUN ,  UM JUNG-SUN

IPC: H04L27/26

Abstract: Provided is a method and apparatus of generating signals for initial rang ing in an Orthogonal Frequency Division Multiple Access (OFDMA) system. The method, includes: generating a plurality of ranging symbols by cyclic-shifti ng sample data of a ranging symbol in one OFDMA symbol period as much as a v alue obtained by multiplying a cyclic prefix size by a symbol index; generat ing a ranging signal by copying a rear part corresponding to the cyclic pref ix size in the sample data with respect to each of the ranging symbols and i nserting the copied rear part in front of the sample data as a cyclic prefix .

公开(公告)号：CA2650462A1

公开(公告)日：2007-11-01

申请号：CA2650462

申请日：2007-04-24

Applicant: KOREA ELECTRONICS TELECOMM

Inventor： SONG MYUNG-SUN ,  UM JUNG-SUN ,  HWANG SUNG-HYUN ,  KIM CHANG-JOO

IPC: H04L27/26

Abstract: Provided is a method of trasmitting/receiving an OFDM signal in which pilots are inserted, the pilots having a repeated 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.