• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.10a
• /
• pp.609-610
• /
• 2017

Cognitive radio communication techniques have been attracting attention to efficiently use the scarce spectrum as the wireless communication service increases. In cognitive radio communication, efforts to minimize interference to the primary user are important technical factors. In a multi-hop wireless ad hoc network, multi-hop transmission requires path and channel selection considering channel interference as well as collision with primary users. In the multi-channel environment, cognitive radio network has different capacities depending on the inter-channel interference and collision with the main users. In this paper, we propose a multi-hop transmission scheme that minimizes inter-channel interference and reduce collision with primary users.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.6
• /
• pp.1148-1156
• /
• 2015

The maritime cognitive radio networks (MCRNs) provide the high throughput with a low communication cost because the secondary ships opportunistically access to unused licensed bands of primary ships. In the ground cognitive radio networks, the busy and idle state of a primary user during a frame is not nearly changed because the state of the primary user are slowly changed. However, the state of the primary ship in the MCRNs may be frequently changed in the frame. Therefore, this paper evaluates the throughput of a primary ship and secondary ships in the MCRNs taking the state change of a primary ship into consideration when the fusion center uses the cooperative spectrum sensing. The simulation results show that trade-off between the throughput of a primary ship and that of secondary ships according to the system parameter such as the cooperative spectrum sensing scheme, the number of secondary ships, and the target detection probability.

• Journal of Internet Computing and Services
• /
• v.12 no.2
• /
• pp.75-83
• /
• 2011

Wireless services and devices that use frequency increase more and more because of advancement of the industry. Therefore, the available spectrum band becomes increasingly insufficient. Cognitive Radio, which adaptively utilizes the vacant licensed spectrum band, is considered as an effective way to utilize the spectrum resource shortage. CR user should move from current allocated channel to vacant channel to avoid the interference to the primary user when the primary user appears in the current channel. In this case, CR system undergoes the break off time until handshake is completed. So, in order to guarantee the Quality of Service(QoS) of CR system, fast handshake method is required. In this paper, we propose the embedded control signal transmission technique to reduce the break off time. This method can transmit the control signals in data transmission period as well as the broadcasting period. Proposed method can improve the data throughput and decrease the break off time. Computer based simulation proves that our proposed scheme outperforms conventional one.

• Journal of the Institute of Convergence Signal Processing
• /
• v.13 no.3
• /
• pp.156-161
• /
• 2012

Random access protocol takes advantage of constructing a decentralized wireless network due to its intrinsic spectrum sensing capability. Such technical feature goes well with cognitive radio networks consisting of heterogeneous wireless systems, in which a centralized control between heterogeneous wireless systems is hard to be implemented. Motivated by the decentralized feature of the random access, we adopt the random access protocol in cognitive radio networks, and evaluate the performance of a CSMA-based cognitive radio network.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.5
• /
• pp.1043-1050
• /
• 2018

In this paper, we propose a reinforce learning based on cooperative sensing scheme to select optimal secondary users(SUs) to enhance the detection performance of spectrum sensing in Cognitive radio(CR) networks. The SU with high accuracy is identified based on the similarity between the global sensing result obtained through cooperative sensing and the local sensing result of the SU. A fusion center(FC) uses similarity of SUs as reward value for Q-learning to determine SUs which participate in cooperative sensing with accurate sensing results. The experimental results show that the proposed method improves the detection performance compared to conventional cooperative sensing schemes.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.5
• /
• pp.73-82
• /
• 2013

최근 차량 네트워크(VANET)는 차량 및 도로 안전에 관한 정보와 다양한 인포테인먼트 서비스 증가로, 기존 차량 통신에 고정적으로 할당된 주파수로는 요구되어지는 주파수 수요량을 충족하지 못할 것으로 예측된다. 이에 따라, 인지 무선(CR) 기술을 VANET 환경의 특징에 적합하게 적용함으로써, 동적인 주파수 사용으로 주파수의 활용도를 향상시키기 위한 연구가 큰 관심을 받고 있다. 본 고에서는 인지 무선을 이용한 차간 통신 이슈 및 연구 동향을 소개한다.

• Information and Communications Magazine
• /
• v.27 no.8
• /
• pp.37-42
• /
• 2010

최근 학계에서 많이 연구되고 있는 무선인지기술(CR : Cognitive Radio)을 실제 하드웨어로 구현하는 경향이 두드러지고 있다[1,2]. 또한 IEEE 802.22의 표준화가 완료되고 미국의 DTV전환과 함께 무선인지기술이 본격적으로 적용되면서 연구된 결과를 실제 시스템에서 구현하여 입증할 필요성이 증가하고 있다. 본 고에서는 대표적인 오픈소스 하드웨어 플랫폼인 GNU Radio에 대해 설명하고 무선인지기술을 적용한 시스템을 소개한다.

• Information and Communications Magazine
• /
• v.32 no.11
• /
• pp.33-40
• /
• 2015

본고에서는 ITU-R M.2330 보고서를 바탕으로 유휴 무선 자원을 다른 시스템과 공유하는 인지 무선 시스템, 즉 CRS(Cognitive Radio System)를 지상 이동업무에 적용할 어플리케이션들에 대해 소개한다. 또한 CRS를 실현하기 위한 무선제어채널, 스펙트럼 센싱, 데이터베이스과 같은 정보획득 기술과 판정, 학습 기술들에 대한 세부사항에 대해 설명한다. 이후 운용 및 기술적 요구사항과 무선 자원의 공유와 공존을 위한 기술적 특징에 대해 설명하고 CRS 시스템을 적용함으로써 얻을 수 있는 스펙트럼 공유 및 시스템 네트워크 측면에서의 이득에 대해 기술한다.

• Journal of Convergence for Information Technology
• /
• v.11 no.12
• /
• pp.106-114
• /
• 2021

The needs in terms of wireless communications are growing up both for civil and military applications. Therefore a constant improvement of this technology is required to meet customer wishes. One of its main shortcomings is the inefficient use of the spectrum in which a large part of the allocated bands of frequencies is unused. Since communication is crucial, spectrum shortage problems can lead a multi-national and coalition operation to failure. Cognitive Radio Networks (CRNs) are a promising technology which continuously analyses the spectrum searching for available frequencies. It can solve this spectrum issue by avoiding interferences, improving system-wide spectral efficiency, robustness to dynamic conditions and allowing more spectrum flexibility This paper specifically analyzed and presented the application of the CRNs in the military operational environment, and presented the appropriate method applicable to each actual operational situation.

• Electronics and Telecommunications Trends
• /
• v.30 no.2
• /
• pp.104-114
• /
• 2015

최근 무선통신서비스의 수요 급증에 따른 주파수 부족 심화 현상에 대해 제한된 주파수 자원의 재분배와 같은 해결책으로는 근본적인 극복이 어렵다는 공감대를 바탕으로 주파수 공유에 대한 연구가 다양한 분야에서 진행 중이다. 특히 인지무선기술은 무선통신에 관련된 모든 기술분야와 밀접하게 연관되어 다양한 기술분야의 협업을 통한 현 문제점을 해결할 수 있는 도전 기술임은 자명하다. 인지무선기술을 적용한 다양한 기술 표준들은 마무리 되었거나 마무리 단계에 있지만, 광의적 개념의 CR(Cognitive Radio)기술 측면에서 보면 아직도 해결해야 할 기술 이슈들이 산재해 있으며, 이러한 이유로 2014년 가트너 하이프 사이클상 태동기(innovation trigger)에 위치해 있다. 따라서, 본고에서는 최근 진행되고 있는 CR 관련 국내외 표준화 동향 및 기술개발에 대해 정리하고, 해결해야 할 주요 기술별 도전 이슈들에 대해 제시하고자 한다.