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Sensing Optimization for an Receiver Structure in Cognitive Radio Systems
Kang, Bub-Joo,Nam, Yoon-Seok The Korea Institute of Information and Commucation 2011 Journal of information and communication convergen Vol.9 No.1
This paper describes the optimization of spectrum sensing in terms of the throughput of a cognitive radio (CR) system. Dealing with the optimization problem of spectrum sensing, this paper evaluates the throughput of a CR system by considering such situations as the penalty time of a channel search and incumbent user (IU) detection delay caused by a missed detection of an incumbent signal. Also, this paper suggests a serial channel search scheme as the search method for a vacant channel, and derives its mean channel search time by considering the penalty time due to the false alarm of a vacant channel search. The numerical results suggest the optimum sensing time of the channel search process using the derived mean channel search time of a serial channel search in the case of a sensing hardware structure with single radio frequency (RF) path. It also demonstrates that the average throughput is improved by two separate RF paths in spite of the hardware complexity of an RF receiver.
Performance Evaluation of Access Channel Slot Acquisition in Cellular DS/CDMA Reverse Link
Kang, Bub-Joo,Han, Young-Nam Electronics and Telecommunications Research Instit 1998 ETRI Journal Vol.20 No.1
In this paper, we consider the acquisition performance of an IS-95 reverse link access channel slot as a function of system design parameters such as postdetection integration length and the number of access channel message block repetitons. The uncertainty region of the reverse link spreading codes compared to that of forward link is very small, since the uncertainty region of the reverse link is determined by a cell radius. Thus, the parallel acquisiton technique in the reverse link is more efficient than a serial acquisition technique in terms of implementation and of acquisition time. The parallel acquisition is achieved by a bank of N parallel I/Q noncoherent correlator are analyzed for band-limited noise and the Rayleigh fast fading channel. The detection probability is derived for multiple correct code-phase offsets and multipath fading. The probability of no message error is derived when rake combining, access channel message block combining, and Viterbi decoding are applied. Numerical results provide the acquisition performance for system design parameters such as postdetection integration length and number of access channel message block repetitions in case of a random access on a mobile station.
Design Issues of Spectrum Sensing in Cognitive Radio Networks
Kang, Bub-Joo The Korea Institute of Information and Commucation 2011 Journal of information and communication convergen Vol.9 No.2
This paper investigates the design issues of spectrum sensing in the cognitive radio (CR) networks of opportunistic unlicensed spectrum access. The cognitive radios can perform a communication using the incumbent user spectrum band without the interference caused by the cognitive radio users. In this case, the cognitive radios must know the real-time radio environments of the incumbent user spectrum band using the spectrum sensing, beacon signal, and geo-location database access. Then in this paper, we are going to provide spectrum sensing issues which include the sensing techniques, the regulatory requirements, the analysis of DTV detection threshold, and main considerations associated with the spectrum sensing design in cognitive radio systems. Also, this paper introduces design trade-offs in order to optimize the sensing parameters such as sensing time and sensing complexity.
Hybrid Spectrum Sensing of Backup Channel Search Using Multiple Spectrum Sensors
Bub-Joo Kang(강법주) 제어로봇시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.3
This study introduces hybrid spectrum sensing using multiple spectrum sensors for backup channel search. Hybrid spectrum sensing combines parallel and serial spectrum sensing. In hybrid spectrum sensing, parallel spectrum sensing of the first step is performed for all the frequency channels of one channel group. These multiple frequency channels are simultaneously sensed by parallel spectrum sensors. All channel groups are then sensed by serial spectrum sensing of the second step. A system model for performance evaluation is also suggested based on the mean channel search time to search the backup channel. The numerical results suggest the optimal channel sensing time using the mean channel search time of hybrid spectrum sensing in the case of a cognitive radio device hardware structure with multiple spectrum sensors.
강법주(Bub-Joo Kang),김양수(Yang-Soo Kim),박희수(Hee-Soo Park),반상우(Sang-Woo Ban) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6
본 논문에서는 채널탐색 및 채널전환 등을 고려하여 CR(cognitive radio) 시스템의 throughput 측면에서 스펙트럼 센싱의 최적화를 다루고 있다. 또한 본 논문에서는 데이터 수신 경로와 분리된 센싱수신기를 갖는 형태의 센싱구조를 제시하고, 데이터 수신 경로를 센싱 수신기로 사용하는 경우와 분리된 센싱 수신기를 갖는 센싱 구조와의 센싱 성능을 CR 사용자의 throughput 관점에서 비교하고 있다. 수치해석의 결과로는 incumbent 신호가 출현한 경우 채널이동을 위한 다른 빈 채널의 탐색에서 데이터 통신 경로와 분리된 센싱수신기에 의한 채널탐색을 통하여 throughput 효율이 향상됨을 보여주고 있다. 또한 수치해석결과에서는 incumbent 신호검출 성능에 의해 야기되는 IU 검출 지연 시간에 따른 채널감시시간 대비 throughput 효율을 보여주고 있다.