TY - GEN AU - 김동우 DA - 2015/05 PY - 2015 SN - 9783800739769 UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-84979697123&origin=inward&txGid=05d9cf438cb56f2943787e4dd0091d1f UR - http://hdl.handle.net/20.500.11754/34004 AB - In this paper, we study a cognitive radio (CR) communication system in which multiple antennas assist the secondary user to achieve transmission diversity, while the constraint of zero interference to the primary user is satisfied. In particular, by assuming perfect channel state information between a secondary transmitter (ST) and a primary receiver (PR) at ST, a closed form expression for a opportunistic nulling scheme, which guarantees to meet zero interference between ST and PR, is obtained. Further, ns antennas of ST and np antennas of PR provide ns-np diversity order for one primary user. In addition, all primary users use the orthogonal spectrum. Finally, if there are M primary users, we can achieve ∑m=1 M(ns-np m ) diversity order. Numerical results regarding the effects of the number of the primary users, ST's antennas and PR's antennas are provided to evaluate the performances of the proposed scheme. © VDE Verlag GMBH, Berlin, Offenbach, Germany. PB - Institute of Electrical and Electronics Engineers Inc. KW - Null-space projection KW - Opportunistic nulling KW - Singular value decomposition KW - Channel state information KW - Cognitive radio KW - Communication channels (information theory) KW - Radio transmission KW - Singular value decomposition KW - Closed-form expression KW - Diversity analysis KW - Null space KW - Nulling KW - Numerical results KW - Perfect channel state information KW - Secondary spectrums KW - Transmission diversity KW - Antennas TI - Closed-form Outage and Diversity Analysis of Opportunistic Nulling for Secondary Spectrum Sharing ER -