TY - GEN
T1 - Beamforming in cognitive radio with partial channel state information
AU - Noh, Jung Hoon
AU - Oh, Seong Jun
PY - 2011
Y1 - 2011
N2 - This paper focuses on a downlink beamforming problem in the cognitive radio (CR) communication system where primary users (PU) coexist with secondary users (SU). It is assumed that the SU transmitter has multiple antennas and transmits data to another SU's single-antenna receiver using the beamforming technique. By properly designing a beamforming vector, SU can maximize its channel gain while maintaining an interference with PU below a predefined level. In order to construct an optimal beamforming vector, the SU transmitter requires knowledge of the downlink channel information of both PU and SU receivers sent on the feedback channel. However, it is impractical to assume that the transmitter has the perfect channel state information (CSI) considering the tremendous feedback overhead. One way to tackle this feedback overhead problem is to use a finite number of feedback bits indicating the index of a predefined codeword in the codebook. We analyze interference to the PU receiver and propose an algorithm to design a beamforming vector considering an error attributed to the partial CSI. The simulation shows that the analysis is quite accurate and that the beamforming vector, designed according to the proposed algorithm, keeps interference to PU below a predefined level while taking into account the error owing to the partial CSI. By using the proposed scheme, the CR system can become more robust against errors attributed to the partial CSI.
AB - This paper focuses on a downlink beamforming problem in the cognitive radio (CR) communication system where primary users (PU) coexist with secondary users (SU). It is assumed that the SU transmitter has multiple antennas and transmits data to another SU's single-antenna receiver using the beamforming technique. By properly designing a beamforming vector, SU can maximize its channel gain while maintaining an interference with PU below a predefined level. In order to construct an optimal beamforming vector, the SU transmitter requires knowledge of the downlink channel information of both PU and SU receivers sent on the feedback channel. However, it is impractical to assume that the transmitter has the perfect channel state information (CSI) considering the tremendous feedback overhead. One way to tackle this feedback overhead problem is to use a finite number of feedback bits indicating the index of a predefined codeword in the codebook. We analyze interference to the PU receiver and propose an algorithm to design a beamforming vector considering an error attributed to the partial CSI. The simulation shows that the analysis is quite accurate and that the beamforming vector, designed according to the proposed algorithm, keeps interference to PU below a predefined level while taking into account the error owing to the partial CSI. By using the proposed scheme, the CR system can become more robust against errors attributed to the partial CSI.
KW - Beamforming
KW - Cognitive Radio
KW - Finite Rate Feedback
KW - RVQ
UR - http://www.scopus.com/inward/record.url?scp=84857222445&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84857222445&partnerID=8YFLogxK
U2 - 10.1109/GLOCOM.2011.6134381
DO - 10.1109/GLOCOM.2011.6134381
M3 - Conference contribution
AN - SCOPUS:84857222445
SN - 9781424492688
T3 - GLOBECOM - IEEE Global Telecommunications Conference
BT - 2011 IEEE Global Telecommunications Conference, GLOBECOM 2011
T2 - 54th Annual IEEE Global Telecommunications Conference: "Energizing Global Communications", GLOBECOM 2011
Y2 - 5 December 2011 through 9 December 2011
ER -