Title :
Robust Distributed Cognitive Relay Beamforming
Author :
Ubaidulla, P. ; Aïssa, Sonia
Author_Institution :
Phys. Sci. & Eng. Div., KAUST, Thuwal, Saudi Arabia
Abstract :
In this paper, we present a distributed relay beamformer design for a cognitive radio network in which a cognitive (or secondary) transmit node communicates with a secondary receive node assisted by a set of cognitive non-regenerative relays. The secondary nodes share the spectrum with a licensed primary user (PU) node, and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. The proposed robust cognitive relay beamformer design seeks to minimize the total relay transmit power while ensuring that the transceiver signal-to-interference-plus-noise ratio and PU interference constraints are satisfied. The proposed design takes into account a parameter of the error in the channel state information (CSI) to render the performance of the beamformer robust in the presence of imperfect CSI. Though the original problem is non-convex, we show that the proposed design can be reformulated as a tractable convex optimization problem that can be solved efficiently. Numerical results are provided and illustrate the performance of the proposed designs for different network operating conditions and parameters.
Keywords :
array signal processing; channel allocation; cognitive radio; convex programming; interference (signal); network operating systems; radio transceivers; receiving antennas; transmitting antennas; PU interference constraints; PU node; channel state information; cognitive nodes; cognitive nonregenerative relays; cognitive radio network; cognitive transmit node; distributed relay beamformer design; imperfect CSI; licensed primary user node; network operating conditions; network operating parameters; receive antenna; robust cognitive relay beamformer design; robust distributed cognitive relay beamforming; secondary nodes; secondary receive node; secondary transmit node; total relay transmit power; tractable convex optimization problem; transceiver signal-to-interference-plus-noise ratio; transmit antenna; Array signal processing; Cognitive radio; Interference; Relays; Robustness; Signal to noise ratio; Uncertainty;
Conference_Titel :
Vehicular Technology Conference (VTC Spring), 2012 IEEE 75th
Conference_Location :
Yokohama
Print_ISBN :
978-1-4673-0989-9
Electronic_ISBN :
1550-2252
DOI :
10.1109/VETECS.2012.6239948