English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In this paper, we study the optimal secondary-link beamforming pattern thatbalances between the SU's throughput and the interference it causes to PUs inMIMO cognitive radio networks. In particular, we aim to maximize the throughputof the SU, while keeping the interference temperature at the primary receiversbelow a certain threshold.  Unlike traditional MIMO systems, SUs may not have the luxury of knowing thechannel state information (CSI) on the links to PUs. This presents a keychallenge for a secondary transmitter to steer interference away from primaryreceivers. In this paper, we consider three scenarios, namely when thesecondary transmitter has complete, partial, or no knowledge about the channelsto the primary receivers. In particular, when complete CSI is not available,the interference-temperature constraints are to be satisfied with highprobability, thus resulting in chance constraints that are typically hard todeal with. Our contribution is fourfold. First, by analyzing the distributionalcharacteristics of MIMO channels, we propose a unified homogeneous QCQPformulation that can be applied to all three scenarios. The homogeneous QCQPformulation, though non-convex, is amenable to semidefinite programming (SDP)relaxation methods. Secondly, we show that the SDP relaxation admits no gapwhen the number of primary links is no larger than two. Thirdly, we propose arandomized polynomial-time algorithm for constructing a near-optimal solutionto the QCQP problem when there are more than two primary links. Finally, weshow that when the secondary transmitter has no CSI on the links to primaryreceivers, the optimal solution to the QCQP problem can be found by a simplematrix eigenvalue-eigenvector computation, which can be done much moreefficiently than solving the QCQP directly.

Optimal Spectrum Sharing in MIMO Cognitive Radio Networks via Semidefinite Programming