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/

Zendy Plus

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

Zendy Tools

Zendy Open

In this paper, a general cognitive radio system consisting of a set of userswith different level of spectrum access including two primary transceivers andseveral types of secondary users is considered. It is assumed that twosecondary users operate based on an underlay model at the same frequencybandwidth and at the same time as the primary users based on a multiple accessbroadcast channel (MABC) bidirectional beamforming scheme. Other secondaryusers provide a relaying service to the primary users in exchange for theopportunity to send their messages towards their own destinations for a fixedportion of the communication cycle. In addition, it is assumed that someinterferers are active during the communication cycle and cause interferencefor the network. Furthermore, it is assumed that only partial channel stateinformation (CSI) between interferers and other nodes in the network isavailable.  We provide a robust optimization method against imperfection on theinterferers' CSI to maximize the joint primary and secondary{signal-to-interference-plus-noise-ratio (SINR)} with the assumption of limitedavailable power at the secondary relays. An amplify-and-forward (AF) relayingscheme is deployed at the secondary relays and the optimal beamforming isobtained using second order convex programming (SOCP) method. The simulationresults show the performance of the proposed beamforming method against theexistence of interferers, and demonstrate the effectiveness of our robustmethod against uncertainty in knowledge of interferers' CSIs.

Optimal Relaying Beamforming in Multiple Access Broadcast Channel (MABC) Bidirectional Cognitive Radio Networks in Presence of Interferers