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 investigate multiuser diversity in interference-limitedMultiple Access (MAC) underlay cognitive channels with Line-of-Sightinterference (LoS) from the secondary to the primary network. It is shown thatfor $N$ secondary users, and assuming Rician interference channels, thesecondary sum capacity scales like$\log\left(\frac{K^{2}+K}{\mathcal{W}\left(\frac{K e^{K}}{N}\right)}\right)$,where $K$ is the $K$-factor of the Rician channels, and $\mathcal{W}(.)$ is theLambert W function. Thus, LoS interference hinders the achievable multiuserdiversity gain experienced in Rayleigh channels, where the sum capacity growslike $\log(N)$. To overcome this problem, we propose the usage of single radioElectronically Steerable Parasitic Array Radiator (ESPAR) antennas at thesecondary mobile terminals. Using ESPAR antennas, we induce artificialfluctuations in the interference channels to restore the $\log(N)$ growth rateby assigning random weights to orthogonal {\it basis patterns}. We term thistechnique as {\it Random Aerial Beamforming} (RAB). While LoS interference isoriginally a source of capacity hindrance, we show that using RAB, it canactually be exploited to improve multiuser interference diversity by boostingthe {\it effective number of users} with minimal hardware complexity.

Opportunistic Beamforming using Dumb Basis Patterns in Multiple Access Cognitive Channels