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 amplify-and-forward (AF) schemes in two-hopone-way relay networks. In particular, we consider the multigroup multicasttransmission between long-distance users. Given that perfect channel stateinformation is perceived, our goal is to design the AF process so that themax-min-fair (MMF) signal-to-interference-plus-noise ratio (SINR) is optimizedsubject to generalized power constraints. We propose a rank-two beamformedAlamouti (BFA) AF scheme and formulate the corresponding AF design problem as a\emph{two-variable} fractional quadratically-constrained quadratic program(QCQP), which is further tackled by the semidefinite relaxation (SDR)technique. We analyze the approximation quality of two-variable fractional SDRsunder the Gaussian randomization algorithm. These results are fundamentally newand reveal that the proposed BFA AF scheme can outperform the traditional BF AFscheme, especially when there are many users in the system or many generalizedpower constraints in the problem formulation. From a practical perspective, theBFA AF scheme offers two degrees of freedom (DoFs) in beamformer design, asopposed to the one DoF offered by the BF AF scheme, to improve the receivers'SINR. In the latter part of this paper, we demonstrate how this extra DoF leadsto provable performance gains by considering two special cases of multicasting,where the AF process is shown to employ a special structure. The numericalsimulations further validate that the proposed BFA AF scheme outperforms the BFAF scheme and works well for large-scale relay systems.

Semidefinite Relaxation and Approximation Analysis of a Beamformed Alamouti Scheme for Relay Beamforming Networks