6,281 research outputs found
Energy-Efficient NOMA Enabled Heterogeneous Cloud Radio Access Networks
Heterogeneous cloud radio access networks (H-CRANs) are envisioned to be
promising in the fifth generation (5G) wireless networks. H-CRANs enable users
to enjoy diverse services with high energy efficiency, high spectral
efficiency, and low-cost operation, which are achieved by using cloud computing
and virtualization techniques. However, H-CRANs face many technical challenges
due to massive user connectivity, increasingly severe spectrum scarcity and
energy-constrained devices. These challenges may significantly decrease the
quality of service of users if not properly tackled. Non-orthogonal multiple
access (NOMA) schemes exploit non-orthogonal resources to provide services for
multiple users and are receiving increasing attention for their potential of
improving spectral and energy efficiency in 5G networks. In this article a
framework for energy-efficient NOMA H-CRANs is presented. The enabling
technologies for NOMA H-CRANs are surveyed. Challenges to implement these
technologies and open issues are discussed. This article also presents the
performance evaluation on energy efficiency of H-CRANs with NOMA.Comment: This work has been accepted by IEEE Network. Pages 18, Figure
Full-Duplex MIMO Relaying Powered by Wireless Energy Transfer
We consider a full-duplex decode-and-forward system, where the wirelessly
powered relay employs the time-switching protocol to receive power from the
source and then transmit information to the destination. It is assumed that the
relay node is equipped with two sets of antennas to enable full-duplex
communications. Three different interference mitigation schemes are studied,
namely, 1) optimal 2) zero-forcing and 3) maximum ratio combining/maximum ratio
transmission. We develop new outage probability expressions to investigate
delay-constrained transmission throughput of these schemes. Our analysis show
interesting performance comparisons of the considered precoding schemes for
different system and link parameters.Comment: Accepted for IEEE International Workshop on Signal Processing
Advances in Wireless Communications (SPAWC 2015), Invited pape
Layered Steered SpaceāTime-Spreading-Aided Generalized MC DS-CDMA
AbstractāWe present a novel trifunctional multiple-inputā multiple-output (MIMO) scheme that intrinsically amalgamates spaceātime spreading (STS) to achieve a diversity gain and a Vertical Bell Labs layered spaceātime (V-BLAST) scheme to attain a multiplexing gain in the context of generalized multicarrier direct-sequence code-division multiple access (MC DS-CDMA), as well as beamforming. Furthermore, the proposed system employs both time- and frequency-domain spreading to increase the number of users, which is also combined with a user-grouping technique to reduce the effects of multiuser interference
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