275 research outputs found
Connectivity of Underlay Cognitive Radio Networks with Directional Antennas
In cognitive radio networks (CRNs), the connectivity of secondary users (SUs)
is difficult to be guaranteed due to the existence of primary users (PUs). Most
prior studies only consider cognitive radio networks equipped with
omni-directional antennas causing high interference at SUs. We name such CRNs
with omni-directional antennas as Omn-CRNs. Compared with an omni-directional
antenna, a directional antenna can concentrate the transmitting/receiving
capability at a certain direction, consequently resulting in less interference.
In this paper, we investigate the connectivity of SUs in CRNs with directional
antennas (named as Dir-CRNs). In particular, we derive closed-form expressions
of the connectivity of SUs of both Dir-CRNs and Omn-CRNs, thus enabling
tractability. We show that the connectivity of SUs is mainly affected by two
constraints: the spectrum availability of SUs and the topological connectivity
of SUs. Extensive simulations validate the accuracy of our proposed models.
Meanwhile, we also show that Dir-CRNs can have higher connectivity than
Omn-CRNs mainly due to the lower interference, the higher spectrum availability
and the higher topological connectivity brought by directional antennas.Comment: 9 pages, a full version to appear in IEEE Transactions on Vehicular
Technology 201
Regulatory and Policy Implications of Emerging Technologies to Spectrum Management
This paper provides an overview of the policy implications of technological developments, and how these technologies can accommodate an increased level of market competition. It is based on the work carried out in the SPORT VIEWS (Spectrum Policies and Radio Technologies Viable In Emerging Wireless Societies) research project for the European Commission (FP6)spectrum, new radio technologies, UWB, SDR, cognitive radio, Telecommunications, regulation, Networks, Interconnection
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
Assessment of Cognitive Communications Interest Areas for NASA Needs and Benefits
This effort provides a survey and assessment of various cognitive communications interest areas, including node-to-node link optimization, intelligent routing/networking, and learning algorithms, and is conducted primarily from the perspective of NASA space communications needs and benefits. Areas of consideration include optimization methods, learning algorithms, and candidate implementations/technologies. Assessments of current research efforts are provided with mention of areas for further investment. Other considerations, such as antenna technologies and cognitive radio platforms, are briefly provided as well
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