407 research outputs found
Fronthaul-Constrained Cloud Radio Access Networks: Insights and Challenges
As a promising paradigm for fifth generation (5G) wireless communication
systems, cloud radio access networks (C-RANs) have been shown to reduce both
capital and operating expenditures, as well as to provide high spectral
efficiency (SE) and energy efficiency (EE). The fronthaul in such networks,
defined as the transmission link between a baseband unit (BBU) and a remote
radio head (RRH), requires high capacity, but is often constrained. This
article comprehensively surveys recent advances in fronthaul-constrained
C-RANs, including system architectures and key techniques. In particular, key
techniques for alleviating the impact of constrained fronthaul on SE/EE and
quality of service for users, including compression and quantization,
large-scale coordinated processing and clustering, and resource allocation
optimization, are discussed. Open issues in terms of software-defined
networking, network function virtualization, and partial centralization are
also identified.Comment: 5 Figures, accepted by IEEE Wireless Communications. arXiv admin
note: text overlap with arXiv:1407.3855 by other author
Towards 6G Evolution: Three Enhancements, Three Innovations, and Three Major Challenges
Over the past few decades, wireless communication has witnessed remarkable
growth, experiencing several transformative changes. This article aims to
provide a comprehensive overview of wireless communication technologies, from
the foundations to the recent wireless advances. Specifically, we take a
neutral look at the state-of-the-art technologies for 5G and the ongoing
evolutions towards 6G, reviewing the recommendations of the International
Mobile Communication vision for 2030 (IMT-2030). We first highlight specific
features of IMT 2030, including three IMT-2020 extensions (URLLC+, eMBB+, and
mMTC+) and three new innovations (Ubiquitous connectivity and integrating the
new capabilities of sensing & AI with communication functionality). Then, we
delve into three major challenges in implementing 6G, along with global
standardization efforts. Besides, a proof of concept is provided by
demonstrating terahertz (THz) signal transmission using Orbital Angular
Momentum (OAM) multiplexing, which is one of the potential candidates for 6G
and beyond. To inspire further potential research, we conclude by identifying
research opportunities and future visions on IMT-2030 recommendations.Comment: 8 pages, 4 figures, 1 tabl
Emerging Technologies and Research Challenges for 5G Wireless Networks
As the take-up of Long Term Evolution (LTE)/4G cellular accelerates, there is
increasing interest in technologies that will define the next generation (5G)
telecommunication standard. This paper identifies several emerging technologies
which will change and define the future generations of telecommunication
standards. Some of these technologies are already making their way into
standards such as 3GPP LTE, while others are still in development.
Additionally, we will look at some of the research problems that these new
technologies pose.Comment: Accepted for publication in IEEE Wireless Communications April 201
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
A short survey on next generation 5G wireless networks
Current 4G - the fourth-generation wireless communication, which exists in most countries, represents an advance of the previous 3 generation wireless communication. However, there are some challenges and limitations, associated with an explosion of wireless devices, which cannot be accommodated by 4G. Increasing the proliferation of smart devices, the development of new multimedia applications, and the growing demand for high data rates are among the main problems of the existing 4G system. As a solution, the wireless system designers have started research on the fifth-generation wireless systems. 5G will be the paradigm shift that could provide with ultra-high data rate, low latency, an increase of the base station capacity, and the improved quality of services. This paper is a review of the changes through the evolution of existing cellular networks toward 5G. It represented a comprehensive study associated with 5G, requirements for 5G, its advantages, and challenges. We will explain the architecture changes – radio access network (RAN), air interfaces, smart antennas, cloud RAN, and HetNet. Furthermore, it discussed physical layer technologies, which include new channel modes estimation, new antenna design, and MIMO technologies. Also, it discussed MAC layer protocols. The article included three kinds of technologies: heterogeneous networks, massive multiple-input and output, and millimeter-wave. Finally, it explained the applications, supported by 5G, new features, various possibilities, and predictions
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