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Journal ArticleDOI

A Survey of the Challenges, Opportunities and Use of Multiple Antennas in Current and Future 5G Small Cell Base Stations

TL;DR: A state-of-the-art review of the literature to show how researchers are using and considering the use of multiple antennas in small cells and insights into the design challenges in such possible future networks are provided.
Abstract: Small cell base stations (SBSs) and multiple antennas are seen as fundamental technologies in the emergence of the next generation [i.e., 5th generation (5G)] of cellular wireless technology. This paper provides a comprehensive survey of literature relating to the applications and challenges associated with using multiple antennas in SBSs. The use of multiple antenna techniques in conventional wireless base stations has undergone much study and is widespread. With heterogeneity in current networks and a furthering of this theme together with greater densification expected in 5G systems, their use in SBSs is at an evolutionary stage. In this paper, unique design challenges associated with size, cost, and performance in SBSs are presented. We present a clear understanding of this increasingly important research area, identifying a clear classification of use and design guidelines. We present a state-of-the-art review of the literature to show how researchers are using and considering the use of multiple antennas in small cells. Attention is given to current generation networks, and with SBSs being a dominant technology necessary for 5G, we also provide insights into the design challenges in such possible future networks.
Citations
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Journal ArticleDOI
TL;DR: A literature review on recent applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks, and the joint optimization of the IRS’s phase control and the transceivers’ transmission control in different network design problems, e.g., rate maximization and power minimization problems.
Abstract: This paper presents a literature review on recent applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks. Conventionally, the network optimization has been limited to transmission control at two endpoints, i.e., end users and network controller. The fading wireless channel is uncontrollable and becomes one of the main limiting factors for performance improvement. The IRS is composed of a large array of scattering elements, which can be individually configured to generate additional phase shifts to the signal reflections. Hence, it can actively control the signal propagation properties in favor of signal reception, and thus realize the notion of a smart radio environment. As such, the IRS’s phase control, combined with the conventional transmission control, can potentially bring performance gain compared to wireless networks without IRS. In this survey, we first introduce basic concepts of the IRS and the realizations of its reconfigurability. Then, we focus on applications of the IRS in wireless communications. We overview different performance metrics and analytical approaches to characterize the performance improvement of IRS-assisted wireless networks. To exploit the performance gain, we discuss the joint optimization of the IRS’s phase control and the transceivers’ transmission control in different network design problems, e.g., rate maximization and power minimization problems. Furthermore, we extend the discussion of IRS-assisted wireless networks to some emerging use cases. Finally, we highlight important practical challenges and future research directions for realizing IRS-assisted wireless networks in beyond 5G communications.

642 citations


Cites background from "A Survey of the Challenges, Opportu..."

  • ...For wireless network operators, the ever-increasing traffic demand can be fulfilled by deploying energy-efficient small cells in a dense network or using multiple antennas at the BS to increase spectrum efficiency [3]....

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Journal ArticleDOI
TL;DR: The suitability of hybrid beamforming methods, both, existing and proposed till first quarter of 2017, are explored, and the exciting future challenges in this domain are identified.
Abstract: The increasing wireless data traffic demands have driven the need to explore suitable spectrum regions for meeting the projected requirements. In the light of this, millimeter wave (mmWave) communication has received considerable attention from the research community. Typically, in fifth generation (5G) wireless networks, mmWave massive multiple-input multiple-output (MIMO) communications is realized by the hybrid transceivers which combine high dimensional analog phase shifters and power amplifiers with lower-dimensional digital signal processing units. This hybrid beamforming design reduces the cost and power consumption which is aligned with an energy-efficient design vision of 5G. In this paper, we track the progress in hybrid beamforming for massive MIMO communications in the context of system models of the hybrid transceivers’ structures, the digital and analog beamforming matrices with the possible antenna configuration scenarios and the hybrid beamforming in heterogeneous wireless networks. We extend the scope of the discussion by including resource management issues in hybrid beamforming. We explore the suitability of hybrid beamforming methods, both, existing and proposed till first quarter of 2017, and identify the exciting future challenges in this domain.

505 citations


Cites background from "A Survey of the Challenges, Opportu..."

  • ...The paper [66] reviews state-of-the-art literatures related to the applications and challenges associated with using multiple antennas in SBSs....

    [...]

Journal ArticleDOI
TL;DR: An extensive overview of the recent advances and research challenges in intelligent management techniques and backhaul solutions in the last five years for the combination of UDNs and other enabling technologies that offers the visions of 5G is presented.
Abstract: Recently, to address the astonishing capacity requirement of 5G, researchers are investigating the possibility of combining different technologies with ultra-dense networks (UDNs). However, the ultra-dense deployment of small cells in the coverage area of conventional macrocells known as UDNs introduces new technical challenges such as severe interference, unfairness in radio resource sharing, unnecessary handover, a significant increase in energy consumption, and degraded quality-of-service (QoS). To overcome these challenges and achieve the performance requirements in 5G, there is a need to combine UDNs with other 5G enabling technologies and then, design intelligent management techniques for better performance of the overall networks. Hence, in this paper, we present a comprehensive survey on different generations of wireless networks, 5G new radio (NR) standards, 5G enabling technologies and the importance of combining UDNs with other 5G technologies. Also, we present an extensive overview of the recent advances and research challenges in intelligent management techniques and backhaul solutions in the last five years for the combination of UDNs and other enabling technologies that offers the visions of 5G. We summarise the mathematical tools widely exploited in solving these problems and the performance metrics used to evaluate the intelligent management algorithms. Moreover, we classify various intelligent management algorithms according to the adopted enabling technologies, benefits, challenges addressed, mathematical tools and performance metrics used. Finally, we summarise the open research challenges, provide design guidelines and potential research directions for the development of intelligent management techniques and backhaul solutions for the combination of UDNs and other 5G technologies.

92 citations


Cites background from "A Survey of the Challenges, Opportu..."

  • ...• Benefits of Deploying Small Cells: These benefits are summarised below: (i) Improved coverage: The deployment of small cells in outdoor, or indoor environments would cover the coverage holes of macrocells due to the close proximity of the transmitters (small cells) and the receivers (SUEs) [6], [14], [18], [89]–[91]....

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  • ...The uplink co-tier interference is caused by surrounding, co-located SUEs creating interference to nearby SBSs while the downlink co-tier interference is caused by the SBS transmission interfering with neighbouring SUEs [170]....

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Journal ArticleDOI
TL;DR: An innovative methodological paradigm is proposed for the design of unconventional antenna systems for future 5G base stations through a multiobjective antenna-shape optimization combined with a subarraying technique based on a new single-objective integer-coded genetic algorithm able to intrinsically handle constraints on the cluster shapes/types.
Abstract: An innovative methodological paradigm is proposed for the design of unconventional antenna systems for future 5G base stations. In such a codesign strategy, the antenna element (a spline-shaped patch embedded in a finite-array model ) and the overall irregularly clustered-array layout are simultaneously synthesized through a multiobjective antenna-shape optimization combined with a subarraying technique based on a new single-objective integer-coded genetic algorithm able to intrinsically handle constraints on the cluster shapes/types. Selected numerical examples, drawn from an exhaustive design process, are presented to assess the advantages and the effectiveness of the proposed co-design scheme in view of the final manufacturing of 5G base stations thanks to its capability to take into account the impact of mutual coupling, nonideal antenna patterns, and implementation limitations.

66 citations


Cites background from "A Survey of the Challenges, Opportu..."

  • ...2738065 widely agreed [3] that 5G base station antennas will have to...

    [...]

  • ...Active electronically scanned arrays (AESAs) [6], [7] are a promising technology to address a 5G base station antenna design [3], [8]–[12]....

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  • ...THE FUTURE generation of mobile wireless technologies, commonly labeled as “5G,” is expected to deliver multigigabit-per-second data rates while minimizing costs, connection latencies, and power consumption [1]–[3]....

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  • ..., impedance matching, isolation from surrounding elements, polarization ellipticity, gain, and beamwidth) must be fit [3], [11], [13]....

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  • ...3Although 5G standards have not yet been officially published, a set of frequency bands have already been released [27], and guidelines regarding the envisaged performance and indicators to be optimized for 3D beamforming, active antenna, and massive MIMO systems have already been discussed [3], [11], [13], [28]....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors present a literature review on recent applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks, and discuss the joint optimization of the IRS's phase control and the transceivers' transmission control in different network design problems, e.g., rate maximization and power minimization problems.
Abstract: This paper presents a literature review on recent applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks. Conventionally, the network optimization has been limited to transmission control at two endpoints, i.e., end users and network controller. The fading wireless channel is uncontrollable and becomes one of the main limiting factors for performance improvement. The IRS is composed of a large array of scattering elements, which can be individually configured to generate additional phase shifts to the signal reflections. Hence, it can actively control the signal propagation properties in favor of signal reception, and thus realize the notion of a smart radio environment. As such, the IRS's phase control, combined with the conventional transmission control, can potentially bring performance gain compared to wireless networks without IRS. In this survey, we first introduce basic concepts of the IRS and the realizations of its reconfigurability. Then, we focus on applications of the IRS in wireless communications. We overview different performance metrics and analytical approaches to characterize the performance improvement of IRS-assisted wireless networks. To exploit the performance gain, we discuss the joint optimization of the IRS's phase control and the transceivers' transmission control in different network design problems, e.g.,~rate maximization and power minimization problems. Furthermore, we extend the discussion of IRS-assisted wireless networks to some emerging use cases. Finally, we highlight important practical challenges and future research directions for realizing IRS-assisted wireless networks in beyond 5G communications.

62 citations

References
More filters
Journal ArticleDOI
Siavash Alamouti1
TL;DR: This paper presents a simple two-branch transmit diversity scheme that provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas.
Abstract: This paper presents a simple two-branch transmit diversity scheme. Using two transmit antennas and one receive antenna the scheme provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas. It is also shown that the scheme may easily be generalized to two transmit antennas and M receive antennas to provide a diversity order of 2M. The new scheme does not require any bandwidth expansion or any feedback from the receiver to the transmitter and its computation complexity is similar to MRRC.

13,706 citations


"A Survey of the Challenges, Opportu..." refers background in this paper

  • ...Perhaps the most simplest of these, and therefore applicable for a SBS because of its low complexity, is the Alamouti space time code scheme [22]....

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  • ...High correlation between elements will lead to poorer performance for systems employing antenna diversity schemes such as receive diversity and transmit diversity through space time transmit-diversity (STTD) Alamouti codes [22]....

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Journal ArticleDOI
TL;DR: This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.
Abstract: What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

7,139 citations


"A Survey of the Challenges, Opportu..." refers background in this paper

  • ...Recent most vision papers on 5G also point out small cells as the key technology to achieve 5G requirements [1], [2]....

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  • ...There is also an increasing pressure to use advanced antenna techniques, to maximize spectral efficiency (SE), to cope with the relentless demand for increased data rates [1], [9]....

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  • ...5G) to increase the network capacity and to provide required data rates [1]....

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  • ...It is well recognized that a key challenge in the adoption of HetNets is cross tier interference between the small cell and macrocell network [1], [40], [43] particularly when the small cell networks share the same frequency band as the surrounding macrocell network....

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Journal ArticleDOI
TL;DR: An overview of beamforming from a signal-processing perspective is provided, with an emphasis on recent research.
Abstract: An overview of beamforming from a signal-processing perspective is provided, with an emphasis on recent research. Data-independent, statistically optimum, adaptive, and partially adaptive beamforming are discussed. Basic notation, terminology, and concepts are included. Several beamformer implementations are briefly described. >

4,122 citations


"A Survey of the Challenges, Opportu..." refers background in this paper

  • ...Beamforming at the SBS can be provided on both uplink [37] and downlink [38]....

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Journal ArticleDOI
TL;DR: The technical and business arguments for femtocells are overview and the state of the art on each front is described and the technical challenges facing femtocell networks are described and some preliminary ideas for how to overcome them are given.
Abstract: The surest way to increase the system capacity of a wireless link is by getting the transmitter and receiver closer to each other, which creates the dual benefits of higher-quality links and more spatial reuse. In a network with nomadic users, this inevitably involves deploying more infrastructure, typically in the form of microcells, hot spots, distributed antennas, or relays. A less expensive alternative is the recent concept of femtocells - also called home base stations - which are data access points installed by home users to get better indoor voice and data coverage. In this article we overview the technical and business arguments for femtocells and describe the state of the art on each front. We also describe the technical challenges facing femtocell networks and give some preliminary ideas for how to overcome them.

3,298 citations


"A Survey of the Challenges, Opportu..." refers background in this paper

  • ...FBSs are typically installed impromptu in the residential domain or small office/home Office (SOHO) and provide wireless cellular access to a closed or open group of subscribers as configured by the subscriber and/or the service provider [5]....

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  • ...They are seen as an alternative to traditional MBSs for increasing coverage, quality of service (QoS), capacity and energy efficiency (EE) [5], [6]....

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Journal ArticleDOI
R.H. Walden1
TL;DR: The state-of-the-art of ADCs is surveyed, including experimental converters and commercially available parts, and the distribution of resolution versus sampling rate provides insight into ADC performance limitations.
Abstract: Analog-to-digital converters (ADCs) are ubiquitous, critical components of software radio and other signal processing systems. This paper surveys the state-of-the-art of ADCs, including experimental converters and commercially available parts. The distribution of resolution versus sampling rate provides insight into ADC performance limitations. At sampling rates below 2 million samples per second (Gs/s), resolution appears to be limited by thermal noise. At sampling rates ranging from /spl sim/2 Ms/s to /spl sim/4 giga samples per second (Gs/s), resolution falls off by /spl sim/1 bit for every doubling of the sampling rate. This behavior may be attributed to uncertainty in the sampling instant due to aperture jitter. For ADCs operating at multi-Gs/s rates, the speed of the device technology is also a limiting factor due to comparator ambiguity. Many ADC architectures and integrated circuit technologies have been proposed and implemented to push back these limits. The trend toward single-chip ADCs brings lower power dissipation. However, technological progress as measured by the product of the ADC resolution (bits) times the sampling rate is slow. Average improvement is only /spl sim/1.5 bits for any given sampling frequency over the last six-eight years.

2,220 citations


"A Survey of the Challenges, Opportu..." refers background in this paper

  • ...In addition, as the sampling rate of such ADCs increases so does the inaccuracy of the conversion due to aperture jitter [68]....

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