Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges
05 Feb 2014-Vol. 102, Iss: 3, pp 366-385
TL;DR: Measurements and capacity studies are surveyed to assess mmW technology with a focus on small cell deployments in urban environments and it is shown that mmW systems can offer more than an order of magnitude increase in capacity over current state-of-the-art 4G cellular networks at current cell densities.
Abstract: Millimeter-wave (mmW) frequencies between 30 and 300 GHz are a new frontier for cellular communication that offers the promise of orders of magnitude greater bandwidths combined with further gains via beamforming and spatial multiplexing from multielement antenna arrays. This paper surveys measurements and capacity studies to assess this technology with a focus on small cell deployments in urban environments. The conclusions are extremely encouraging; measurements in New York City at 28 and 73 GHz demonstrate that, even in an urban canyon environment, significant non-line-of-sight (NLOS) outdoor, street-level coverage is possible up to approximately 200 m from a potential low-power microcell or picocell base station. In addition, based on statistical channel models from these measurements, it is shown that mmW systems can offer more than an order of magnitude increase in capacity over current state-of-the-art 4G cellular networks at current cell densities. Cellular systems, however, will need to be significantly redesigned to fully achieve these gains. Specifically, the requirement of highly directional and adaptive transmissions, directional isolation between links, and significant possibilities of outage have strong implications on multiple access, channel structure, synchronization, and receiver design. To address these challenges, the paper discusses how various technologies including adaptive beamforming, multihop relaying, heterogeneous network architectures, and carrier aggregation can be leveraged in the mmW context.
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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
Cites background from "Millimeter-Wave Cellular Wireless N..."
...Marzetta was instrumental in articulating a vision in which the number of antennas increased by more than an order of magnitude, first in a 2007 presentation [89] with the details formalized in a landmark paper [90]....
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TL;DR: This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.
Abstract: Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.
2,380 citations
Cites background from "Millimeter-Wave Cellular Wireless N..."
...A major outstanding issue is characterizing the joint probabilities in outage between links from different cells, which is critical in assessing the benefits of macro-diversity [65], [66]....
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TL;DR: Detailed spatial statistical models of the channels are derived and it is found that, even in highly non-line-of-sight environments, strong signals can be detected 100-200 m from potential cell sites, potentially with multiple clusters to support spatial multiplexing.
Abstract: With the severe spectrum shortage in conventional cellular bands, millimeter wave (mmW) frequencies between 30 and 300 GHz have been attracting growing attention as a possible candidate for next-generation micro- and picocellular wireless networks. The mmW bands offer orders of magnitude greater spectrum than current cellular allocations and enable very high-dimensional antenna arrays for further gains via beamforming and spatial multiplexing. This paper uses recent real-world measurements at 28 and 73 GHz in New York, NY, USA, to derive detailed spatial statistical models of the channels and uses these models to provide a realistic assessment of mmW micro- and picocellular networks in a dense urban deployment. Statistical models are derived for key channel parameters, including the path loss, number of spatial clusters, angular dispersion, and outage. It is found that, even in highly non-line-of-sight environments, strong signals can be detected 100-200 m from potential cell sites, potentially with multiple clusters to support spatial multiplexing. Moreover, a system simulation based on the models predicts that mmW systems can offer an order of magnitude increase in capacity over current state-of-the-art 4G cellular networks with no increase in cell density from current urban deployments.
2,102 citations
Cites background from "Millimeter-Wave Cellular Wireless N..."
...It should be noted that the capacity numbers reported in [9], which were based on an earlier version...
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...widths are much wider than today’s cellular networks [4]–[9]....
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TL;DR: An overview of 5G research, standardization trials, and deployment challenges is provided, with research test beds delivering promising performance but pre-commercial trials lagging behind the desired 5G targets.
Abstract: There is considerable pressure to define the key requirements of 5G, develop 5G standards, and perform technology trials as quickly as possible. Normally, these activities are best done in series but there is a desire to complete these tasks in parallel so that commercial deployments of 5G can begin by 2020. 5G will not be an incremental improvement over its predecessors; it aims to be a revolutionary leap forward in terms of data rates, latency, massive connectivity, network reliability, and energy efficiency. These capabilities are targeted at realizing high-speed connectivity, the Internet of Things, augmented virtual reality, the tactile internet, and so on. The requirements of 5G are expected to be met by new spectrum in the microwave bands (3.3-4.2 GHz), and utilizing large bandwidths available in mm-wave bands, increasing spatial degrees of freedom via large antenna arrays and 3-D MIMO, network densification, and new waveforms that provide scalability and flexibility to meet the varying demands of 5G services. Unlike the one size fits all 4G core networks, the 5G core network must be flexible and adaptable and is expected to simultaneously provide optimized support for the diverse 5G use case categories. In this paper, we provide an overview of 5G research, standardization trials, and deployment challenges. Due to the enormous scope of 5G systems, it is necessary to provide some direction in a tutorial article, and in this overview, the focus is largely user centric, rather than device centric. In addition to surveying the state of play in the area, we identify leading technologies, evaluating their strengths and weaknesses, and outline the key challenges ahead, with research test beds delivering promising performance but pre-commercial trials lagging behind the desired 5G targets.
1,659 citations
TL;DR: Experimental measurements and empirically-based propagation channel models for the 28, 38, 60, and 73 GHz mmWave bands are presented, using a wideband sliding correlator channel sounder with steerable directional horn antennas at both the transmitter and receiver from 2011 to 2013.
Abstract: The relatively unused millimeter-wave (mmWave) spectrum offers excellent opportunities to increase mobile capacity due to the enormous amount of available raw bandwidth. This paper presents experimental measurements and empirically-based propagation channel models for the 28, 38, 60, and 73 GHz mmWave bands, using a wideband sliding correlator channel sounder with steerable directional horn antennas at both the transmitter and receiver from 2011 to 2013. More than 15,000 power delay profiles were measured across the mmWave bands to yield directional and omnidirectional path loss models, temporal and spatial channel models, and outage probabilities. Models presented here offer side-by-side comparisons of propagation characteristics over a wide range of mmWave bands, and the results and models are useful for the research and standardization process of future mmWave systems. Directional and omnidirectional path loss models with respect to a 1 m close-in free space reference distance over a wide range of mmWave frequencies and scenarios using directional antennas in real-world environments are provided herein, and are shown to simplify mmWave path loss models, while allowing researchers to globally compare and standardize path loss parameters for emerging mmWave wireless networks. A new channel impulse response modeling framework, shown to agree with extensive mmWave measurements over several bands, is presented for use in link-layer simulations, using the observed fact that spatial lobes contain multipath energy that arrives at many different propagation time intervals. The results presented here may assist researchers in analyzing and simulating the performance of next-generation mmWave wireless networks that will rely on adaptive antennas and multiple-input and multiple-output (MIMO) antenna systems.
1,417 citations
Cites methods from "Millimeter-Wave Cellular Wireless N..."
...The floating intercept model parameters for the 28 and 73 GHz campaigns are slightly different here than those described in [40], due to an updated PDP thresholding algorithm that uses a more stringent 5 dB SNR threshold, and by separating the TX-RX path loss data points by RX antenna...
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...A more detailed description of how the directional measurements were aggregated together to create omnidirectional models similar to those in [39] and [40] was presented in [38]....
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References
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10 Jun 2014
TL;DR: The potential of utilizing spatial filtering and beam combining to significantly improve received signal levels and link margins at millimeter-wave frequencies is demonstrated.
Abstract: The performance of multi-beam antenna equal gain combining for improving signal quality in future millimeter-wave cellular systems is evaluated in this article Employing experimental data obtained from 28 GHz and 73 GHz propagation measurements in the dense urban environment of New York City, we present the impact of coherent bi-beam, tri-beam and quad-beam combining on path loss and shadow factors The results reveal that a maximum of 249 dB improvement in path loss at 28 GHz and 348 dB at 73 GHz for 100 m T-R (transmitter-receiver) separation distances can be achieved via combining the strongest four received signals from distinct beams, when compared to the case of signals at the receiver with randomly pointed beams Comparable path loss values are achieved at both 28 and 73 GHz bands This paper demonstrates the potential of utilizing spatial filtering and beam combining to significantly improve received signal levels and link margins at millimeter-wave frequencies
76 citations
Book•
15 Dec 2008
TL;DR: In this paper, the authors provide an application-focused reference on millimetre wave antennas for Gigabit wireless communications, and provide a practical guide to integrated antennas for specific configurations requirements.
Abstract: Complete and comprehensive application-focused reference on millimetre wave antennas Millimetre Wave Antennas for Gigabit Wireless Communications covers a vast wealth of material with a strong focus on the current design and analysis principles of millimetre wave antennas for wireless devices. It provides practising engineers with the design rules and considerations required in designing antennas for the terminal. The authors include coverage of new configurations with advanced angular and frequency filtering characteristics, new design and analysis techniques, and methods for filter miniaturization. The book reviews up-to-date research results and utilizes numerous design examples to emphasize computer analysis and synthesis whilst also discussing the applications of commercially available software. Key Features: Advanced and up-to-date treatment of one of the fastest growing fields of wireless communications Covers topics such as Gigabit wireless communications and its required antennas, passive and active antenna design and analysis techniques, multibeam antennas and MIMO, IEEE 802.15.3c, WiMedia, and advanced materials and technologies Offers a practical guide to integrated antennas for specific configurations requirements Addresses a number of complex, real-world problems that system and antenna engineers are going to face in millimetre-wave communications industry and provides solutions Contains detailed design examples, drawings and predicted performance This book is an invaluable tool for antenna professionals (engineers, designers, and developers), microwave professionals, wireless communication system professionals, and industries with microwave and millimetre wave research projects. Advanced students and researchers working in the field of millimetre wave engineering will also find this book very useful.
74 citations
01 Dec 2013
TL;DR: This work investigates the challenges in deploying an anchor-booster based HetNet with mmWave capable booster cells and shows that due to the channel characteristics of mmWave bands, there could be a mismatch between the discoverable coverage area of booster cell at mmWave band and the actual supportable Coverage mismatch.
Abstract: Communication in millimeter wave (mmWave) spectrum has gained an increasing interests for tackling the spectrum crunch problem and meeting the high network capacity demand in 4G and beyond. Considering the channel characteristics of mmWave bands, it can be fit into heterogeneous networks (HetNet) for boosting local-area data rate. In this paper, we investigate the challenges in deploying an anchor-booster based HetNet with mmWave capable booster cells. We show that due to the channel characteristics of mmWave bands, there could be a mismatch between the discoverable coverage area of booster cell at mmWave band and the actual supportable coverage area. Numerical results are provided in validating the observation. We suggest possible ways in addressing the coverage mismatch problem. This work provides insights on the deployment and implementation challenges in mmWave capable HetNets.
73 citations
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...This ‘‘spatial searching’’ may delay BS detection in handoversVa point made in a recent paper [88]....
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14 Nov 1995
TL;DR: The measurements indicate that building blockage is a major limitation on the ability to cover a particular location and provide valuable information on the coverage limitations imposed by path loss in an operational LMDS environment.
Abstract: This paper presents the results of a propagation measurement campaign at 28 GHz in Brighton Beach, Brooklyn, to investigate the performance of local multipoint distribution service (LMDS) LMDS could be used to provide wireless access to fixed networks providing services ranging from one-way video distribution and telephony to fully-interactive switched broadband multimedia applications These measurements provide valuable information on the coverage limitations imposed by path loss in an operational LMDS environment The measurements investigated path loss characteristics and the presence of specular reflections as a function of antenna height The measurements indicate that building blockage is a major limitation on the ability to cover a particular location Strong signals were only received at locations where a line-of-sight path was available between the transmitter and receiver In addition, at many locations, the signal disappeared completely as the antenna was lowered below the roofline of a building directly between the transmitter and receiver Specular reflections were detected at many locations, but the presence of reflected signals did not significantly increase the number of locations where strong signals were received
72 citations
"Millimeter-Wave Cellular Wireless N..." refers methods in this paper
...Also, measurements in local multipoint distribution systems (LMDSs) at 28 GHzVthe prior system most close to mmW cellularVhave been inconclusive: For example, a study [76] found 80% coverage at ranges up to 1–2 km, while Seidel [77] claimed that LOS connectivity would be required....
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26 Apr 2010
TL;DR: The large amounts of bandwidth available in the millimeter (mm) wave band enable multiGigabit wireless networks with applications ranging from indoor multimedia networking to outdoor backhaul for picocellular networks, which implies that spatial multiplexing gains can be obtained even in Line of Sight (LoS) environments with antennas with moderate separation.
Abstract: The large amounts of bandwidth available in the millimeter (mm) wave band enable multiGigabit wireless networks with applications ranging from indoor multimedia networking to outdoor backhaul for picocellular networks Carrier wavelengths in this band are an order of magnitude smaller than those for existing cellular and WiFi systems, resulting in a drastically different propagation geometry Omnidirectional transmission is essentially infeasible because of the increased propagation loss at smaller wavelengths; on the other hand, highly directive transmission and reception with electronically steerable beams can be achieved using compact antenna arrays Thus, in contrast to the rich scattering environment at lower carrier frequencies, a small number of paths are dominant for directional mm wave links The small wavelength also implies that spatial multiplexing gains can be obtained even in Line of Sight (LoS), or more generally, sparse scattering, environments with antennas with moderate separation In this paper, we examine the consequences of these observations for two scenarios The first is a lamppost-based outdoor deployment, where we model fading due to ground and wall reflections, and examine MIMO techniques for combating fading The second is for spatial multiplexing for an indoor link, where we model the number of eigenmodes as a function of form factor, and examine the effect of blockage
71 citations