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.
Citations
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TL;DR: In this paper, a random spatial model is proposed to analyze uplink and downlink signal to interference plus noise ratio distribution and mean rates corresponding to different access-backhaul and UL-DL resource allocation schemes in a self-hauled mm-wave cellular network with Poisson point process (PPP) deployment of users and BSs.
Abstract: Initial deployments of millimeter wave (mm-wave) cellular networks are likely to be enabled with self-backhauling. In this paper, we propose a random spatial model to analyze uplink (UL) and downlink (DL) signal to interference plus noise ratio distribution and mean rates corresponding to different access-backhaul and UL–DL resource allocation schemes in a self-backhauled mm-wave cellular network with Poisson point process (PPP) deployment of users and base stations (BSs). In particular, we focus on heuristic implementations of static and dynamic time division duplexing (TDD) for access links with synchronized or unsynchronized access-backhaul (SAB or UAB) time splits. We propose PPP approximations to characterize the distribution of the new types of interference encountered with dynamic TDD and UAB. These schemes offer better resource utilization than static TDD and SAB, however, potentially higher interference makes their choice non-trivial and the offered gains sensitive to different network parameters, including UL/DL traffic asymmetry, user load per BS or number of slave BSs per master BS. One can harness notable gains from UAB and/or dynamic TDD only if backhaul links are designed to have much larger throughput than the access links.
45 citations
TL;DR: A hybrid beamforming scheme based on the cross-entropy estimation with the robustness algorithm inspired by machine learning and a novel mean field game (MFG)-based massive MIMO angle control scheme to model the optimal mmWave channel optimization problem between UAVs and ground users are proposed.
Abstract: In unmanned aerial vehicle (UAV)-assisted massive multi-input multi-output (MIMO) millimeter-wave (mmWave) networks, beam-steering guarantees reliable and steady connection between flying base stations and ground users with the challenge of strict angular deviation. In this paper, we investigate a joint optimization problem of beamforming and beam-steering in the multi-UAV mmWave networks, considering line-of-sight (LoS) communication for UAVs. For the hybrid beamforming optimization of massive MIMO mmWave, we propose a hybrid beamforming scheme based on the cross-entropy estimation with the robustness algorithm inspired by machine learning, which aims to optimize the hybrid precoding matrix. For the beam-steering optimization, we propose a novel mean field game (MFG)-based massive MIMO angle control scheme to model the optimal mmWave channel optimization problem between UAVs and ground users. In addition, when dealing with the problem of initial sensitivity and difficulty to solve the partial differential equations in the MFG, we utilize reinforcement learning to achieve the mean field equilibrium, which is described as the mean field learning game algorithm. Finally, a joint beamforming and beam-steering optimization algorithm is proposed to maximize the system sum-rate. Simulation results show the significant improvements in sum-rate, energy efficiency, and spectral efficiency, which verify the effectiveness of the proposed algorithm.
45 citations
Additional excerpts
...technologies to overcome link blocking [11]....
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TL;DR: A structured CP decomposition-based channel estimation strategy aided by the spatial smoothing method is proposed, which outperforms the traditional approaches in terms of accuracy, robustness and complexity.
Abstract: We consider the channel estimation problem in millimeter wave (mmWave) multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with hybrid analog-digital architectures. Leveraging the spatial- and frequency-wideband (dual-wideband) effects in massive MIMO scenarios, we derive a spatial-frequency channel model with dual-wideband effects that incorporates the multipath parameters, i.e., time delay, complex gain, angle of departure/arrival. We adopt a successive beam training scheme and formulate the training OFDM signal as a third-order low-rank tensor fitting a canonical polyadic (CP) model with factor matrices containing the channel parameters. Exploiting the Vandermonde nature of factor matrices, we propose a structured CP decomposition-based channel estimation strategy aided by the spatial smoothing method, where two dedicated algorithms with particular tensor modeling and parameter recovery operations are developed. The proposed scheme leverages standard linear algebra, and, hence, avoids the random initialization problem and iterative procedure. An analysis of the uniqueness condition of CP decomposition is also pursued. Simulation results indicate that the proposed strategy achieves enhanced estimation performance, which outperforms the traditional approaches in terms of accuracy, robustness and complexity.
45 citations
Cites background from "Millimeter-Wave Cellular Wireless N..."
...2983673 data rates can be delivered by mmWave communications in various environments and applications [3]....
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TL;DR: Numerical results verify the proposed insight that non-line-of-sight transmission caused by obstacles have negligible effects on the proposed system and result is that the ASE can be maximized by optimizing both the targeted data rate and the density of UAVs.
Abstract: In order to satisfy the requirement of high throughput in most UAV applications, the potential of integrating millimeter wave (mmWave) communications with UAV networks is explored in this paper. A tractable three-dimensional (3D) spatial model is proposed for evaluating the average downlink performance of UAV networks at mmWave bands, where the locations of UAVs and users are randomly distributed with the aid of a Poisson cluster process. Moreover, an actual 3D antenna model with the uniform planar array is deployed at all UAVs to examine the impact of both azimuth and elevation angles. Based on this framework and two typical user selection schemes, closed-form approximation equations of the evaluated coverage probability and area spectral efficiency (ASE) are derived. In a noise-limited scenario, an exact expression is provided, which theoretically demonstrates that a large scale of antenna elements is able to enhance the coverage performance. Regarding the altitude of UAVs, there exists at least one optimal height for maximizing the coverage probability. Numerical results verify the proposed insight that non-line-of-sight transmission caused by obstacles have negligible effects on the proposed system. Another interesting result is that the ASE can be maximized by optimizing both the targeted data rate and the density of UAVs.
44 citations
01 Feb 2017
TL;DR: It is proved that a bisection search algorithm is optimal, and that it outperforms exhaustive and iterative search algorithms proposed in the literature and is optimized so as to maximize the overall throughput.
Abstract: Millimeter wave communications rely on narrow-beam transmissions to cope with the strong signal attenuation at these frequencies, thus demanding precise beam alignment between transmitter and receiver. The communication overhead incurred to achieve beam alignment may become a severe impairment in mobile networks. This paper addresses the problem of optimizing beam alignment acquisition, with the goal of maximizing throughput. Specifically, the algorithm jointly determines the portion of time devoted to beam alignment acquisition, as well as, within this portion of time, the optimal beam search parameters, using the framework of Markov decision processes. It is proved that a bisection search algorithm is optimal, and that it outperforms exhaustive and iterative search algorithms proposed in the literature. The duration of the beam alignment phase is optimized so as to maximize the overall throughput. The numerical results show that the throughput, optimized with respect to the duration of the beam alignment phase, achievable under the exhaustive algorithm is 88.3% lower than that achievable under the bisection algorithm. Similarly, the throughput achievable by the iterative search algorithm for a division factor of 4 and 8 is, respectively, 12.8% and 36.4% lower than that achievable by the bisection algorithm.
44 citations
Cites methods from "Millimeter-Wave Cellular Wireless N..."
...…optimized with respect to the duration of the sensing phase, achievable under the bisection algorithm outperforms by 88.3% that achievable by the exhaustive search algorithm, and by 12.8% and 36.4% that achievable under the iterative search algorithm, with division factor of 4 and 8, respectively....
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References
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Book•
15 Jan 1996
TL;DR: WireWireless Communications: Principles and Practice, Second Edition is the definitive modern text for wireless communications technology and system design as discussed by the authors, which covers the fundamental issues impacting all wireless networks and reviews virtually every important new wireless standard and technological development, offering especially comprehensive coverage of the 3G systems and wireless local area networks (WLANs).
Abstract: From the Publisher:
The indispensable guide to wireless communicationsnow fully revised and updated!
Wireless Communications: Principles and Practice, Second Edition is the definitive modern text for wireless communications technology and system design. Building on his classic first edition, Theodore S. Rappaport covers the fundamental issues impacting all wireless networks and reviews virtually every important new wireless standard and technological development, offering especially comprehensive coverage of the 3G systems and wireless local area networks (WLANs) that will transform communications in the coming years. Rappaport illustrates each key concept with practical examples, thoroughly explained and solved step by step.
Coverage includes:
An overview of key wireless technologies: voice, data, cordless, paging, fixed and mobile broadband wireless systems, and beyond
Wireless system design fundamentals: channel assignment, handoffs, trunking efficiency, interference, frequency reuse, capacity planning, large-scale fading, and more
Path loss, small-scale fading, multipath, reflection, diffraction, scattering, shadowing, spatial-temporal channel modeling, and microcell/indoor propagation
Modulation, equalization, diversity, channel coding, and speech coding
New wireless LAN technologies: IEEE 802.11a/b, HIPERLAN, BRAN, and other alternatives
New 3G air interface standards, including W-CDMA, cdma2000, GPRS, UMTS, and EDGE
Bluetooth wearable computers, fixed wireless and Local Multipoint Distribution Service (LMDS), and other advanced technologies
Updated glossary of abbreviations and acronyms, and a thorolist of references
Dozens of new examples and end-of-chapter problems
Whether you're a communications/network professional, manager, researcher, or student, Wireless Communications: Principles and Practice, Second Edition gives you an in-depth understanding of the state of the art in wireless technologytoday's and tomorrow's.
17,102 citations
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...Also, the human body and many outdoor materials being very reflective, allow them to be important scatterers for mmW propagation [28], [30]....
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...However, these measurements were performed in an outdoor campus setting with much lower building density and greater opportunities for LOS connectivity than would be found in a typical urban deployment....
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...Despite the potential of mmW cellular systems, there are a number of key challenges to realizing the vision of cellular networks in these bands: • Range and directional communication: Friis’ transmis- sion law [54] states that the free space omnidirectional path loss grows with the square of the…...
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TL;DR: The motivation for new mm-wave cellular systems, methodology, and hardware for measurements are presented and a variety of measurement results are offered that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.
Abstract: The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm-wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fifth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm-wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.
6,708 citations
"Millimeter-Wave Cellular Wireless N..." refers background or methods in this paper
...In both 28- and 73-GHz measurements, each point was classified as either being in a NLOS or LOS situation, based on a manual classification made at the time of the measurements; see [26] and [28]–[33]....
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...• Empirical NYC: These curves are based on the omnidirectional path loss predicted by our linear model (1) for the mmW channel with the parameters from Table 1, as derived from the directional measurements in [26]....
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...Details of the measurements can be found in [26], [28]– [33], [81]....
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...This tremendous potential has led to considerable recent interest in mmW cellular both in industry [7]–[9], [18], [19] and academia [20]–[26], with a growing belief that mmW bands will play a significant role in beyond 4G and 5G cellular systems [27]....
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...In particular, we survey our own measurements [26], [28]–[33] made in New York City (NYC) in both 28- and 73-GHz bands and the statistical models for the channels developed in [34]....
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TL;DR: The gains in multiuser systems are even more impressive, because such systems offer the possibility to transmit simultaneously to several users and the flexibility to select what users to schedule for reception at any given point in time.
Abstract: Multiple-input multiple-output (MIMO) technology is maturing and is being incorporated into emerging wireless broadband standards like long-term evolution (LTE) [1]. For example, the LTE standard allows for up to eight antenna ports at the base station. Basically, the more antennas the transmitter/receiver is equipped with, and the more degrees of freedom that the propagation channel can provide, the better the performance in terms of data rate or link reliability. More precisely, on a quasi static channel where a code word spans across only one time and frequency coherence interval, the reliability of a point-to-point MIMO link scales according to Prob(link outage) ` SNR-ntnr where nt and nr are the numbers of transmit and receive antennas, respectively, and signal-to-noise ratio is denoted by SNR. On a channel that varies rapidly as a function of time and frequency, and where circumstances permit coding across many channel coherence intervals, the achievable rate scales as min(nt, nr) log(1 + SNR). The gains in multiuser systems are even more impressive, because such systems offer the possibility to transmit simultaneously to several users and the flexibility to select what users to schedule for reception at any given point in time [2].
5,158 citations
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...These multiple antenna systems can be used to form very high gain, electrically steerable arrays, fabricated at the base station (BS), in the skin of a cellphone, or even within a chip [6], [10]–[17]....
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TL;DR: In this article, the authors describe five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter wave, massive MIMO, smarter devices, and native support for machine-to-machine communications.
Abstract: New research directions will lead to fundamental changes in the design of future fifth generation (5G) cellular networks. This article describes five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter wave, massive MIMO, smarter devices, and native support for machine-to-machine communications. The key ideas for each technology are described, along with their potential impact on 5G and the research challenges that remain.
3,711 citations
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
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...Heterogeneous networks, or HetNets, have been one of the most active research areas in cellular standards bodies in the last five years [45], [48], [67], [68], with the main focus being intercell interference coordination and load balancing....
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