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: The joint user association and resource allocation problem in a multi-band mmWave HetNet where different bands have different propagation characteristics is investigated and a near-optimal solution based on the Markov approximation framework is developed.
Abstract: Millimeter-wave (mmWave) heterogeneous network (HetNet) has been regarded as a promising means to improve the cellular system capacity in the 5G era. In this paper, we investigate the joint user association and resource allocation problem in a multi-band mmWave HetNet where different bands have different propagation characteristics. According to whether a user can transmit on multiple mmWave bands simultaneously, two different access schemes are considered: the single-band access scheme and the multi-band access scheme. For the single-band access scheme, we first find a closed-form expression for the optimal time fraction allocation and then develop an iterative algorithm for joint user association and power allocation based on the Lagrangian dual decomposition methods and the Newton-Raphson method. For the multi-band access scheme, we develop a near-optimal solution based on the Markov approximation framework. Our analytical results reveal that different users can only access at most one band simultaneously although the multi-band access scheme allows a user to transmit on multiple bands. Finally, numerical results demonstrate that the multi-band access scheme performs better than the single-band access scheme, especially in the light load scenario.
33 citations
Cites background from "Millimeter-Wave Cellular Wireless N..."
...[13] have discussed several key challenges of the realization of mmWave cellular networks, including initial access, channel structure, and media access control (MAC) layer design....
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Posted Content•
TL;DR: In this article, a stochastic geometry approach to the connectivity of mmWave networks with multi-hop relaying is presented, where the random positions and shapes of obstacles in the radio environment are modeled as a Boolean model, whose germs are distributed according to a Poisson point process.
Abstract: This paper presents a novel stochastic geometry approach to the connectivity of milimeter wave (mmWave) networks with multi-hop relaying. The random positions and shapes of obstacles in the radio environment are modeled as a Boolean model, whose germs are distributed according to a Poisson point process and grains are random rectangles. The derived analytical results shed light on how the connectivity of mmWave networks depends on key system parameters such as the density and size of obstacles as well as relaying route window -- the range of distances in which routing relays are selected. We find that multi-hop relaying can greatly improve the connectivity versus single hop mmWave transmission. We show that to obtain near-optimal connectivity the relaying route window should be about the size of the obstacles.
33 citations
TL;DR: This work quantifies the number of mmWave service antennas that are needed to duplicate the performance of a specified number of PCS (1.9 GHz) service antennas and considers a modest PCS deployment of 128 antennas serving 18 terminals.
Abstract: If we assume line-of-sight propagation and perfect channel state information at the base station -- consistent with slow moving terminals -- then a direct performance comparison between Massive MIMO at PCS and mmWave frequency bands is straightforward and highly illuminating. Line-of-sight propagation is considered favorable for mmWave because of minimal attenuation and its facilitation of hybrid beamforming to reduce the required number of active transceivers. We quantify the number of mmWave (60 GHz) service antennas that are needed to duplicate the performance of a specified number of PCS (1.9 GHz) service antennas. As a baseline we consider a modest PCS deployment of 128 antennas serving 18 terminals. At one extreme, we find that, to achieve the same per-terminal maxmin 95 percent-likely downlink throughput in a single-cell system, 20,000 mmWave antennas are needed. To match the total antenna area of the PCS array would require 128,000 half-wavelength mmWave antennas, but a much reduced number is adequate because the large number of antennas also confers greater channel orthogonality. At the other extreme, in a highly interference-limited multi-cell environment, only 215 mmWave antennas are needed; in this case, increasing the transmitted power yields little improvement in service quality.
33 citations
TL;DR: In this article, a differential feeding circularly polarized antenna array implemented with printed ridge gap waveguide technology for millimeter-wave applications is proposed, which achieves a stable 180° phase imbalance over 20% operating bandwidth at 30 GHz with sufficient matching level.
Abstract: In this paper, a differential feeding circularly polarized antenna array implemented with printed ridge gap waveguide technology for millimeter-wave applications is proposed. The differential feeding power divider is designed based on aperture coupling to achieve a stable 180° phase imbalance over 20% operating bandwidth at 30 GHz with sufficient matching level. This power divider is deployed to excite and test the proposed differential feeding antenna. The proposed antenna is formed by a rectangular aperture having a circular-shaped polarizer consisting of patch surrounded by an open-end ring, which is differentially fed. This polarizer is deployed to achieve a circular polarization radiation through a 10 % frequency bandwidth. A high-gain antenna array is implemented by extending the aperture size to have four radiating elements. The antenna array is fabricated, where the experimental results verify a −10 dB impedance bandwidth from 27.7 to 32.4 GHz (15.6%). Moreover, a 3 dB axial ratio bandwidth over 10 % is achieved, which is sufficient enough to cover the operating bandwidth of potential 5G applications at 30 GHz. The fabricated prototype achieves a 3 dB gain of 14 dB, with low cross polarization and a radiation efficiency higher than 84% over the whole operating frequency bandwidth.
33 citations
19 Mar 2017
TL;DR: The scheme proposed in this paper can significantly enhance network throughput by exploiting space-division multiple access, i.e., allowing non-conflicting flows to be transmitted simultaneously and achieves significant gain over benchmark schemes in terms of user throughput.
Abstract: Millimeter wave (mm-wave) frequencies provide orders of magnitude larger spectrum than current cellular allocations and allow usage of high dimensional antenna arrays for exploiting beamforming and spatial multiplexing. This paper addresses the problem of joint scheduling and radio resource allocation optimization in mm-wave heterogeneous networks where mm-wave small cells are densely deployed underlying the conventional homogeneous macro cells. Furthermore, mm-wave small cells operate in time division duplexing mode and share the same spectrum and air-interface for backhaul and access links. The scheme proposed in this paper can significantly enhance network throughput by exploiting space-division multiple access, i.e., allowing non-conflicting flows to be transmitted simultaneously. The optimization problem of maximizing network throughput is formulated as a mixed integer nonlinear programming problem. To find a practical solution, this is decomposed into three steps: concurrent transmission scheduling, time resource allocation, and power allocation. A maximum independent set based algorithm is developed for concurrent transmission scheduling to improve resource utilization efficiency with low computational complexity. Through extensive simulations, we demonstrate that the proposed algorithm achieves significant gain over benchmark schemes in terms of user throughput.
33 citations
Cites background from "Millimeter-Wave Cellular Wireless N..."
..., directional transmissions with proper beamforming, while mm-wave signals can be severely vulnerable to shadowing, resulting in outages and intermittent channel quality [4]....
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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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