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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19 May 2008
TL;DR: It is shown that huge gains in coverage and capacity are obtained by relaying, without the need of a cable or fiber access, on the island of Jersey.
Abstract: Broadband wireless access will be deployed in a cellular way with 3GPP-LTE [1]. For the first rollout the main demand is a huge area coverage. With only few available base station sites that are connected to an access fiber, multihop (relaying) techniques can be used well to fill the coverage gaps. Later with increasing offered traffic, the demand shifts to higher capacity over the area. Even for this purpose relays are beneficial. There is an area around relays where they provide better overall capacity to the user terminal, taking into account all resources used for the first and second hop (the relaying overhead). Relaying or Multihop operation therefore massively improves the coverage as well as the capacity goals at low cost, without the need of a cable or fiber access. This paper analyzes a realistic urban scenario on the island of Jersey. We study the coverage and capacity over the area in three cases. One base station (BS) only, one BS with four relay nodes (RNs), and the latter plus another ring of nine RNs. The BS has fiber access for rates beyond 100 Mbit/s, while the first hop of Relays (HI) is fed over the air from BS using shared resources in the same LTE band. The second hop H2 is fed by the relays of group HI. In this paper we provide the results from numeric analysis based on models we explain here. It is shown that huge gains in coverage and capacity are obtained by relaying.
68 citations
TL;DR: The proposed adaptive power/ground architecture eliminates the headroom limitations due to the deeply scaled power supply in nanometer CMOS technologies, while preserving the intrinsic speed of thin-oxide MOSFETs with minimum channel length for key analog blocks.
Abstract: A 12-bit 3 GS/s 40 nm two-way time-interleaved pipeline analog-to-digital converter (ADC) is presented. The proposed adaptive power/ground architecture eliminates the headroom limitations due to the deeply scaled power supply in nanometer CMOS technologies, while preserving the intrinsic speed of thin-oxide MOSFETs with minimum channel length for key analog blocks. Moreover, in terms of the signal swing, the proposed reference extrapolation scheme offers a smooth transition between the multiplying digital-to-analog converter stages and the last flash stage. With these two techniques, the ADC achieves a SNR of 61 dB and a DNL of -0.5/+0.5 LSB, while consuming 500 mW at a 3 GS/s sampling rate and occupying an area of 0.4 mm2 in 40 nm CMOS process.
64 citations
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...For example, scaling power consumption levels of even a state-of-the-art CMOS A/D converter designs such as [63] and [64] suggests that A/D converters at rates of 100 Ms/s at 12 b and 16 antennas would require more than 250 mW, a significant drain for current mobile devices....
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TL;DR: The recently ratified IEEE 802.11n standard is today's fastest Wi-Fi technology, but users want even faster versions for applications such as wireless video.
Abstract: The recently ratified IEEE 802.11n standard is today's fastest Wi-Fi technology. But users want even faster versions for applications such as wireless video.
64 citations
10 Jun 2014
TL;DR: In this article, the authors present millimeter wave propagation measurements in New York City and an analysis of signal outage at 28 and 73 GHz using similar spread spectrum sliding correlator channel sounders that employed high gain, directional steerable antennas at both the transmitter and receiver.
Abstract: This paper presents millimeter wave propagation measurements in New York City and an analysis of signal outage at 28 and 73 GHz using similar spread spectrum sliding correlator channel sounders that employed high gain, directional steerable antennas (24.5 dBi gain antennas at 28 GHz and 27 dBi gain antennas at 73 GHz) at both the transmitter and receiver. Three identical transmitter locations were used for both the 28 and 73 GHz campaigns, while the 73 GHz campaign included two new TX locations. The 28 GHz campaign tested 25 receiver locations for each of the three transmitter locations, and the 73 GHz campaign tested 27 receiver locations in various combinations with the five transmitter sites. Overall, 75 TX-RX location combinations were tested at 28 GHz and 74 TX-RX combinations were tested at 73 GHz, with T-R (transmitter-receiver) separation distances up to 425 m. The maximum transmit power was 30 dBm at 28 GHz and 14.6 dBm at 73 GHz. Our analysis shows that the estimated outage probabilities at 28 and 73 GHz for the cellular communication scenario are 14% and 17%, respectively, and is 16% for the 73 GHz backhaul scenario.
61 citations
13 Mar 2005
TL;DR: The results show that a time-division relay strategy can far outperform a receive-and-retransmit relay strategy and for a wide range of system parameters, optimally placed relay nodes can significantly increase the network expected throughput capacity.
Abstract: Wireless relay nodes can improve the capacity of wireless networks. In this work, we integrate wireless relay nodes into the infrastructure of a wireless local area network (WLAN). In particular, we investigate the effect of different relay strategies and optimal utilization of a fixed number of immobile relay nodes, which maximizes the expected throughput capacity of the network. We study how the number of relay nodes, the range of users, transmission power, path loss exponent, and traffic characteristics affect the optimal relay node placement and expected throughput capacity of the network. Our results show that a time-division relay strategy can far outperform a receive-and-retransmit relay strategy. Furthermore, for a wide range of system parameters, optimally placed relay nodes can significantly increase the network expected throughput capacity.
59 citations
"Millimeter-Wave Cellular Wireless N..." refers background in this paper
...In current cellular systems, relaying has been primarily used both for coverage extension and, to a lesser extent, capacity expansion when backhaul is not available [99]–[101]....
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