Search query: millimeter reflection coefficient urban

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abstract: The spectrum crunch currently experienced by mobile cellular carriers makes the underutilized millimeter wave frequency spectrum a sensible choice for next generation cellular communications, particularly when considering the recent advances in low cost sub terahertz/millimeter wave complementary metal oxide semiconductor circuitry. To date, however, little is known on how to design or deploy practical millimeter wave cellular systems. In this paper, measurements for outdoor cellular channels at 38 GHz were made in an urban environment with a broadband (800 MHz RF passband bandwidth) sliding correlator channel sounder. Extensive angle of arrival, path loss, and multipath time delay spread measurements were conducted for steerable beam antennas of differing gains and beamwidths for a wide variety of transmitter and receiver locations. Coverage outages and the likelihood of outage with steerable antennas were also measured to determine how random receiver locations with differing antenna gains and link budgets could perform in future cellular systems. This paper provides measurements and models that may be used to design future fifth generation millimeter wave cellular networks and gives insight into antenna beam steering algorithms for these systems.
author_names: Theodore Ted S Rappaport

Felix Gutierrez

Eshar Ben-Dor

James Murdock

Yijun Qiao

Jonathan I Tamir
title: Broadband Millimeter Wave Propagation Measurements and Models Using Adaptive Beam Antennas for Outdoor Urban Cellular Communications
venue: IEEE Transactions on Antennas and Propagation
year: 2013

abstract: Measurements on point to point transmission at street level were performed in downtown Denver, CO, with RF probes that operated at 9.6, 28.8, and 57.6 GHz. All probes were mounted on self contained vehicles, permitting a variety of path scenarios. Information on performance of these channels for propagation in an urban environment on both line of sight and non line of sight paths is presented. For non line of sight (non LOS) paths obstructed by buildings of several common materials, results that showed signal attenuations in excess of 100 dB. When the LOS followed a path directly through clear glass walls, the attenuation was small at all probe frequencies. However, when the glass wall had a metalized coating to reduce ultraviolet and infrared radiation, the attenuation increased by 25 to 50 dB for each metallized layer. In most cases no signals could be detected through steel reinforced concrete or brick buildings.
author_names: Edmond J Violette

Richard H Espeland

Robert O DeBolt

Felix K Schwering
title: Millimeter wave propagation at street level in an urban environment
year: 1988

abstract: Almost all mobile communication systems today use spectrum in the range of 300 MHz 3 GHz. In this article, we reason why the wireless community should start looking at the 3 300 GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages for mobile communication. We introduce a millimeter wave mobile broadband (MMB) system as a candidate next generation mobile communication system. We demonstrate the feasibility for MMB to achieve gigabit per second data rates at a distance up to 1 km in an urban mobile environment. A few key concepts in MMB network architecture such as the MMB base station grid, MMB interBS backhaul link, and a hybrid MMB 4G system are described. We also discuss beamforming techniques and the frame structure of the MMB air interface.
author_names: Zhouyue Pi

Farooq Khan
title: An introduction to millimeter wave mobile broadband systems
venue: IEEE Communications Magazine
year: 2011

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.
author_names: Sundeep Rangan

Theodore Ted S Rappaport

Elza Erkip
title: Millimeter Wave Cellular Wireless Networks: Potentials and Challenges
venue: Proceedings of the IEEE
year: 2014

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.
author_names: Mustafa Riza Akdeniz

Yuanpeng Liu

Shu Sun

Sundeep Rangan

Theodore Ted S Rappaport

Elza Erkip
title: Millimeter Wave Channel Modeling and Cellular Capacity Evaluation
venue: IEEE Journal on Selected Areas in Communications
year: 2014

abstract: Since millimeter wave (mm wave) communications systems deployed in urban environments will be an important component of next generation cellular communications, it is important to understand the propagation channels those systems will be working in. This paper provides an overview of the state of the art in urban mm wave channel modeling, and outlines directions for future research. Propagation at mm wave differs in several critical aspects from those at microwave frequencies: much higher free space pathloss, a smaller number of multipath components, the inefficiency of diffraction as a propagation process, the importance of body shadowing, and possibly more diffuse scattering all impacts the channel characteristics. The paper will also review the new challenges for channel sounding in this frequency band, in particular for the pathloss, and finally review stochastic and semi deterministic modeling approaches suitable for these channels. It is clear that while some important work has been done, a lot of topics remain open for future work.
author_names: Andreas F Molisch

Aki Karttunen

Rui Wang

Celalettin Umit Bas

Sooyoung Hur

Jeongho Park

Jianzhong Zhang
title: Millimeter wave channels in urban environments
venue: 2016 10th European Conference on Antennas and Propagation (EuCAP)
year: 2016

abstract: Millimeter wave imaging techniques and systems have been developed at the Pacific Northwest National Laboratory (PNNL) Richland, WA, for the detection of concealed weapons and contraband at airports and other secure locations. These techniques were derived from microwave holography techniques that utilize phase and amplitude information recorded over a two dimensional aperture to reconstruct a focused image of the target. Millimeter wave imaging is well suited for the detection of concealed weapons or other contraband carried on personnel since millimeter waves are nonionizing, readily penetrate common clothing material, and are reflected from the human body and any concealed items. In this paper, a wide bandwidth three dimensional holographic microwave imaging technique is described. Practical weapon detection systems for airport or other high throughput applications require high speed scanning on the order of 3 to 10 s. To achieve this goal, a prototype imaging system utilizing a 27 33 GHz linear sequentially switched array and a high speed linear scanner has been developed and tested. This system is described in detail along with numerous imaging results.
author_names: David M Sheen

Douglas L McMakin

Thomas E Hall
title: Three dimensional millimeter wave imaging for concealed weapon detection
year: 2001

abstract: Recently, there has been considerable interest in new tiered network cellular architectures, which would likely use many more cell sites than found today. Two major challenges will be i) providing backhaul to all of these cells and ii) finding efficient techniques to leverage higher frequency bands for mobile access and backhaul. This paper proposes the use of outdoor millimeter wave communications for backhaul networking between cells and mobile access within a cell. To overcome the outdoor impairments found in millimeter wave propagation, this paper studies beamforming using large arrays. However, such systems will require narrow beams, increasing sensitivity to movement caused by pole sway and other environmental concerns. To overcome this, we propose an efficient beam alignment technique using adaptive subspace sampling and hierarchical beam codebooks. A wind sway analysis is presented to establish a notion of beam coherence time. This highlights a previously unexplored tradeoff between array size and wind induced movement. Generally, it is not possible to use larger arrays without risking a corresponding performance loss from wind induced beam misalignment. The performance of the proposed alignment technique is analyzed and compared with other search and alignment methods. The results show significant performance improvement with reduced search time.
author_names: Sooyoung Hur

Taejoon Kim

David James Love

James V Krogmeier

Timothy A Thomas

Amitava Ghosh
title: Millimeter Wave Beamforming for Wireless Backhaul and Access in Small Cell Networks
venue: IEEE Transactions on Communications
year: 2013

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.
author_names: Theodore Ted S Rappaport

Shu Sun

Rimma Mayzus

Hang Zhao

Yaniv Azar

Kevin Wang

George N Wong

Jocelyn K Schulz

Mathew Samimi

Felix Gutierrez
title: Millimeter Wave Mobile Communications for 5G Cellular: It Will Work!
venue: IEEE Access
year: 2013

abstract: Millimeter wave (mmWave) holds promise as a carrier frequency for fifth generation cellular networks. Because mmWave signals are sensitive to blockage, prior models for cellular networks operated in the ultra high frequency (UHF) band do not apply to analyze mmWave cellular networks directly. Leveraging concepts from stochastic geometry, this paper proposes a general framework to evaluate the coverage and rate performance in mmWave cellular networks. Using a distance dependent line of site (LOS) probability function, the locations of the LOS and non LOS base stations are modeled as two independent non homogeneous Poisson point processes, to which different path loss laws are applied. Based on the proposed framework, expressions for the signal to noise and interference ratio (SINR) and rate coverage probability are derived. The mmWave coverage and rate performance are examined as a function of the antenna geometry and base station density. The case of dense networks is further analyzed by applying a simplified system model, in which the LOS region of a user is approximated as a fixed LOS ball. The results show that dense mmWave networks can achieve comparable coverage and much higher data rates than conventional UHF cellular systems, despite the presence of blockages. The results suggest that the cell size to achieve the optimal SINR scales with the average size of the area that is LOS to a user.
author_names: Tianyang Bai

Robert W Heath
title: Coverage and Rate Analysis for Millimeter Wave Cellular Networks
venue: IEEE Transactions on Wireless Communications
year: 2015