Millimeter wave (mm-wave) channel models for outdoor wireless systems with adaptive antennas are needed to exploit the massive bandwidths available at frequencies above 30 GHz. In this paper, we describe 60 GHz wideband propagation measurements in cellular peer-to-peer outdoor environments and in-vehicle scenarios. We present a channel sounder that operates at 38 and 60 GHz with a passband bandwidth of 1.9 GHz. The channel sounder provides sub-ns RMS delay spread measurement resolution and angle-of-arrival (AOA) capabilities. AOA multipath measurements for cellular peer-to-peer communications in an outdoor campus setting show that in all measured locations, some non-Line of Sight (NLOS) antenna orientations can exploit beamforming to create links using scattering in the channel. Measurements using rotating directional antennas in NLOS antenna pointing scenarios found links with up to 36.6 ns RMS delay spread and an average propagation path loss exponent of 4.19, whereas LOS channels provided sub-nanosecond RMS delay spreads and an average path loss exponent of 2.23 (close to free space). Measurements into a vehicle showed similarities to outdoor peer-to-peer environments for LOS channels, but in NLOS situations there was significantly greater path attenuation due to the vehicle interior, vehicle body, windows, and passengers in the vehicle.

http://faculty.poly.edu/~tsr/Publications/l60gz.pdf

Millimeter-Wave 60 GHz Outdoor and Vehicle AOA Propagation Measurements Using a Broadband Channel Sounder

This paper presents a novel ultrawideband wireless spread spectrum millimeter-wave (mmWave) channel sounder that supports both a wideband sliding correlator mode and a realtime spread spectrum mode, also known as wideband correlation or direct correlation. Both channel sounder modes are capable of absolute propagation delay (time of flight) measurements with up to 1 GHz of radio frequency null-to-null bandwidth, and can measure multipath with a 2-ns time resolution. The sliding correlator configuration facilitates long-distance measurements with angular spread and delay spread for up to 185 dB of maximum measurable path loss. The real-time spread spectrum mode is shown to support short-range, small-scale temporal, and Doppler measurements (minimum snapshot sampling interval of 32.753 μs) with a substantial dynamic fading range of 40 dB for human blockage and dynamic urban scenarios. The channel sounder uses field programmable gate arrays, analog-to-digital converters, digital-to-analog converters, and low-phase-noise rubidium standard references for frequency/time synchronization and absolute time delay measurements. Using propagation theory, several methods are presented here to calibrate and verify the accuracy of the channel sounder, and an improved diffraction model for human blockage, based on the METIS model but now including directional antenna gains, is developed from measurements using the channel sounder. The mmWave channel sounder described here may be used for accurate spatial and temporal raytracing calibration, to identify individual multipath components, to measure antenna patterns, for constructing spatial profiles of mmWave channels, and for developing statistical channel impulse response models in time and space.

A Flexible Millimeter-Wave Channel Sounder With Absolute Timing

The paper presents spatio-temporal measurements for the peer-to-peer radio channel at a center frequency of 1920 MHz with 140 MHz of radio-frequency bandwidth. The measurements were taken using a spread-spectrum channel sounder and an automated spatial probing system that uses precise computer-controlled positioning and orientation of omnidirectional and directional (30/spl deg/ beamwidth) antennas to measure both the angles-of-arrival and time-delays of multipath components. We use a unitless definition of angular spread which we proposed previously (see Durgin, G.D. and Rappaport, T.S., IEE Electron. Lett., vol.34, no.25, p.2431-2, 1998). Transmitter-receiver configurations include six outdoor-to-outdoor cross-campus locations at Virginia Polytechnic Institute and State University (17-219 ns rms delay spread, 0.36-0.91 angular spread), three outdoor-to-indoor locations (27-34 ns rms delay spread, 0.78-0.98 angular spread), and three indoor-to-indoor locations (29-45 ns rms delay spread, 0.73-0.90 angular spread). The paper also quantitatively describes a trend that shows how angular spread increases with increasing delay spread.

http://faculty.poly.edu/~tsr/wp-content/uploads/CV/MTJ/2003-05-Wideband%20Measurements%20of%20Angle%20and%20Delay%20Dispersion%20for%20Outdoor%20and%20Indoor%20Peer-to-Peer%20Radio%20Channels%20at%201920%20MHz.pdf

Wideband measurements of angle and delay dispersion for outdoor and indoor peer-to-peer radio channels at 1920 MHz

For radio propagation prediction, recent simulations involving ray tracing offer unprecedented accuracy. These techniques surpass statistical channel models and provide a bounty of additional information including RMS delay spread, angle of arrival, and overall wideband channel impulse response. In particular, three dimensional ray tracing produces an accurate, deterministic channel model for wireless system design. This paper presents a new 3D ray tracing technique of unprecedented speed and accuracy. Simulation results are compared to microcell measurements at 1900 MHz.

http://faculty.poly.edu/~tsr/wp-content/uploads/CV/ICP/1997-05-An%20Advanced%203D%20Ray%20Launching%20Method%20for%20Wireless%20Propagation%20Prediction.pdf

An advanced 3D ray launching method for wireless propagation prediction

Theory of stochastic local area channel modeling for wireless communications

Time dispersion in RF dhannels, induced by multipath caused by reflectors. and scatterers in the propagation environment, must be considered when designing high-rate digital radio systems and wireless modems. This article describes the parameters used to characterize time dispersion and path loss in an RF channel from measured data. Following a discussion of the time dispersion parameters, the analysis and results of measurement data taken in a large train yard in the 902 928 MHz IBM band are presented.

Using RF channel sounding measurements to determine delay spread and path loss

GSM quickly is emerging as the leading cellular radio standard throughout the world. With the advent of new personal communications frequencies irt the 1.8 2 GHz band, GSM and its PCS offshoot, DCS, may be implemented in North America within the next 12 months to 18 months. This tutorial is part of an independent learning program prepared by the authors for the IEEE. This material is taught as part of an introductory course on wireless communications at Virginia Tech and will be included in the textbook Wireless Communications: Principles a.;,d Practice published by Prentice-Hall. Global System for Mobile Communications Global system for mobile communications (GSM) is a second-generation cellular system standard that was developed to solve the fragm~ntation problems of the first cellular systems in Europe [Mou92]. Unlike the U.S. cellular carriers which implemented the firstgeneration analog mobile phone system (AMPS) throughout the country, the first-genera. tion cellular service providers in Europe took a provincial view of cellular. Before GSM, European countries used different cellular standards throughout the continent, and it was not possible for a customer to use a single mobile phone' throughout Europe. After five years and hundreds of person-years of engineering, the European community developed an amazingly·robust and complex cellular standard that was first to specify digital modulation and network level architectures and service. GSM originally was developed to serve just the pan-European cellular market and promised a wide range of network services through the use of integrated services digital network (ISDN). However, during the past two years, GSM's success has exceeded the expectations of virtually everyone, and it is now the world's most popular standard for new cellular radio and personal communications equipment throughout the world. It is predicted that by the year 2000, there will be between 20 million and 50 million GSM subscribers worldwide ·[Mou92], [Dec93]. The task of specifying a common mobile communication system for Europe in the 900 MHz band was taken up by the GSM (Groupe special mobile) committee, which was a working gl-oup of the Conference of Europe6ene Pastes des et Te6le6communication (CEPT). The setting of standards for GSM is currently under the aegis of the European Technical Standards Institute (ETSI). GSM first was introduced into the European market in 1991. By the end of 1993, several non-European countries in South America, Asia and Australia had adopted GSM and the technically equivalent offshoot, DCS 1800, which supports personal communication services (PCS) in the 1.8-2.0 GHz radio bands recently created by governments throughout the world. GSM Services, Features GSM services follow ISDN guidelines and are classified as either teleservices or data services. Teleservices include standard mobile telephony and mobileaoriginated or baseoriginated traffic. Data services include computer-to-computer communication and packet-

Kevin J. Saldanha

Papers

Using RF channel sounding measurements to determine delay spread and path loss

A tutorial on global system for mobile communications (GSM)