Andrzej Partyka

Investigation of Prediction Accuracy, Sensitivity, and Parameter Stability of Large-Scale Propagation Path Loss Models for 5G Wireless Communications

This paper compares three candidate large-scale propagation path loss models for use over the entire microwave and millimeter-wave (mmWave) radio spectrum: the alpha-beta-gamma (ABG) model, the close-in (CI) free-space reference distance model, and the CI model with a frequency-weighted path loss exponent (CIF). Each of these models has been recently studied for use in standards bodies such as 3rd Generation Partnership Project (3GPP) and for use in the design of fifth-generation wireless systems in urban macrocell, urban microcell, and indoor office and shopping mall scenarios. Here, we compare the accuracy and sensitivity of these models using measured data from 30 propagation measurement data sets from 2 to 73 GHz over distances ranging from 4 to 1238 m. A series of sensitivity analyses of the three models shows that the four-parameter ABG model underpredicts path loss when relatively close to the transmitter, and overpredicts path loss far from the transmitter, and that the physically based two-parameter CI model and three-parameter CIF model offer computational simplicity, have very similar goodness of fit (i.e., the shadow fading standard deviation), exhibit more stable model parameter behavior across frequencies and distances, and yield smaller prediction error in sensitivity tests across distances and frequencies, when compared to the four-parameter ABG model. Results show the CI model with a 1-m reference distance is suitable for outdoor environments, while the CIF model is more appropriate for indoor modeling. The CI and CIF models are easily implemented in existing 3GPP models by making a very subtle modification - by replacing a floating non-physically based constant with a frequency-dependent constant that represents free-space path loss in the first meter of propagation. This paper shows this subtle change does not change the mathematical form of existing ITU/3GPP models and offers much easier analysis, intuitive appeal, better model parameter stability, and better accuracy in sensitivity tests over a vast range of microwave and mmWave frequencies, scenarios, and distances, while using a simpler model with fewer parameters.

Propagation Path Loss Models for 5G Urban Micro- and Macro-Cellular Scenarios

This paper presents and compares two candidate large-scale propagation path loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space reference distance model, for the design of fifth generation (5G) wireless communication systems in urban micro- and macro-cellular scenarios. Comparisons are made using the data obtained from 20 propagation measurement campaigns or ray- tracing studies from 2 GHz to 73.5 GHz over distances ranging from 5 m to 1429 m. The results show that the one-parameter CI model has a very similar goodness of fit (i.e., the shadow fading standard deviation) in both line-of-sight and non-line-of-sight environments, while offering substantial simplicity and more stable behavior across frequencies and distances, as compared to the three-parameter ABG model. Additionally, the CI model needs only one very subtle and simple modification to the existing 3GPP floating-intercept path loss model (replacing a constant with a close-in free space reference value) in order to provide greater simulation accuracy, more simplicity, better repeatability across experiments, and higher stability across a vast range of frequencies.

Indoor mm-Wave Channel Measurements: Comparative Study of 2.9 GHz and 29 GHz

The millimeter-wave (mm-Wave) frequency band ~30-300 GHz has received significant attention lately as a prospective band for 5G systems. Millimeter-wave frequencies have traditionally been used for backhaul, satellite and other fixed services. While these bands offer substantial amount of bandwidth and opportunity for spatial multiplexing, the propagation characteristics for terrestrial mobile usage need to be fully understood prior to system design. Towards this end, this paper presents preliminary indoor measurement results obtained using a channel sounder equipped with omni- and directional antennas at 2.9 GHz and 29 GHz as a comparative study of the two bands. The measurements are made within a Qualcomm building in Bridgewater, NJ, USA, for two separate floors, each representing a different yet representative type of office plan. We present measurements and estimated parameters for path loss, excess delay, RMS delay and analyze the power profile of received paths. In addition, we present several spherical scans of particular links to illustrate the 3-D angular spread of the received paths. This work represents initial results of an ongoing effort for comprehensive indoor and outdoor channel measurements. The measurements presented here, along with cited references, offer interesting insights into propagation conditions (e.g. loss, delay/angular spread etc.), coverage and robustness for mobile use of millimeter-wave bands. We believe additional extensive measurement campaigns in diverse settings by academia and industry would help facilitate the generation of usable channel models.

Millimeter Wave Channel Measurements and Implications for PHY Layer Design

There has been an increasing interest in the millimeter wave (mmW) frequency regime in the design of the next-generation wireless systems. The focus of this paper is on understanding mmW channel properties that have an important bearing on the feasibility of mmW systems in practice and have a significant impact on physical layer design. In this direction, simultaneous channel sounding measurements at 2.9, 29, and 61 GHz are performed at a number of transmit–receive location pairs in indoor office, shopping mall, and outdoor environments. Based on these measurements, this paper first studies large-scale properties, such as path loss and delay spread across different carrier frequencies in these scenarios. Toward the goal of understanding the feasibility of outdoor-to-indoor coverage, material measurements corresponding to mmW reflection and penetration are studied and significant notches in signal reception spread over a few gigahertz are reported. Finally, implications of these measurements on system design are discussed, and multiple solutions are proposed to overcome these impairments.

Coverage and capacity of 28 GHz band in indoor stadiums

High user density in stadiums and auditoriums is a challenging scenario for deploying future generation wireless networks. Due to the almost line-of-sight propagation model, the LTE base stations and WiFi access points would interfere with each other and result in reduced throughput in this scenario. Millimeter and microwave bands can play an important role in this regard due to their spatial reuse capability. This paper focuses on the coverage and capacity of the 28 GHz band in indoor stadiums and auditoriums. We model an indoor basketball stadium and human blockage loss. We consider two different types of human blockage models: (i) knife edge diffraction model and (ii) experimental blockage model. We develop the experimental blockage model while making measurements in a small-scale stadium-like seating area. Our experiments suggest that the boresight direction is irrelevant in the presence of multiple surrounding scattering objects. Scattering and reflections of signals from neighboring human bodies can provide strong signal paths at the millimeter wave band in indoor stadiums. Based on this model, we simulate the connectivity of the 28 GHz band with different sitting and standing patterns among audience. Simulation results suggest that ten base stations can sustain a sum rate of 76 Gbps and 227 Gbps with one and four RF chains respectively in 50 percentile case. We also show that the 28 GHzs sustainable data rate can be 11 and 33 times higher than the 5 GHzs sustainable data rate with one and four RF chains respectively.

Study of the Indoor Millimeter Wavelength Channel

In this paper, we conduct ray-tracing simulation studies using WinProp tool to understand the path loss, coverage area, diversity and delay spread of the 29GHz band in the indoor propagation environment, and compare the 29GHz indoor channel to the 2.9GHz indoor channel. In addition, we compare our simulation results with the measurement data from [4]. Based on our simulation results, we conclude that the 29GHz band has similar indoor channel characteristics as 2.9GHz and that any inherent impairment of the mmWave due to higher carrier frequency can easily compensated with beam forming techniques and other advanced algorithms. Specifically, our results show that the path loss exponents and the RMS delay spread values are similar at 29GHz and at 2.9GHz. In addition, our simulation results show that by having multiple access points on an office floor, we can significantly improve important diversity metrics such as the number of detectable beams and the angular separation of those beams, so as to make 29GHz system using beam forming technique more robust against beam blockage.