doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 1 Project: IEEE Study Group for Wireless Personal Area Networks (WPANs) Submission Title: [An Ultra-Wideband Channel Model and Coverage for Farm/Open-Area Applications] Date Submitted: [12 July, 2004] Source: [Shahriar Emami, Celestino A. Corral, Gregg Rasor]: Company1 [Freescale Semiconductor], Address [8000 W. Sunrise Blvd., Plantation, FL 33322], Voice:[(954) ], FAX: [(954) ], Re: [Channel Model Submission] Abstract:[An ultra-wideband channel model for open area/farm applications is submitted. The channel model is based on ray tracing that captures signal descriptors including frequencies. The rationale behind the channel model is developed and presented in support of the presentation.] Purpose:[An understanding of the open area outdoor environment for ultra-wideband (UWB) signal coverage is needed for TG4a. This channel model should assist in predicting UWB range and proper signal design for open area applications.] Notice:This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 2 An Ultra-Wideband Channel Model and Coverage for Farm/Open-Area Applications Shahriar Emami, Celestino A. Corral and Gregg Rasor Freescale Semiconductor

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 3 Outline Preliminaries -Prior Art -Simulated Environment -Approach -Simulation Setup Proposed Channel Models -2 Ray and 3 Ray Models -Amplitude Statistics -Model Parameters -Ray Locations Simulation Results - Terrain Variations - Ground Conditions - Polarization Diversity - Additional Scatterers Summary and Conclusions

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 4 Prior Art Prior Efforts : –Two-ray UWB path loss model: S. Sato and T. Kobayashi, “Path-loss exponents of ultra wideband signals in line-of-sight environments,” IEEE a, March –Hybrid deterministic/statistical narrowband approach for roadways: A. Domazetovic, L.J. Greenstein, N.B. Mandayam, I. Seskar, “A new modeling approach for wireless channels with predictable path geometries,” VTC 2002-Fall Proceedings, Volume 1, pp , Sept –Deterministic UWB channel model based on ray tracing approach: B. Uguen, E. Plouhinec, Y. Lostanlen, and G. Chassay, “A deterministic ultra wideband channel modeling,” 2002 IEEE Conf. Ultra Wideband Syst. Tech. We use approach considered here

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 5 Simulated Environment Farm areas feature isolated clusters of scatterers Scatterers include wooden house, silo and up to three tractors Ground is not flat Impact of dry/wet conditions

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 6 Approach Use narrowband deterministic 3-D ray tracing simulator - Employs –Geometric Optics (GO) –Uniform Theory of Diffraction (UTD) –Generates Received signal strength Ray statistics (path length/delay) Signal descriptors include frequency, polarization, etc. UWB channel sounding is achieved by superposition of NB channel sounding - FCC emissions mask scaled channel sounding (constrained channel sounding)

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 7 Approach- Cnt’d Energy of band concentrated in high band frequency Constrained Channel Sounding

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 8 Simulation Set-Up 3-D omni antenna pattern used Omni pattern assumed at all frequencies Farm area consists of two-story wood home and metal grain silo. Ground is not flat; has slight variations in height. omni antenna above house omni antenna near ground Receiver grid placed around home, 200m X 200m Receiver spacing was 4m X 4m Receiver height was at 1.3m For omni antenna above house, antenna was at 12.5m height For omni antenna near ground, antenna was at 1.5m height.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 9 Coverage Results Highest level dBm Wet soil

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 10 Towards a Channel Model These are only a small number of rays in each CIR Majority of energy is contained in 2 or 3 rays. 2 Ray Model. 3 Ray Model

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 11 2 Ray Model 3 Ray Model Block Diagram Representation

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 12 Simulation Results—Ray Statistics Statistics of the two rays are found to be Rayleigh distributed.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 13 Comparison Figure of Merit: Percentage of locations that a model captures 90% or more of their PDP power. 2 ray model and 3 ray models work well for about 76% and 91% of locations. 3 ray model is superior to 2 ray model.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 14 Channel Model Parameters Phase angles have uniform distributions over [0  ]. Amplitude statistics are provided in the table. MED, RMS delay spread and channel length are used to compute the ray locations. CM1 (5 m)CM2 (15 m)CM3 (75 m) Ray 1 (m,  (1.8e-5, 1.5e-10)(8e-6, 1.36e-11)(4.8e-6,1.49e-12) Ray 2 (m,  (1.6e-6, 2.35e-14)(2.2e-6, 1.3e-12)(6.7e-7, 9.16e-15) Ray 3 (m,  (3.2e-6, 1.32e-12)(1.06e-6,1.82e-13)(5.38e-7,2.68e-15) MED (ns) RMS Delay (ns) d (ns)

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 15 Ray Locations (2 Ray Model) Two ray model is Second moment of power delay profile can be computed using mean excess delay and rms delay spread Two Rayleigh random variables with mean and variance corresponding to mean and variance of the two rays are generated. Two uniformly distributed random phases over [0, 2  ] are generated as well. We have and.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 16 Ray Locations (2 Ray Model) - Cont’d Ray locations are found by solving the system of equation: and where and.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 17 Ray Locations (3 Ray Model) Three ray model is Second moment of power delay profile can be computed using mean excess delay and rms delay spread and. Three Rayleigh random variables with mean and variance corresponding to mean and variance of the two rays are generated. Three uniformly distributed random phases over [0, 2  ] are generated as well. We have and.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 18 Ray Locations (3 Ray Model) - Cont’d The first ray locations are found by solving the following equation: where,, and. Second and third rays are given by and.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 19 Terrain variations High correlation Low correlation Environment A Height = 0.1 m & high correlation Environment BHeight = 0.1 m & low correlation Environment C Height = 0.3 m & high correlation Environment DHeight = 0.3 m & low correlation Environment E Height = 0.5 m & high correlation Environment FHeight = 0.5 m & low correlation

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 20 Terrain variations- Cont’d Environment2 ray model3 ray model A B C D E F

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 21 Received Power, Mean Excess Delay (MED) and RMS Delay Spread Estimated over a number of environments ABCDEF Rx. Power (dBm) MED (ns) RMS Delay (ns)

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 22 Simulation Results—Ground Conditions Ground conditions (wet or dry) has very little impact on received signal power or delay spread.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 23 Polarization Diversity Polarization diversity is not beneficial.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 24 Additional Scatterers Tractor Typical simulation result for 1 tractor

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 25 Additional Scatterers Consider a few scenarios where additional scatterers are tossed in the farm environment Determine the figure of merit for each 2 ray mode3 ray model Scenario Scenario Scenario Considerable amount of scattering occurs in some regions in Scenario 3. Even three ray model is insufficient.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 26 Summary and Conclusions UWB Ray Tracing: UWB channel sounding is accomplished with the aid of narrow band ray tracing. Ray tracer utilizes realistic antennas and appropriate material properties. CIR of UWB channel is found by superposition of CIR of individual narrow bands responses. Channel Modeling Results: Two ray and three ray channel models were proposed. Procedures for generating channel models were discussed. Percentage of locations capturing 90% of PDP energy was selected as the figure of merit. Three ray channel model is superior to two ray model. Both models were found to be insensitive to terrain variations. Simulation Results. RF parameters appear almost insensitive to ground conditions. Ground conditions (wet or dry) have little impact on coverage and delay spread. Transmit polarization diversity not helpful in farm environment.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 27 Back-up Slides

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 28 Material Properties Pellat-Debye Equations for loss at single relaxation time. Real permittivity exhibits low- pass frequency response. Imaginary part exhibits band- pass response. Regions can be separated for different relaxation times. Temperature effects are not modeled, but only affected by change in density of dielectric material. Reference Data for Engineers: Radio, Electronics, Computer & Communications, 8 th Ed., Carmel, Indiana: SAMS, Prentice-Hall Computer Pub., 1993.

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 29 Simulation Results—Channel Sounding Channel (uniform) sounding leads to larger received power as compared to constrained channel (FCC-mask compliant) sounding. Over 10dB difference FCC-mask complaint Uniform sounding

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 30 Simulation Results— “High-pass” or “Band-pass” Sounding “Band-pass” sounding results in +1 dB higher received power compared to “high- pass” sounding. High-pass Band-pass

doc.: IEEE a Contribution July 12, 2004 Shahriar Emami, Freescale SemiconductorSlide 31 Simulation Results— Channel Impulse Response CIR is similar to two-ray model.