Modeling Environmental Effects on Directionality in Wireless - PowerPoint PPT Presentation

Modeling Environmental Effects on Directionality in Wireless Networks Eric Anderson, Caleb Phillips, Douglas Sicker, and Dirk Grunwald eric.anderson@colorado.edu University of Colorado Department of Computer Science 26 June 2009 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 1 / 22

Outline Radio Propagation Environments and Directional Antennas 1 Pretty Pictures Measuring Effective Directionality Accuracy of Current Models Estimating Radio Propagation 2 Ray Tracing Propagation Models Directivity Models Directivity and Propagation are not Orthogonal 3 What’s Missing? Modeling 4 Fitting Specific Environments Fitting Types of Environments Relating Signals to Environment Parameters � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 2 / 22

RF Propagation Environments � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 3 / 22

RF Propagation Environments � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 3 / 22

Measurement Processes [1/2] Baseline Measurements Calibration and test quality equipment (Agilent E4438C, 89600S VSG and VSA) used for: Reference pattern Calibrating laptop measurements. � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 4 / 22

Measurement Processes [2/2] Linear fit for RSS Error −20 Laptop Measurements −40 Dell laptops Rx dBm Atheros AR5213 −60 radios Used for −80 non-reference measurements. −80 −60 −40 −20 Tx dBm Linear fit, slope ≈ 0 . 95 Adjusted R 2 = 0 . 989 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 5 / 22

How Bad is it? Patch−Panel Antenna 10 0 dB Relative to Peak Mean −10 −20 −30 −40 Patch−Outdoor−B Patch−Outdoor−A Patch−Indoor−A −50 Reference 0 25 50 75 105 140 175 210 245 280 315 350 Angle, Degrees Counterclockwise � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 6 / 22

How Bad is it? Patch−Panel Antenna 10 0 dB Relative to Peak Mean −10 −20 ≥ 15 dB −30 −40 Patch−Outdoor−B Patch−Outdoor−A Patch−Indoor−A −50 Reference 0 25 50 75 105 140 175 210 245 280 315 350 Angle, Degrees Counterclockwise � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 6 / 22

How Bad Is It? 24dBi Parabolic Dish, Indoors 10 0 dB Relative to Peak Mean −10 −20 ≥ 35 dB −30 −40 Parabolic−Indoor−C Parabolic−Indoor−B Parabolic−Indoor−A −50 Reference 0 21 50 76 106 140 171 205 236 270 301 335 Angle, Degrees Counterclockwise � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 7 / 22

Outline Radio Propagation Environments and Directional Antennas 1 Pretty Pictures Measuring Effective Directionality Accuracy of Current Models Estimating Radio Propagation 2 Ray Tracing Propagation Models Directivity Models Directivity and Propagation are not Orthogonal 3 What’s Missing? Modeling 4 Fitting Specific Environments Fitting Types of Environments Relating Signals to Environment Parameters � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 8 / 22

Radio Ray Tracing � �� �� f a ( θ 1 ) f b ( θ 2 ) d − 2 P rx = P tx � 1 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 9 / 22

Radio Ray Tracing � �� �� f a ( θ 1 ) f b ( θ 2 ) d − 2 + f a ( θ 3 ) f b ( θ 4 ) d − 2 P rx = P tx 2 A 2 “two-ray” � 1 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 9 / 22

Radio Ray Tracing � �� �� f a ( θ 1 ) f b ( θ 2 ) d − 2 + f a ( θ 3 ) f b ( θ 4 ) d − 2 2 A 2 + f a ( θ 5 ) f b ( θ 6 ) d − 2 P rx = P tx 3 A 3 � 1 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 9 / 22

Radio Ray Tracing � �� �� f a ( θ 1 ) f b ( θ 2 ) d − 2 + f a ( θ 3 ) f b ( θ 4 ) d − 2 2 A 2 + f a ( θ 5 ) f b ( θ 6 ) d − 2 P rx = P tx 3 A 3 · · · � 1 � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 9 / 22

Path Loss Path loss: Macro-scale function of position & terrain. e.g. Free space, two-ray, HATA/COST231, ITU238, . . . � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 10 / 22

Fading Frequency Time [Credit: Public domain image from Wikimedia commons] Fading: Micro-scale function of many positions and velocities. Treated as function of time. � e.g. Rayleigh, Rician, Weibull, . . . Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 11 / 22

Directivity – Current Models Fading & path loss Node a gain Node b gain P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 12 / 22

Directivity – Current Models Fading & path loss Node a gain Node b gain P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 12 / 22

Directivity – Current Models Fading & path loss Node a gain Node b gain P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 12 / 22

Directivity – Current Models Fading & path loss Node a gain Node b gain P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 12 / 22

Outline Radio Propagation Environments and Directional Antennas 1 Pretty Pictures Measuring Effective Directionality Accuracy of Current Models Estimating Radio Propagation 2 Ray Tracing Propagation Models Directivity Models Directivity and Propagation are not Orthogonal 3 What’s Missing? Modeling 4 Fitting Specific Environments Fitting Types of Environments Relating Signals to Environment Parameters � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 13 / 22

Directivity – What’s Missing? Some f(position) ∗ Some f(time) � �� � + P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) vs. Frequency � �   f a ( θ 1 ) ∗ f b ( θ 2 ) ∗ d − 2 + � � 1 � � �   � f a ( θ 3 ) ∗ f b ( θ 4 ) ∗ d − 2 ∗ A 2 + Time �   � 2 P rx = P tx ∗ �   � + f a ( θ 5 ) ∗ f b ( θ 6 ) ∗ d − 2 �   � ∗ A 3 + �  3  � � � · · · � � = ? � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 14 / 22

Directivity – What’s Missing? Some f(position) ∗ Some f(time) � �� � + P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) vs. Frequency � �   f a ( θ 1 ) ∗ f b ( θ 2 ) ∗ d − 2 + � � 1 � � �   � f a ( θ 3 ) ∗ f b ( θ 4 ) ∗ d − 2 ∗ A 2 + Time �   � 2 P rx = P tx ∗ �   � + f a ( θ 5 ) ∗ f b ( θ 6 ) ∗ d − 2 �   � ∗ A 3 + �  3  � � � · · · � � = ? � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 14 / 22

Directivity – What’s Missing? Some f(position) ∗ Some f(time) � �� � + P rx = P tx ∗ X ∗ f a ( θ 1 ) ∗ f b ( θ 2 ) vs. Frequency � �   f a ( θ 1 ) ∗ f b ( θ 2 ) ∗ d − 2 + � � 1 � � �   � f a ( θ 3 ) ∗ f b ( θ 4 ) ∗ d − 2 ∗ A 2 + Time �   � 2 P rx = P tx ∗ �   � + f a ( θ 5 ) ∗ f b ( θ 6 ) ∗ d − 2 �   � ∗ A 3 + �  3  � � � · · · � � Antenna gain in “off” directions is ignored! = ? � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 14 / 22

An Obvious Problem �������������������������������������������� �������������������������������������������� �������������������������������������������� �������������������������������������������� �������������������������������������������� �������������������������������������������� � Eric Anderson (CU Boulder) Modeling Environmental Effects . . . WiNMee ’09 15 / 22