1. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 1 Near Horizon Partial Solid Angle Metrics Notice: This document has been prepared to assist IEEE 802.11. 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2005-9-21 Authors:

2. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 2 Abstract Presentation 11-05/0944 described a simple propagation direction probability model used by the cellular industry to process Total Radiated power (TRP) and Total Isotropic Sensitivity (TIS) radiation pattern data into terms referred to as Near Horizon Partial Radiated Power and Near Horizon Partial Isotropic Sensitivity. This presentation investigates the geometry of some typical 802.11 implementations to evaluate the usefulness of these metrics for TGT.

3. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 3 Overview Introduction Near Horizon Partial Solid Angle Metrics Geometrical Optics Office Building Implementation Example Conclusions

4. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 4 Introduction In a given operational environment, only a portion of the radiated energy of a wireless device will typically come into play when evaluating the available link budget. Portions of the radiation pattern propagate in directions that are statistically never likely to reach the associated AP/client when the device is in a location where the level of those signals would be of concern. By weighting the data in the radiation pattern based on basic features of the environment, a better estimate of the resulting link behavior can be obtained.

5. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 5 Introduction Concepts like Mean Effective Gain (MEG) are elaborate statistical models for evaluating this behavior. Near-Horizon Partial Solid Angle metrics are a simplified model applicable when the horizontal distance between associated devices is several times longer than the vertical separation distance. This is commonly the case when devices are at the limit of their range where the link budget terms would become critical. There are plenty of other ways to process radiation pattern data to evaluate different scenarios.

6. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 6 Near Horizon Partial Radiated Power (NHPRP) and Near Horizon Partial Isotropic Sensitivity (NHPIS) –CTIA defined specification. –Cell towers exist along the horizon. –Energy radiated up into space or down to earth is lost to network. –Similar situation exists in layout of an 802.11 network on one floor of a building. Near Horizon Partial Solid Angle Metrics

7. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 7 Method numerically reduces the data integrated from that for TRP/TIS by discarding data near the top and bottom of the pattern. –Angles of ±45°, ±30°, and ±22.5° typically used, but any range can be chosen. Near Horizon Partial Solid Angle Metrics

8. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 8 Evaluating the three NHP solid angles as defined, we can represent them as simple angles in a planar elevation drawing. The solid angle is symmetrical around the vertical axis. Geometrical Optics

9. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 9 The vertical geometry is relatively simple, assuming you’re primarily looking for performance between DUTs on the same floor. Geometrical Optics

10. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 10 The figure below illustrates the first five transmission paths between the DUTs, ignoring reflections from vertical surfaces (walls) and/or objects in area. Geometrical Optics

11. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 11 There’s probably not much reason to consider reflections much beyond second order (two surfaces). –Added path loss just due to increasing distance significantly reduces the contribution of these rays at the DUT. –Most surfaces will be well below perfect reflectors. Can probably assume at least 3 dB loss per bounce and still remain conservative. Angle formulation for these paths: –Direct:  = atan((h 1 - h 2 )/d) –First Order floor:  = atan((h 1 + h 2 )/d) –First Order ceiling:  = atan((2h 3 - h 1 - h 2 )/d) –Second Order:  = atan((2h 3 - h 1 + h 2 )/d) –Second Order:  = atan((2h 3 + h 1 - h 2 )/d) Geometrical Optics

12. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 12 Typical multi-story office building has ~10-12’ stories. –Assume 12’ per floor, APs at 11’ high, and clients at 3’ high (8’ delta). Office Building Implementation

13. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 13 Assuming 12’ per floor, APs at 11’ high, and clients at 3’ high yields: Office Building Implementation

14. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 14 Assuming 12’ per floor, APs at 11’ high, and clients at 3’ high, the paths for a 32’ separation are: Office Building Implementation

15. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 15 Placing the Near Horizon angle indicators we see that –All paths are in the ±45° range –All but one are in the ±30° range –The two paths most likely to have the strongest signal are within ±22.5° Fewest obstructions in a cubicle environment, etc. Office Building Implementation

16. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 16 Outdoor implementations (light posts, etc) much simpler since there’s only one reflected path possible. –Direct:  = atan((h 1 - h 2 )/d) –Ground reflection:  = atan((h 1 + h 2 )/d) Assume 20’ tall poles with clients still at 3’. Office Building Implementation

17. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 17 Conclusions The concept of Near Horizon Partial Solid Angle metrics appears to be as applicable to 802.11 devices as it is to cellular devices. At the separation distances where TRP and TIS become important (limits of the link budget) in largely planar layouts such as floors of an office building or an outdoor installation, the terms NHPRP and NHPIS are likely to be better representations of a device’s OTA performance capabilities than the full TRP and TIS. Other partial solid angle values around the poles could be used to judge likelihood of bridging across floors. NHP values are just different ways of looking at the same data to learn more about your DUT.

18. Doc.: IEEE 802.11-05/1009r0 Submission September 2005 Dr. Michael D. Foegelle, ETS-LindgrenSlide 18 References 11-05/0944r0, “OTA TRP and TIS Testing ”, M. Foegelle