Project: IEEE P802.15 Working Group for Wireless Personal Area Networks

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks Submission Title: [Comments on WCA Petition to Change FCC Regulations Governing the Unlicensed 57 – 64 GHz Band] Date Submitted: [July 2005] Source: [James Gilb] Company [SiBEAM, Inc.] Address [39300 Civic Center Drive, Fremont, CA 94538] Voice: [(510) 745-7334], E-Mail: [first initial last name at sibeam dot com] Re: [WCA Petition RM-11104 Filed with FCC, September 2004; and a presentation by Gregg Levin to IEEE 802.15.3c, dated July 14, 2005] Abstract: [The WCA has proposed a change in the regulations that govern the use of the unlicensed 57 – 64 GHz band; the changes would dramatically increase the power injected into this band, thus increasing interference for low-power WPAN systems. There are good arguments to oppose the WCA proposal, and this presentation advances those arguments.] Purpose:[Contribution to 802.15 TG3c at July 2005 meeting in San Francisco, California] Notice:This document has been prepared to assist the IEEE P802.15. 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 P802.15.

2. Objectives • Comments on WCA petition of September 30, 2004, on 57 – 64 GHz rulemaking • Maintenance of current FCC protections and regulations in 57 – 64 GHz license-exempt band • Seeking 802.15.3cTG support in opposing WCA petition

3. Why is there interest in 60 GHz Band? • License – exempt operation in 57 – 64 GHz band • Very high data rates possible • Small form factors • Low – cost systems derived from low – cost electronics • Short – range wireless LAN and wireless data delivery products

4. Current 60 GHz rules • License-free operation under Part 15.255 • Rules designed around wireless LAN usage • 10 W EIRP • 500 mW peak power limit – 15.255(e) • 3-meter power density limits – 15.255(b)(1) • 9 mW/cm2 average • 18 mW/cm2 peak • Transmitter IDs for access point coordination – 15.255(i)

5. Background of WCA Petition • Insertion of high – power point-to-point transmitters into the 57 – 64 GHz unlicensed band • Properties of proposed transmitters similar to those recently approved for fee-bearing, coordinated service at 71-76 GHz, 81 – 86 GHz, and licensed service at 92 – 95 GHz (WT Docket No. 02 – 146; RM – 10288; FCC 03 – 248) • Rules for access to these 13 GHz are tailor-made for point-to-point links

6. Elements of WCA Petition • Specification of Transmitters using EIRP instead of Power Density • Request for a large increase in EIRP limits for unlicensed 57 – 64 GHz transmitters • Request for exemption for “window – mounted” point-to-point links from call sign requirement

7. Change from PD to EIRP • For historical reasons, many Radio Regulations written in units of Power Density at 3 meters • 9 mW/cm2, measured at 3 meters, is equivalent to saying EIRP = 10 W • Changing to EIRP would need to be done throughout all parts of Radio Regulations • Changing from PD to EIRP need not be done “to ensure compliance with . . . Section 15.255(b)(1) . . . in the near field.” • In fact, Sec. 15.31 states that Part 15 equipment >30 MHz must be measured in the far field.

8. Change from PD to EIRP (cont’d.) 7. PD measurements only make sense in the far field (FF). 8. Current regulations specify PD measurements at 3 m. 9. For high-gain systems with FF > 3 m, 9 mW/cm2 at 3 m can be extrapolated to 2.2 mW/cm2 at 6 m, 1 mW/cm2 at 9 m, and so on. 10. Except for the virtue of clarity, there is no good reason to make this change.

9. Request for Increase in Power Limits • WCA has asked for increase in EIRP limits from 40 dBm (10 W) to “82 dBm less 2 dB for every dB that antenna gain is below 51 dB.” • This could result in an increase in antenna gain and transmitter power, up to an EIRP of 63,000 Watts!

10. Request for Increase in Power Limits • What are the benefits? An increase in range. How much? • Estimates are that, for most US cities, range approximately doubles in all cases (see Appendix A) • But so does the interference range!

11. Appendix A: Sample Range Calculationsfor Outdoor Links3 • Taking rainfall data into consideration. Assumed receiver sensitivity of -90 dBm, consistent with a 5 dB NF and 1.25 GHz bandwidth, Rx antenna gain of 32 dBi, 20 dB SNR requirement, and 5 nines availability. • Interference range calculated for dry air, assuming that a competing signal20 dB below the Rx sensitivity could cause interference. • Reference: FCC filing, dated November 29, 2004 by Rory Van Tuyl.

12. Rx Leq < < < WPAN System Interfering high-power Tx Intended Tx (40 dBm EIRP) 10 meters (typ.) Interference Potential for Indoor Links • Assume interior losses from reflections of 10 dB, except for case of GA = 30 dBi. • Equivalent Path Loss = PL = PT – 40 dBm – LR • Equivalent Distance Ratio Leq = distance interfering high-power transmitter must be from WPAN Rx to effect same power as intended WPAN Tx • For all cases, assume WPAN transmits at 15.255 limit of 40 dBm EIRP. Oxygen absorption included at 15 dbm/km 5. Point-to-point link must be > 200 meters away to interfere with only the same signal power as the intended WPAN transmitter!

13. * Distance interfering radiator must be away from intended receiver to effect noise equivalent to thermal channel noise Oxygen absorption included at 15 dB/km. R = (PL)-1/2l/4p * Interference Potential for Indoor Links (cont’d.) • Comparison of interfering high-power signal with thermal channel noise • Assumptions: • 1 GHz of signal bandwidth • Noise figure of receiver = 8 dB • Antenna gain of receive = 15 dBi

14. Request for Increase in Power Limits • The nearby 71 – 76 GHz band actually offers greater range (lack of oxygen absorption). • This band also allows operation with EIRP up to 55 W • Therefore, we recommend that The Commission make no changes to the existing EIRP for the 57 – 64 GHz band.

15. Request for Exemption to Call Sign Requirement • The WCA argues in favor of “window links” with high EIRP. • There is great potential for interference on both the receiving side as well as the transmitting side. • Window glass can reflect significant amounts of incident radiated power (see Appendix B). • Conservatively, an outgoing beam could scatter back into a room a signal only 10 dB weaker than the transmitted beam. • The combination of ultra-high power and lack of call sign sets the stage for high indoor interference. • We recommend continuation of moderate power levels and a publicly-declared call sign.

16. Appendix B: Window Reflections • Representative measurements of reflections off normal glass1 Complex Permittivity2 • These values are reasonably uniform over various kinds of glass 1. ＜January. 200４> Doc.：IEEE802.15-04/003-00-mmwi <Toshiyuki Hirose>, <Siemens K.K.> 2. ＜March. 200４> Doc.：IEEE802.15-04/0094r0-mmwi Akira Akeyama, NTT-AT

17. Reflectivity with and without Window Shades Ref: Sato, et. al., “Measurements of Reflection and Transmission Characteristics of Interior Structures of Office Building in the 60-GHz Band,” IEEE Trans. on Antennas and Propagations, Vol. 45, No. 12, Dec. 1997, pp. 1783 – 1792. • Conclusion: ~10% reflectivity is a good (and optimistic!) approximation under a variety of conditions

18. Elements of Letter* in Circulation • Market for an IEEE standard-based consumer product (WPAN) will be considerably larger than that for outdoor point-to-point equipment. Efforts by IEEE to develop a standard attest to this market potential. • WCA objections to limited link distances at 60 GHz can be addressed with the FCC’s opening of the 70 GHz and 80 GHz bands. • Hence, WCA should consider moving to these bands to capitalize on more than 10 GHz of aggregated bandwidth and longer link distances than at 60 GHz. • WCA claims that the proposed rule change will not cause significant potential for interference are problematic. • On the contrary: at the power levels requested, links mounted indoors would exhibit significant interference, both by direct transmission and by reflected radiation from windows. * IEEE P802.15-05/0308r0

19. Request for Support of P802.15-05/0308r0 • We request an endorsement of this letter and that it be sent to the FCC. • Thank you!