Reply to Comments on WCA Petition for FCC Regulation Change in the 57-64 GHz Band

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks Submission Title: [Reply to Comments on WCA Petition to Change FCC Regulations Governing the Unlicensed 57 – 64 GHz Band] Date Submitted: [July 2005] Source: [Gregg Levin] Company [BridgeWave Communications Address [3350 Thomas Road, Santa Clara, CA 95054] Voice: 408 567 6999], E-Mail: [GreggL@bridgewave.com] Re: [Reply to contribution by Gilb July 2005 commenting on WCA Petition] Abstract: [Replies to the comments contributed by James Gilb] replies-to-gilb-wca-comments-ppt 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. Change from PD to EIRP • For historical reasons, many Radio Regulations written in units of Power Density at 3 meters*** Agreed • 9 mW/cm2, measured at 3 meters, is equivalent to saying EIRP = 10 W*** Not true – there is no EIRP limit in the current rules as transmitters using large-aperature antennas have increasingly large EIRPs, yet have decreasing 3-meter PD levels

3. continued • Changing to EIRP would need to be done throughout all parts of Radio Regulations*** Part 15 2.4GHz and 5GHz already based on EIRP – 60GHz rules are the exception • Changing from PD to EIRP need not be done “to ensure compliance with . . . Section 15.255(b)(1) . . . in the near field.”*** 3-meter PD does not make sense when in near field

4. continued • In fact, Sec. 15.31 states that Part 15 equipment >30 MHz must be measured in the far field.*** Sec 15.31(3)(b) says that “All parties …are urged to use these measurement procedures. Any parties using other procedures should ensure that such other procedures can be relied on to produce results compatible with the FCC measurement procedures.”

5. Change from PD to EIRP (cont’d.) • PD measurements only make sense in the far field (FF).*** Agreed 8. Current regulations specify PD measurements at 3 m.*** Agreed 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.*** Grossly overstates PD at 3 meters when 3 meters is in near field 10. Except for the virtue of clarity, there is no good reason to make this change.*** Clarity is good. Technical correctness is also good.

6. 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!*** EIRP is NOT power nor PD. EIRP itself does not cause interference. Power and PD increases are on the order of 13dB.

7. 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)*** 2X distance increase = 4X building pairs that can be connected. • But so does the interference range!*** Oxygen attenuation reduces interference range by 14-16dB per kilometer. Walls, windows, and antenna directionality significantly reduce risk to indoor systems. Users typically use the smallest antennas possible for the required range – energy reaching indoor systems will typically be approaching threshold. P-to-P links are no worse than other low-gain antenna users of the band.

8. 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.*** Yes, but E-Band systems are much more costly, will remain more costly, and coordination procedures are beyond acceptability for enterprise users.

9. 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.*** 13dB increase is not “ultra-high” power • We recommend continuation of moderate power levels and a publicly-declared call sign.*** Power increase request is on the same order as window reflective losses. Window links under proposed rules will be comparable to P-to-P indoor links under existing rules.

10. 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! *** Request that TG3c: - Set up liaison with WCA committee - Allocate time to seek compromises that support needs of both PAN and P-to-P uses - Hold off on FCC letter until above steps are taken