doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 1 WRAN Operation Using Fractional TV Channels IEEE P Wireless RANs Date: Authors: Notice: This document has been prepared to assist IEEE 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 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 Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson 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 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at >

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 2 Abstract Several WRAN proposals have been submitted to IEEE that include provisions for fractional TV channel operation when that TV channel is occupied by licensed Part 74 devices (e.g. wireless microphones). Here we briefly discuss the implications of such operation and present considerations for mitigating interference to the Part 74 devices.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 3 WRAN Operation Using Fractional TV Channels Several WRAN proposals have been submitted to IEEE that include provisions for fractional TV channel operation when that TV channel is occupied by licensed Part 74 devices (e.g. wireless microphones). IEEE previously considered this possibility and concluded that such operation should be avoided. Here, we outline the technical issues that must be addressed before fractional TV channel operation would be permitted.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 4 WRAN Operation Using Fractional TV Channels What are the problems with fractional TV channel operation when wireless microphones are occupying that channel? Basically there are two problems: –WRAN sideband noise will cause interference and reduce the operating range of the microphone –Strong WRAN carriers will create inter-modulation (IMD) products with other signals at the microphone receiver, causing audible interference

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 5 WRAN Sideband Noise During previous sessions, IEEE determined the level of out-of-channel WRAN emissions required to protect incumbent services from interference (e.g. TV and wireless microphones; reference Functional Requirement Document). Based on these determinations, the group determined that it would be technically infeasible for WRAN systems to operate on TV channels adjacent to those in use by TV stations or wireless microphones. Note that this restriction only applies locally to the area where interference would occur.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 6 WRAN Sideband Noise For WRAN systems to fractionally use TV channels occupied by wireless microphones, WRAN emissions falling within the portion of the channel being used by a Part 74 wireless microphone must be attenuated to a level below –115 dBm (measured in a 200kHz BW) If this condition cannot be met, the WRAN sideband noise will introduce interference into the wireless microphone receiver, resulting in disruption or noise bursts.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 7 Effect of Fractional TV Channel WRAN Operation on Wireless Microphone Frequency Planning Wireless microphone systems must be frequency coordinated to enable interference-free operation. The complexity of a wireless microphone frequency plan grows exponentially as the number of in-channel transmissions increases due to the generation of IMD. Frequency planning must also take into account transmissions in adjacent channels, including those of other services. In-channel WRAN transmissions will present special challenges, since all energy will fall within the passband of the wireless microphone receiver.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 8 Conclusions WRAN operation using fractional TV channels in use by wireless microphones poses technical challenges. In most cases, multiple wireless microphones will be operating simultaneously in a TV channel, limiting the amount of additional spectrum that could potentially be recovered by a WRAN system for its use. Avoiding operation in an occupied channel is the most robust solution from an interference prevention standpoint.

doc.: IEEE /0019r0 Submission January 2006 Ahren Hartman, Shure IncorporatedSlide 9 Conclusions WRAN systems only need to avoid an occupied TV channel in the immediate vicinity of the wireless microphone system. WRAN systems must not cause interference to licensed incumbent users.