1. doc.: IEEE 802.18-09/0090r0 Submission July 2009 Rich Kennedy, Research In MotionSlide 1 Limiting Weather Radar Spurious Emissions – WG SE21 Date: 2009-7-16 Authors:

2. doc.: IEEE 802.18-09/0090r0 Submission July 2009 Rich Kennedy, Research In Motion Introduction The ECC is preparing a Report on the Impact of Radar Spurious Emissions on Other Radiocommunication Services/Systems in WG SE21 Weather radars operating in the 5600 – 5650 MHz band are causing interference far beyond their licensed band For 802.11a devices, weather radar emissions in-band will cause DFS to block channels 120 though 128 Without limits many more channels are unusable Slide 2

3. doc.: IEEE 802.18-09/0090r0 Submission The Report The intent is to set an out of band limit at -100dBc for fixed radars installed after January 1, 2006 –About 200 weather radars around Europe do not meet this EUMETNET wants to set it at -60dBc –They claim very few complaints have been heard –They There have been reports from Finland that these weather radars have interfered with radio links in the 6 GHz and 7 GHz bands –Adding BPFs (and LPFs for the harmonics) to the 250kW radars eliminated this interference –They estimated the cost of the modification to be ~$10,000 July 2009 Rich Kennedy, Research In MotionSlide 3

4. doc.: IEEE 802.18-09/0090r0 Submission The Problems EUMETNET has been active in writing this document and has done its best to limit the impact on radar systems The work on this document needs more inputs from the RLAN community to ensure that 802.11a devices are better protected from weather radar spurious emissions The Wi-Fi Alliance will submit counters to EUMETNET efforts to water down the report Should 802.18 do the same? The next meeting of SE21 in August 27 - 28 July 2009 Rich Kennedy, Research In MotionSlide 4

5. doc.: IEEE 802.18-09/0090r0 Submission July 2009 Rich Kennedy, Research In Motion References SE21(09)31 Annex7 - Working document on Radar spurious emission –(ETSI membership required) Slide 5