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Realignment Position

Realignment Position

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Realignment Position

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  1. Realignment Position • Generally favor • Concentrates IM closer to the source frequencies • Additional measures required regardless of realignment • Comments about specific plans to be part of “Reply Comments” Talking Points TR8 Private Radio

  2. Increase Desired Field Strength • Current rules (40 dBm) based on mobile coverage, not portable • Insufficient field strength for portable based systems • Mobiles antennas • Have Gain • Low cable loss • Greater height above ground • Portable antennas • Less efficient • Body absorption • Low height above ground • Portables go where mobiles cannot • In-building Talking Points TR8 Private Radio

  3. Improve IM Performance - Tradeoffs • Decrease sensitivity for better IM performance • Requires increased field strength to compensate • Current PS subscriber radios are better than cellular • Deployments are the difference • Noise limited vs. Interference limited designs • Increases battery drain • Additional filtering increases physical size • Other system tradeoffs Talking Points TR8 Private Radio

  4. Receiver Standards • Project 25 specifies 60 dB ACRR for adjacent 12.5 kHz channel. • Required narrow receiver bandwidth • Limits on how much power a receiver can handle compared to the desired • Non linearity produces energy on frequency • OOBE energy already on frequency Talking Points TR8 Private Radio

  5. Increase PS, decrease CMRS power • Two interference mechanisms • Intermodulation • Currently the biggest contributor • Requires reducing interferer and/or increasing desired • OOBE • Must be controlled as well • Dominant once IM is resolved • TIA 700 MHz recommendations will be reiterated • -126 dBm/6.25 kHz bandwidth inside PS spectrum • Per licensee at a site • When known or anticipated, design can include mitigation Talking Points TR8 Private Radio

  6. DesiredPublic Safety (dBm) 40 (50,50)* , -94 dBm 45 (50,50), -89 dBm 50 (50,50), -84 dBm * Refers to FCC R6602 terminology for indicating location, time probability CMRS upper limit (dBm) -40.0 dBm on the ground -37.5 dBm on the ground -35.0 dBm on the ground Control via PFD within 0.7 km (0.4 mi) of CMRS site IM mitigation Limit OOBE -126 dBm/6.25 kHz bandwidth in public safety spectrum OOBE mitigation Only required where Near/Far potential exists Recommendation Talking Points TR8 Private Radio

  7. OOBE Reduction • Has to occur at source • D/U established in space • All subsequent elements contribute the same loss/gain to the desired signal and to unwanted OOBE • Allow additional external filtering beyond transmitter certification to accomplish • Existing stations required to add filtering to meet this requirement • Limit to each licensee at each site to produce a maximum of 3 dB reduction in sensitivity due to producing the equivalent noise as the victim receiver’s internal thermal noise Talking Points TR8 Private Radio