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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”. Increase Desired Field Strength.

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Presentation Transcript
Realignment position
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


Increase desired field strength
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


Improve im performance tradeoffs
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


Receiver standards
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


Increase ps decrease cmrs power
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


Recommendation

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


Oobe reduction
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


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