SWRA725 November   2021 AWR2944

 

  1.   Trademarks
  2. 1Introduction
  3. 2Crossing Interference
    1. 2.1 Performance Analysis for Crossing Interference
  4. 3Localization and Mitigation on the Hardware Accelerator (HWA)
    1. 3.1 Interference Statistics
    2. 3.2 Localization Module
    3. 3.3 Mitigation
  5. 4Summary
  6. 5References

Performance Analysis for Crossing Interference

The level of interference would depend on the distance between the radars (R), the antenna gain in the line connecting the Aggressor Tx and the Victim Rx (AggtxAntGaindB + VicrxAntGaindB), the duration of time during which the chirps ‘cross’ and the Aggressor transmit power (PAggtx).

The main effect of this interference would be to raise the noise floor. The increase of the noise floor after range processing can be calculated as:

Equation 2. N o i s e I n c I n d B =   P I n t e r f e r e n c e + 10 l o g 10 a f f e c t e d A d c S a m p t o t a l N u m A d c S a m p - P n o i s e

Where a f f e c t e d A d c S a m p t o t a l N u m A d c S a m p   is the ratio of the number of ADC samples that were affected by interference to the total number of adc samples. Pnoise is the native noise floor without any interference, and is given by the following equation, where NF is the Victim Receiver’s noise figure, and BandWidthIF is the IF bandwidth.

Equation 3. Pnoise = -174° + NF + 10log10(BandWidthIF)

PInterference is the interference power received at the victim and is given by the following equation:

Equation 4.   P I n t e r f e r e n c e = P A g g t x + A g g t x A n t G a i n d B + V i c r x A n t G a i n d B -   10 l o g 10 4 π R λ 2

Where ƛ corresponds to the wavelength.

As an example, assume the following parameters:

  • Aggressor power (dBm), PAggtx = 10 dBm
  • Aggressor antenna gain, AggtxAntGaindB = 10 dB
  • Victim antenna gain, VicrxAntGaindB = 10 dB
  • Victim Noise Figure, NF = 14 dB
  • IF Bandwidth, BandWidthIF = 10 MHz
  • Wavelength, ƛ = 3.9 mm
  • Distance between Aggressor and Victim = 10 meters
  • Number of samples affected = 10 %

Then,

  • Interferer power, PInterference = -60 dBm
  • Thermal Noise power, Pnoise = -90 dBm
  • Increase in the noise floor, NoiseIncIndB = 20 dB

A 20 dB increase in the noise floor results in missed detections, unless the glitch is located and removed.