Noise in Wireless Systems Produced by Solar Radio Bursts

1
Noise in Wireless Systems Produced by Solar
Radio Bursts
June 1, 2001

• B. Bala, L. J. Lanzerotti, D. E. Gary and D.
  J. Thomson

2
Data
June 1, 2001

• type .. ..
• compiled by ...
• period ..
• frequency range ...
• reporting stations .
• solar cycles covered..

• Solar radio bursts
• NGDC of NOAA, Boulder
• 19601999
• 18 MHz92.5 GHz
• around the globe
• full cycles 20, 21, 22, declining phase of
  19, ascending phase of 23

3
Biased? Possibly, due to
changes in
June 1, 2001

• the number and location of observatories
• the frequency of observation
• instrumentation leading to improved sensitivity
  of detection

saturation of receivers on large events
4
Duplicate events
June 1, 2001

• defining an event using 12 min time window and
  labeling
• selection of data with peak flux density gt103 SFU
  in the frequency range 120 GHz
• selection of the event with highest peak flux
  density for entries with the same eventlabel and
  frequency

5
Why 12 min?
June 1, 2001
a trade off between elimination of real
events and inclusion of duplicate events

• multiple detection of an event is possible only
  while the event existed
• eliminating events within this interval should
  remove duplicate events
• however, independent events occurring within 12
  min will also be eliminated
• other 50 has duration longer than 12 min
• longer window will include more duplicate events

6
Noise in wireless communication
June 1, 2001

• receiver noise at ambient temperature is
  kT 3.8x10-21 W/Hz (T 273 K)
• -174 dBm for a bandwidth of 1 Hz
• receiver power PR G l2 F/8p, where l is
  wavelength, G is receiver gain, F is flux
• k T B GB l2 10-22/8p
• 900 MHz and G 10, F 960 SFU this is more
  than twice the thermal noise power

7
Discussion
June 1, 2001

• 1000 SFU can be taken as a context threshold
  for interpreting the statistical results
  presented
• such or larger events are likely to occur every
  1020 days or so over a decade
• also depends on the orientation of the antenna
• an antenna at a given cell site is most
  susceptible 3 hours morning and evening

8
Conclusion
June 1, 2001

• on average, one might expect solar noise
  interference at a cell site every 4080 days