Presentation of Fixed Service Task Group Activities 2001 2002

1
Presentation of Fixed Service Task Group
Activities 2001 - 2002
David EdenRadiocommunications Agency
2
Meetings and Attendance

• Meetings
• 4 meetings were held in the 15 Month period to
  July 2002
• Average attendance was about 26
• Several network operators have withdrawn or
  replaced representatives and higher level
  interest from within RA was evident

3
Objectives

• Establish reason for outages
• To assess possible improvements in
• Specific attenuation
• Path reduction factor
• To examine rain duration statistics
• To update the UK Rain Grid

• To assess sleet as a contributor
• To produce a sleet model if warranted

4
Interim Conclusions

• The existing UK Rain Grid is pessimistic
• This may offer tighter planning options
• But not Nation-wide
• Orographic rain in the NW is close to current
  predictions
• But incidence of convective rain in the SE is
  higher

5
Results/Output 1

• Paper and presentation to RSWG
• TG Proposed and RSWG accepted New Rain Map
  (University of Bath)
• RA converted this map into a form suitable for
  inclusion in corporate software
• TG Proposed that a Sleet model be developed based
  on University of Essex models - RSWG accepted

6
Results / Output - 2

• RA Modelled Sleet in a computable form
• Model presented to ITU-R and awaits verification

7
New Rain Map
8
Map Image
9
Transportable Rain Radar

• Operating at 3 GHz
• Commissioned July 01
• Uses DSP to combat low antenna gain

10
Potential Link Coverage
11
Currently Monitored Links
12
February 7, 2002 Cold - 2 - 6º
13
Taybridge Results 7/2/02
14
Craigowl Results 7/2/02
15
March 10 2002
Temperatures between -2 and 1 degree with sleet
and snow.
16
Taybridge Results 10/3/02
17
Craigowl Results 10/3/02
18
Conclusions

• 8 events in the period 1/1/02-21/3/02 where one
  or more links experience attenuation gtA0.01 due
  to sleet.
• Craigowl experiences more sleet events than
  Taybridge (and both considerably more than
  Winchester/Thorne Hill)
• Many of the extreme attenuation events last
  much longer than predicted by the RAL fade
  duration model.
• Sometimes extreme attenuation is restricted to a
  small number of links indicating spatial
  inhomogeneity in sleet.

19
Sleet Challenges

• Confirm First Quess of form distribution
  through the measurement campaign
• Examine the requirements for dealing with a link
  path transiting the freezing layer
• Complete the interim model for planning

20
Attenuation due to sleet over rain across the UK
21
Immediate Work Programme

• Continue the Southern link monitoring campaign
  to obtain attenuation and fade duration
  statistics
• Continue link monitoring in Scotland to add to
  the Southern campaign and to determine nominal
  values of sleet attenuation

22
Future Role of the Task Group

• Still Under discussion
• Reporting to Head of ERU - Precise mechanism
  unclear
• Perhaps appropriate to combine such a report with
  the RRAC as today?

23
Future Interests of the TG

• Distribution of precipitates over an area for
  BFWA and other point to area systems
• Long term and precise measurement campaigns for
  high availability systems
• Statistical models of of rain events such as
  those posed in Rainmap (Fractal rain)

24
(No Transcript)