A presentation on RF survey, showing how survey of a cell site is done, how a microwave link is established, and how to perform the LOS survey for clearing the obstacles in between the links

1. session : 2011-12
Guided By:-
Prepared By:-
Mr. virendra Verma
Harish Kumawat
H.O.D. (E.C.)

2.  Sharing site survey
 New site survey
i) Sharing site survey:-
-coverage capacity
ii) New site survey:-
- GBT, RBT, RTP
- Nominal point
- Range (100-200m)
- Site options

3.  Survey of land
-size
-tools
compass, GPS, measuring tape, camera,
binoculars, ultimeter, inclinometer, maps, 10 or 50
meter tape measure, Site survey document
 Deviation P1 r
known as side shift. 0 P3
P2

4.  Coordinates
latitude and longitude
 AMSL
 Complete Address of proposed site
 Accessibility
- nearest city, highway, railway
station, airport

6.  Tower height
 GSM height
 Orientation
 BTS (indoor/outdoor)
 Wiring distance
 Hop length
 Shelter
 Layout of proposed site

7.  GPS
 GSM
 Access photos
 Plot photos
 Para photos
 Sector photos
 Cluster photos

8.  GPS photo

9.  GSM photo

10.  Sector photos

11.  Cluster photos

12.  Access photos

13.  Para photos
- 12 photos
- at every 30 degrees
30º 270º
330º

14.  Line of sight survey
 Connectivity of two sites
 Clearing links
 carried out physically checking the terrain
between the hop
and selecting the sites for acquisition.

15.  Collect Nominals of proposed site and those of the nearest
locations to which customer proposes the LOS connectivity &
Verification
 Record latitude, longitude, building data, obstruction data
and surrounding terrain data on the LOS Survey template.
 Generate LOS Path Profile for the proposed Link using Path
Loss 4.0
 Generate LOS report for the proposed Link using Path Loss
4.0.Conduct physical survey of the hop to identify any field
obstructions and verify the LOS path profile

17. Microwave Links
Basics
The preferred media when building new
access network links
High capacity transmission links
from 2x2Mbps to 16x2Mbps, 34Mbps
Pros: Cons:
 low operating costs  needs frequency license
 easy to install  environment dependant
 flexible link quality (e.g. rainfall)
 quick & reliable solution  LOS not always available
Repeater
station
Terminal Terminal
station A station B

18. Microwave Links
Types of MW
• Long Haul Radios: ~ 30 - 80 km
2 GHz, 7 GHz
• Medium Haul Radios: ~ 25 - 45 km
10 GHz, 13 GHz, 15 GHz
• Short Haul Radios: ~ 5 - 30 km
18 GHz, 23 GHz, 26 GHz, 38 GHz,
• Nokia Metrohopper: < 1 km
57 GHz
(uses oxygen absorption in air to
limit range)

19. Microwave Links
Radio Link Availability
• Microwave outages
– equipment failures
• use protected equipment
– caused by nature
• temporary failures
• self-recovery
• use protected connections
• Examples of natural outages:
– heavy rainfall zones:
• most severe in upper bands (2..3dB/km)
• significant above 10 GHz
– multipath fading
• problem with lower bands

20. Microwave Links
How to Avoid Interference
• Use the highest available frequency band
• Attenuate the Tx power to a minimum just
to meet the required availability
• Locate dishes as low as possible with
maintaining the required LOS
• Use big dishes
• Use different polarisation
• Select your channel(s) carefully
• Maintain High-Low -rule on hub sites
• Try to get similar received signal levels at
hub sites

21. Microwave Links
LOS Check
LOS Methods
 Balloon method
 Mirror reflection method
 Using binoculars
 Route track method

22. Microwave Links
Fresnel Zone
• Line-of-sight path needed between both nodes of
a microwave link
• Keep 1st Fresnel zone clear of obstacles
• nth Fresnel zone: Ellipse around direct path, where
path difference to direct line is n* /2.
1st Fresnel zone
2nd
3rd
d
b
d [km]
b 274 [ m]
f [ MHz ] Radius for n-th zone = b * sqrt(n)

23.  Curvature of earth
= (d1*d2)/(12.75* k)
where k=(eff. Earth radius/true earth radius)
 RF effect of fresnel zone
fresnel zone= 17.32*[√{(d1*d2)/(D*f)}]
 Path loss
 Transmitted and received power
 Transmission line losses
 Frequency of operation
 Antenna gain
gain= {17.8+20log(D.f)}

24.  Earth bulge
Antenna Height = Earth Buldge + Maximum Obstacle Height+ Fresnel Zone

25.  To establish links
 Feasibility of studies
 Upgradation of existing links