OVERCOMING DENSE DEPLOYMENT CHALLENGES

Martins Dzelde

Senior Sales Engineer

Agenda

SAF Link planning team – success story

Interference countermeasures

Link planning and interference analysis

Antennas

Using Spectrum Compact for Interference Detection

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SAF global footprint map

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Link planning success story

Largest MW network in Lagos, Nigeria.

More than 200 SAF links deployed in area of approx. 15 x 20 miles

Detailed path analysis for interference for max frequency re-use

Calculated for best antenna size, Tx power for minimal number of channels

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Interference Countermeasures

Measures to decrease the influence of interfering signals:

• other RF channel (or band)

• change of antennas

• higher discrimination(high, ultra-high performance antennas etc.)

• larger antenna size

• change of polarization

• Attenuation by obstruction

• new routing

Tx power adjustment of interfering radio

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Link planning & Radio signal propagation

Basic planning data

• Network configuration

• Location of terminal stations

• Capacity/interface demand, initial and predicted

• Radio-frequency bands available

• Existing radio sites in the area

• Performance and availability requirements

Frequency allocation guide Actual distance varies

depending on rain-zone, tower heights, availability requirements.

8 GHz10.5 GHz

18 GHz

23 GHz

7 miles

14 miles

30 miles 45 miles

Frequency bands Path Length Typical application

23 GHz and above < 7 miles Access network

18 GHz 14 miles Short haul, within cities

10.5 GHz 30 milesLong haul,

over the sea8 GHz 45 miles

< 5 GHz 37-50 mile, > 60 miles

Tx band allocation

Determination of Tx band allocation at each site:

• Low band (LB) Tx < Rx• High band (HB) Tx > RX

HB

LB

LB

LB

LB

LB

LB

HB HB

HB

HB

HB

HB

HB

LB

Fresnel zone• Radio signal does not propagate as a singe beam.

• Nearly half of the Rx signal energy travels through the Fresnel ellipsoid.

• Any obstruction within the Fresnel zone can cause obstruction loss.

• Fresnel radius depends on frequecy band and link distance

• Higher frequency bands have smaller Fresnel ellipsoids

Antenna Architecture

The lower the frequency the longer wavelength

Hence for low frequency bands need large antennas to maintain the same antenna gain

2 GHz

5 GHz

10.5 GHz

25 GHz1ft = 0.3 m

2ft = 0.6 m

3 ft = 1.2 m

12ft = 3.7m

FIXED GAIN APPROX. 35 dBi

Antenna Theory

Small size antennas

Antennas sized up to 4ft have wider main beam and more evident side lobes

Typical error – antenna is aligned on side lobes

Large size antennas

Bigger antennas with higher gain have a narrow main beam and less relevant sidelobes.

Typical problem for installation crew –finding the first signal from the far side site.

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Antenna alignment

Ensure both antennas are aligned to the main lobe

Avoid alignment on a side lobe or a strong reflected signal

Antennas: Class 3 vs Class 4

Improved side-lobe suppression and F/B ratio

Better frequency reuse:

• Improved interference discrimination• up to 67% more links: 10 links of C4 vs 6 links of C3 on the same site

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Antenna upgrade

Replacing existing antennas with higher performance antennas which side lobes are more isolated thus received reflected signal through side lobes will be weaker

Shielding example

Use natural obstacle for shielding antenna from multipath or other interfering signal

Spectrum Compact for site analysis

Interference Countermeasures

Measures to decrease the influence of interfering signals:

• other RF channel (or band)

• change of antennas

• higher discrimination(high, ultra-high performance antennas etc.)

• larger antenna size

• change of polarization

• Attenuation by obstruction

• new routing

Tx power adjustment of interfering radio

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• Smallest fully functional spectrum analyzer

• Functionality of three devices: spectrum analyzer, power meter, antenna alignment tool

• Control the work quality of subcontractors

• Saving spectrum scans for future reference

• Quick interference detection

• Easy RF troubleshooting

• No hidden costs – all updates, PC SW included in the price

Spectrum Compact

Case study – mobile operator

LMT Network

Location: Latvia, entire area

Link distance: 600 m up to 35 km

Frequency bands in use: 6, 13, 18, 23, 26, 32, 38 GHz

Antenna diameter: 0.3 m-1.8 m

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In the field – using handheld directional antennas for higher gain demands

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Horn type J0AA0610HG02 J0AA1115HG01 J0AA1724HG01 J0AA2640HG03

Covered frequency range, GHz

5.925-11.000 10.700-17.000 17.000-26.500 26.500-40.000

Typical Gain, dBi 14.5-18 19.5-20.5 21.0-21.5 20.5-21.5

Spectrum Compact for finding Free Channel

Free radio channel selection

Useful in license-free bands e.g.

17GHz and 24Ghz radios

Useful functionality in countries with

weak or no spectrum Regulatory supervision

With the Spectrum Compact, it is possible to determine whether there is the necessary guard band for transmission.

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Spectrum Compact for Interference detection

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Way better sensitivity and bandwidth resolution than built-in spectrum analyzers in a radio

Market leading sensitivity -105 dBm/MHz

SAF Tehnika © 2017, www.saftehnika.com

Thank you!

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