One of the things I’ve noticed whenever network availability numbers are being discussed is the speed with which eyes glaze over. Outside of the network planning and operations domain, the difference between 99.99 percent and 99.999 percent availability seems as arcane as a medieval theological debate on the number of angels that can dance on the head of a pin.

However, when it comes to network availability, nothing could be further from the truth. Small differences go straight to the bottom line in terms of the network’s ability to generate revenue.

Consider a typical 23 GHz microwave backhaul link that uses adaptive modulation schemes in the radio with standard ETSI Class 3 compliant 0.6 m (2 ft) diameter microwave antennas. This link is a typical urban environment correctly designed to take into account potential interference from adjacent links.

As an alternative, let’s replace the Class 3 microwave antennas with a Class 4 microwave antenna, such as one from CommScope’s Sentinel portfolio of microwave antennas. The expected availability of both scenarios is shown in the following table:



Modulation (QAM)

Throughput Mb/s (7 MHz channel)

Class 3 Compliant Antenna

Class 4 Compliant Antenna





















At first, there appears to be nothing more than minor differences; however, now consider what these numbers mean in actual network downtime and in actual transmitted data. As the graph below shows, the Class 4 microwave antenna enables the radio to operate in its highest modulation scheme (256 QAM) for more than 32 hours per year longer than the Class 3 microwave antenna with similar benefits on all the other modulation schemes.

In terms of potential traffic, this means that the radio can transmit over 900 Gb a year more. Suddenly, the small differences become significantly more critical.

Putting this into a monetary context, assume that data has a value of around $0.015 per Mb and the potential value of the traffic is approximately $14,000 per annum. Remember, this is for a 7 MHz channel. Use a similar scheme with a 56 MHz channel and we end up with a potential revenue increase an order of magnitude higher at $140,000.

I’m more than happy to concede that 1 Mb over a link does not equate to 1 Mb at the handset. By the same token, drops in modulation schemes will not always take place when the link is carrying maximum traffic. I would, however, suggest that the increase in throughput is high enough to make a significant improvement in the financial performance of the network. This benefit hugely outweighs any slight cost increase from using a Class 4 microwave antenna.

Finally, it’s also worth looking at trends. The graph clearly shows the greatest improvement is with the highest modulation schemes. As radios using 512 QAM or even 1024 QAM become increasingly common, the benefits they bring can best be realized by using antennas with a performance to match, such as Sentinel microwave antennas from CommScope.

Interested in learning how your network can benefit? Check out our Sentinel Antenna Network Analysis Service.




About the Author

Donald Gardner

Donald Gardner is a product line manager within the Microwave Antenna Systems team at CommScope and is based in Lochgelly, Scotland. Holding a Master of Engineering degree from the University of Strathclyde and a Master of Business Administration from the University of Edinburgh, he has been involved in the wireless communications industry for over 20 years. Prior to his current position, Gardner held various positions in quality and engineering within our microwave antenna group. His key expertise includes mechanical and process engineering of microwave antennas and product management of microwave backhaul solutions.

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