April 25, 2017
Output Power and Impact on Microwave Network Availability
As you may have seen, Aviat has been very vocal about the benefits of extra high power (EHP) radios on network designs. Most of these discussions have been about the cost savings benefits of high output power in the form of more distance, smaller antennas, or more capacity.
But what about availability? How much more service up-time can we expect to see with more power?
To answer this question, we took a set of real world microwave designs in the 6GHz frequency band (17.8, 18.1, 28.6 mile paths) and compared path designs using extra high power radios from Aviat and high power radios from the next best supplier. To isolate the availability benefit, the path length, antenna size, modulation/capacity, and other path assumptions were the same for each vendor.
The 9.5 dB system gain benefit you get by using the Aviat radio (yes 9.5 dB!!!) has a significant impact on overall link availability – as you would expect.
The overall availability of a link is calculated based on its probability of withstanding a deep fade. A deep fade can be produced by intense rain, interference, change in the diffraction index of the atmosphere due to thermal inversions that create multipath propagation, etc. The mechanism to increase availability is to have a large fade margin that works as a buffer when this happens. With traditional radios with normal transmit power the usual way of achieving this is using large antennas (the larger the antenna the greater the antenna gain). But with 9.5 dB additional system the fade margin will much greater achieving a higher availability with no need to go to larger antennas.
Figure 1 shows the annual 2-way multipath unavailability in seconds for each design. As rain attenuation is insignificant in 6 GHz only multipath is considered. Figure 1 shows that the EHP radio improves availability on each of the three links by 42s, 81s, and 169s respectively. Further if you extrapolate these results to a 98 hop network and assume some distribution of the hop lengths, you get a total improvement of network availability of 192.7 minutes… or 3.2 hours.
In short, how much can an extra high power (EHP) radio help your availability?
Answer: A lot.
So, if you run a large mission critical network, and you’re not using EHP microwave, your network could unnecessarily be losing upwards of 3 hours of communications. This is very significant, especially if this lost data comes during an emergency or when first responders are facing a life or death situation.
To learn more about Aviat’s EHP microwave radios
*You can request access to the AviatCloud Design App and see for yourself the difference EHP does in your link budgets.