How to increase capacity in microwave networks with the new normal
There are new traffic patterns emerging, including more traffic in areas that do not normally feature such high peaks. That’s why it’s important to consider what can be done to boost transport capacity. Here’s a look at the options…
The first step is of course to monitor the performance of the network and identify links where the capacity is close to configured max capacity. This can be done from the management center and does not require any site visits. Key performance indicators to look at are things like utilization counters, e.g the actual Ethernet utilization versus the configured maximum capacity of the radio-link. An inventory check of which links are configured with static modulation but have HW capable of adaptive modulation can also be helpful. QoS settings are also vital to verify that they are configured in a good way since this will impact the availability for the priority traffic if it is wrong. The next step is to analyze if the current restrictions on capacity are due to configured maximum modulation, installed capacity licenses or the channel bandwidth. The recommended action in the next step depends a lot on this analysis. In general an inventory check of the hardware at the site is needed to see what capabilities can be used. Finally a check on which links have ATPC enabled is helpful since Automatic Transmit Power Control will support both lower power consumption as well as securing that adaptive modulation will perform at its best.
Making better use of existing equipment
A friend and I once had a brief argument about which type of binoculars was the best ones for watching wildlife in the forest, she quickly killed the discussion about technical features by stating the obvious, the one you had brought with you was superior to any other that might be technically better but still at home!
The same simple argumentation can be used on our current situation, whatever increase in capacity that can be achieved with the already installed HW by remote changes are the easiest to get! Therefore the second step is to try to resolve the capacity issue using the existing hardware at the site. The good news is that most modern microwave links have had the ability to support adaptive modulation for almost a decade now. This means that many links could potentially support more capacity than they are currently configured for; typically a 30-150 percent increase can be achieved.
The main reason for not having used it so far has been the fear that the availability of that additional capacity is lower than what traditional planning suggests it should be. Most existing microwave links have a planned-for availability of between 99.995 and 99.999 percent – in other words, a link might lack capacity for five to 26 minutes per year. With adaptive modulation, the link might not necessarily be down during this time, although the capacity could be limited.
This also creates the possibility to add more capacity – but with even lower availability. If for example, you accept that the new greater level of capacity offers say 99.9 percent availability, it would mean that you would have the current capacity for eight hours and 45 minutes per year and have more capacity the rest of the time. So in short, you do not lose what you have but you get more most of the time.
One extra benefit of adding network capacity using adaptive modulation is that it can be done on a remote basis. This requires a reconfiguration and possibly additional capacity licenses as well, but no site visit is necessary. It will not reduce the current level of service availability either. To achieve the best possible functionality, adaptive modulation should always be combined with the correct quality of service configuration, ensuring that priority traffic can always use the capacity available.
In some cases, just increasing the modulation will not be enough owing to a combination of heavy traffic and hops that are too long. In such cases it may be possible to add output power by adding a high power license to the radio (which can enable higher modulation) or reconfigure an existing Link Aggregation Group(LAG) set up to a radio-link bonding configuration with much higher efficiency. Header compression is also a feature that in some networks can add up to 10 percent more capacity when enabled. Just like radio-link bonding, this does not have any negative impact on the availability of the hop and should therefore be considered whenever possible.
In some cases, it might be possible to get approval from the frequency authorities to exchange the used channel for one that is twice as wide – a 56MHz channel say, instead of a 28MHz channel. In many cases, such reconfigurations can also be made remotely, and can result in up to twice the capacity, but if the proposed solutions do not help, it may be necessary to add new equipment to the site.
Adding equipment to the site
For sites that are already equipped with dual polarized antennas, and only one polarization is being used, adding additional radios can be a fairly quick way to upgrade capacity. There is no need for new antennas or antenna alignment; a radio, cabling and modem are simply added to existing infrastructure, and the extended capacity is applied to existing radio-link bonding groups whenever possible.
When new antennas are needed, it may be a good time to consider adding an E-band radio as a multi-band booster, which will typically have a 30cm or 60cm antenna and can support up to 6km hops with Gbps capacity at 99.9 percent availability. (See this previous blog post for further information.)
For longer hops, one option may still be to use wide channels (56/80/112MHz) in a higher frequency band (18-42GHz) than the original link to achieve the same capacity increase at 99.9 percent availability.
If there is spectrum available in the lower bands, a third option could be to replace a single short-haul radio with a split long-haul solution, adding up to eight channels over one antenna with very limited transmission losses . This can also be combined with a multi-band booster solution in 18-42GHz spectrum for even more capacity.
Optimized usage of the existing network
The suggested actions outlined above are based on using network investments that have already been made even more efficiently. This means monitoring usage, adding capacity on existing hardware, and complementing existing installations with multi-band booster capabilities since this is normally the most cost-efficient solution. If you are interested in learning more about how to get the most out of your existing microwave equipment, visit our Microwave multi-band booster page. And while you’re there, don’t forget to check out our virtual tool, which allows you to play around with frequency, capacity, hop length and more. Try it yourself!