What Does it Take to Get the Most out of Your Wireless Backhaul?

Wireless tower in Ghana. Photo credit: Rachel Strohm / Foter.com / CC BY-ND

Many wireless operators, such as MTN in Ghana, need to optimize management of their networks and Aviat can help with products, services and software capabilities. Photo credit: Rachel Strohm / Foter.com / CC BY-ND

Wireless backhaul operators, both mobile phone networks and others carrying dedicated traffic, face the constant issue of maximizing the functionality of their systems.

In the emerging markets around the world, the pressure can be most intense. Wireless network reliability, availability and capacity all need to be increased. Customer expectations are on the rise, and operators must take the appropriate steps to meet and exceed them.

In working with MTN Ghana, Aviat Networks recently completed an implementation to increase network visibility (i.e., intelligence) by close to one-third. Aviat’s professional services experts designed the mobile operator’s backhaul links for high capacity and resiliency. Using ProVision, Aviat’s leading network management software, MTN Ghana can now administer its wireless backhaul efficiently and effectively with a reduced level of manpower.

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Low Latency Microwave Crosses Europe for the First Time


Successful financial trades depend on ultra low latency microwave networks. Photo credit: francisco.j.gonzalez / Foter.com / CC BY

Germany is well-known for its autobahn highway system, where there are no official speed limits. Now there is a new high-speed network that traverses Western Europe from Frankfurt in Germany to London in the UK.

In addition, you may have read elsewhere in recent weeks about low latency microwave networks being constructed in the United States in support of the financial markets. The busiest route there is between the financial centers in Chicago and New York, where microwave can shave off 5 milliseconds off the transmission time along the 700 mile (1,000 km) route when compared to fastest fiber network (13 milliseconds). This saving directly equates to revenue for trading houses that are able to leverage this speed advantage.

In the United States, planning and deploying a point-to-point (PTP) microwave network is relatively predictable and straightforward: acquire sites and avoid interference from other network operators. Where PTP wireless networks cross state boundaries, a network operator need only deal with the national telecom regulator, the Federal Communications Commission (FCC), when obtaining required licenses to operate the microwave system.

But in Europe, this is a very different matter. While trans-European fiber networks have been a reality for many years, a microwave route like London to Frankfurt must traverse several national borders, forcing operators to deal with multiple regulators, with complex negotiations needed for microwave paths that cross national boundaries. For this reason very few—if any—microwave networks of this type have been built, up until now. However, the opportunities offered by the combination of the new low latency sector, along with the performance advantage of microwave over fiber, have now made the case  for these kinds of networks compelling enough to outweigh the challenges, and costs, of planning and implementing them.

For a low-latency microwave network servicing the financial sector on the London-to-Frankfurt route, there are a number of major challenges beyond just identifying and securing suitable sites and coordinating frequencies. The difficulty of planning a long trunk route is also greatly exacerbated by going through the densely urbanized region of Western Europe. This results in a constant iteration between finding the right route, identifying accessible sites, and securing required microwave frequencies. To be successful you need all three—a site on a great route is useless if no microwave spectrum is available. All the while, there are other competing providers all trying to complete the same route in the fastest time possible—not only in latency terms, but also time to revenue.

This poses huge potential pitfalls in having to take the long way around, requiring additional sites and links, if a site is not available. The added latency caused by any such deviation could kill the entire project. This race is like no other in the microwave business—whoever is fastest wins first prize, and it is winner take all in this competition. The potential revenue for the London-to-Frankfurt low-latency path is quite staggering, even on a regular day, but on busy days when the market is volatile the potential can be much higher.  Operators can plan on recouping their total investment in the microwave network in well under a year. Then once you have the most direct route, compared to your competitors, your problems may not be over, so it can come down to squeezing those extra few microseconds, or even nanoseconds, out of your equipment.

On this particular route there is also one significant natural barrier to contend with—the English Channel. There are only a few ways across that are short enough to allow a reliable microwave path, space diversity protection is a must and only a few towers are tall enough to support these distances. Even though there are no obstacles over the channel (apart from the occasional container ship), towers need to be high enough to allow the microwave signal to shoot over the bulge of the earth. Again, securing tower space at these sites is critical to success, but also obtaining the right to use one or more of a finite pool of available frequency channels, otherwise fiber may be needed across this stage, adding latency. One group even took the step of purchasing a microwave site in the Low Countries to secure it precisely for this purpose.

London to Frankfurt will only be the start for low latency microwave networks in Europe, as there is always a need and an opportunity to provide competitive transmission services to other financial centers throughout the continent. The winners will be those with the speed and agility to quickly seize these opportunities, along with working with the right microwave partner who can help them with the intensely complex business of planning and deploying these trans-national networks, and who can also supply microwave systems with ultra-low latency performance.

We will have more to say publicly on this topic in the near future. Or if you prefer not to wait that long, we would be more than happy to have a private conversation about low-latency microwave with you.

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Building Ultra-Long IP Microwave Links


Ultra-long microwave links between backhaul towers enable long-distance telecommunications in the Mojave Desert. Photo credit: °Florian / Foter.com / CC BY-SA

Designing and engineering microwave radio networks has always been challenging and a bit of an art—especially when they are ultra-long point-to-point wireless networks. In an article published February 25, 2013, Aviat’s solutions architect Charles Dionne outlines some of the key considerations that need to be made when designing and building these ultra-long microwave backhaul links for point-to-point wireless networks.

The article on RCR Wireless provides an overview and detailed checklist of the relevant items for designing ultra-long point-to-point wireless microwave links including:

  • Site selection
  • Frequency selection
  • Antenna size
  • Atmospheric conditions

Readers will take away more than just a laundry list of potential pitfalls; they will gain an enhanced appreciation of the very specialized skills and thorough understanding of microwave technology that is necessary for successfully implementing point-to-point wireless microwave backhaul.

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How is Buying a Wireless Network like Buying a Boat?

Downeast style charter boat Wreck Valley

Buying a network is like buying a boat in that you do not really know what you need/want until after you have bought it. (Photo credit: Wreckvalle via Wikipedia)

Think about this phrase carefully: “Buy your second boat first.” Lately, I have been thinking of that phrase, which I once read in a boating magazine, and how it parallels some of the thinking processes wireless operators go through when making their technology and product decisions.

Often, when it comes to boating, you do not know what kind of “boat” you want or that you are even in the market. You show up to the boat show and are overwhelmed by the number of models, features, prices, etc.

To make a long story short, you end up picking something that is shiny/new, fits your near-term budget and matches how you envision the experience. What you did not know is how the “boat” rides in the water, how well it will perform with your children trailing in the water in an inner tube, how it is at storing all your swag, how roomy it really is once you add your friend’s family and the dog, etc. It is only after you get to know these things and “boating” in general that you start to realize what it is that you really want.

But now, you are stuck for at least a few years since—as you can imagine—you cannot easily trade in a “boat” that you have owned for just a short period of time. You need to stick it out until it makes sense financially, all the while watching “boats” you really want zipping around on the lake. If only you could go back in time and buy your second boat first. This experience draws parallels to wireless network buying decisions for a few reasons:

  1. Depreciation of wireless networking assets—much like a boat, the network does not pay for itself for a number of years down the road. Memories and the fun on the boat is really the only way to assign the boat a monetary value, but a wireless network is similar in that its usage is paying down on the investment
  2. What’s shiny/new is not always what you actually need—don’t be emotional. You need to understand what it is you really want to build toward. Stop thinking about how you can get by on the cheap to satisfy a relatively short-term, emotional goal
  3. Experience/expertise—whether buying a boat or buying a wireless network, find someone you can trust, someone who has done it before and has the experience to work with you on the complete package, the solution and total cost of ownership. Test-drive your friend’s boat for a day or take him to the boat show

Suffice to say you really cannot predict the future, but you should know where you want to go and where you want to be. Knowing you should be thinking about how to build the right network first just makes sense.

Steven Loebrich
Director, Partner and Solutions Marketing
Aviat Networks

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Diverse Wireless Network Topologies Cost Savings

To compare how different wireless backhaul network topologies perform under the same operating scenario, let’s analyze how a traditional hub-and-spoke and a ring configuration compare in connecting the same six sites (See table below). For the hub-and-spoke configuration, each cell site is provided 50 Mbps capacity in 1+1 protection. With five links and no path diversity, full protection is the only way to achieve five nines reliability. In this configuration, 10 antennas are employed, which average a large and costly 5.2 feet in diameter. Total cost of ownership for this six-site network is close to $700,000 for five years.

TCO Comparison by Topology

TCO Comparison by Topology

For a ring design for the same six sites, throughput of 200 Mbps is established to carry the traffic for each specific hop and any traffic coming in that direction from farther up the network. Designed to take advantage of higher-level redundancy schemes, the ring configuration only requires antennas that average 2.3 feet in diameter, which are much lower in cost compared to the antennas in the hub-and-spoke configuration. And even though the ring configuration requires 12 antennas and six links, its overall TCO amounts to a little under $500,000 over five years—30 percent less than TCO for the hub-and-spoke design for the same six sites.

This comparison is based upon deployments in the USA, where most operators lease tower space from other providers.

Gary Croke
Senior Product Marketing Manager
Aviat Networks


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Why Bigger is not Always Better for Mobile Backhaul!

Terrestrial microwave radio system with two an...

Terrestrial microwave radio system with two antennas employing space diversity. (Image via Wikipedia: Photo credit David Jordan)

Antenna gain is directly related to the size (diameter) of the antenna, and wireless transmission engineers looking for more system gain to improve link performance on long or tough paths in frequency bands below 10 GHz may resort to using very large antennas with diameters of 12 feet (3.7 m) or more. However, bigger is not always better. In fact, large antennas should only be used under the most unusual of circumstances.

Use of large, oversized antennas was commonplace during the 1960s and 1970s, for analog FM-FDM heterodyne microwave communication high-capacity links operating in the L6 GHz band. This was for good reason. Communications paths consisting of multiple radio links required very high receive signal levels, and fade margins of up to 50 dB, on each link to meet end-to-end noise objectives. The large antennas helped cut baseband thermal noise by more than 3 dB, which is half that of smaller antennas. Many of these paths were relatively short and many of these analog wireless links employed frequency diversity, so higher fade margins were needed to reduce outage—especially in N+1 hops. This reliance on large antennas is often still prevalent in the minds of many wireless transmission engineers.

Today’s Digital Microwave Systems

In contrast to old analog systems, digital microwave operates essentially error-free (i.e., with a bit error rate of 1 in 1,013 transmitted bits), even with much smaller fade margins. Adequate path clearance, optimal selection of diversity arrangements using smaller antennas and the precise alignment of antennas are far more effective to ensure that error performance objectives for microwave communications are met.

Big Antennas = High TCO

So because big antennas are not really needed to ensure high path availability, they do directly impact the total cost of deploying and operating a microwave link, namely:

  • Wind Loading—There is more wind loading because of the larger surface area. A 12-ft antenna has 45 percent more loading (e.g., 1,400 lbs wind load in a 70mph wind) compared to a 10-ft antenna (e.g., 980 lbs wind load). This means the microwave tower needs to be stronger to be less susceptible to the sway that results in antenna misalignment. Stronger towers mean more costly new towers, or expensive upgrades to existing towers
  • Beamwidth—Beamwidth of a 12-ft dish is 25 percent narrower compared to a 10-ft antenna, which further increases the tower’s rigidity requirements and thus cost
  • Non-Diversity vs. Diversity—Large 12-ft antennas are sometimes justified by assuming that the single large dish is more cost-effective and/or has performance characteristics as good as two smaller diversity dishes. A single 12-ft dish with its 1,400-lb single-point wind load—and narrower beamwidth—puts far more stress on a structure than dual 8-ft diversity dishes with a distributed wind load of 1,260 lbs (2x630lbs) and much wider beamwidths. Smaller diversity dish arrangements also increase the wireless link’s performance by reducing multipath outage by more than 80 percent compared to a single 12-ft dish deployed in a non-diversity hop
  • Antenna Decoupling and Alignment—The smaller beamwidth of larger antennas also increases the difficultly to align accurately, and the risk of antenna decoupling due to angle-of-arrival variations during nocturnal atmospheric (k-factor) changes. Antenna decoupling, directly proportional to path length, is increased on those longer paths in difficult geoclimatic areas that attract the use of 12-ft dishes. It can be a death spiral—the longer, more difficult paths that attract the use of larger, narrower beamwidth antennas are those that are even more sensitive to the resulting geoclimatic conditions!
  • Aesthetics—Bigger isn’t better when deploying dishes on towers, buildings and—especially—mountaintop sites, due to aesthetic concerns, building/tower owners’ concerns and local planning limitations. These can often be mitigated by using smaller antennas
  • Deployment Costs—The overall deployment cost differential between a single 10-ft and 12-ft antenna can exceed $10,000 when transport, installation and ancillary hardware are taken into consideration, and this does not include the potential cost of added tower strengthening and increased monthly tower lease charges

So before you consider using large 12-ft+ antennas, think again and consider the bigger picture. You may well end up spending a lot more money for a path that may perform more poorly than it would have if smaller antennas had been used.

For more tips, we’ve also included some wireless transmission engineering guidelines for antennas and other wireless equipment.

Stuart Little
Director of Corporate Marketing, Aviat Networks

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Managing Wireless Networks with Element Management Systems

Management of Complexity

An EMS can be thought of as managing all the elements in a complex network, keeping them all in balance. Image by michael.heiss via Flickr

Managing a wireless network is essential. Radios, routers and third-party add-ons control vast amounts of valuable user data. Any wireless network downtime damages the user’s business and the operator’s long-term reputation. Thus, operators need a powerful but easy-to-use element management system (EMS) to monitor and administer all the disparate elements in their wireless communication networks.

Also, operators should be able to manage complete networks from a user-friendly interface, which must provide all the necessary information for fast network management system decision-making. And this system must be capable of complete standalone operation or being integrated into an operational support system using NorthBound Interfaces (NBIs).

Other additional functionality in the form of event management and notifications capability is also necessary in an EMS for wireless networks. An EMS should inform wireless operators about network events and device failures and let them to diagnose problems and apply network updates remotely. This reduces the time between a fault occurring and the fault being repaired. It may even allow a repair to be completed before a wireless link fails completely. For day-to-day management, operators need an EMS that can:

  • Deploy, manage and auto-discover wireless equipment—including all Aviat Networks devices, partner products and third-party devices
  • Display an entire network at once, via one of several map views
  • Provide an overview of network events
  • Deliver notifications of important network events
  • Enable analysis of network events, device events and performance data
  • Generate detailed reports on all aspects of a network
ProVision Screen Shot

The ProVision EMS solution can manage all Aviat Networks wireless solutions, partner wireless equipment and third-party devices from a user-friendly GUI.

Fortunately, such a carrier-class EMS solution does exist. Aviat Networks develops its ProVision EMS based on customer demand and continues to upgrade it as per user requests and requirements. For customers, implementing ProVision is vastly more efficient than developing an in-house EMS, saving time, resources and money. Aviat Networks EMS solutions are the most cost-effective way to manage wireless solutions. Aviat Networks works closely with customers to make sure that ProVision is user-friendly. The goal is that ProVision EMS allows operators to manage their networks proactively—rather than reactively—and with reduced network operating costs.

Look for future blog posts on must-have EMS data features and stats on operators using carrier-class EMS.

Mick Morrow
Sr. Product Marketing Manager, Aviat Networks

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