We Put the Spotlight on Voice Over LTE (VoLTE)

As one of the most anticipated network technologies, Voice over LTE (VoLTE) has been discussed by operators for years. The expectation was that deployments would start in 2013, but roll-outs in North America were delayed.

VoLTE Logo

Logo courtesy of YTD2525 Blog

Operators have faced a series of issues that include poor voice quality and long call establishment times. Once these problems are solved, it is expected that VoLTE will allow operators to provide  voice and data services using an integrated packet network. As the problems described show, the implementation of VoLTE presents challenges for the entire LTE ecosystem including microwave backhaul.

We have produced a white paper to describe some of the VoLTE requirements that must be met in order to overcome these technical challenges, which must encompass a flexible microwave backhaul as a key factor for a successful transition to all-packet voice and video VoLTE  networks. A brief introduction to VoLTE is presented and then different VoLTE backhaul requirements are described with possible solutions.

Click here to download a white paper on this subject titled “VoLTE and the IP/MPLS Cell Site Evolution”.

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‘My Experience’ with Microwave Radio Systems

Like-a-star-in-a-distant-galaxy-each-users-experience-with-Aviat-Networks-microwave-radio-is-unique-and-positive-13Dec13

Quasar GB 1428, 12.4 billion light years from Earth, a celestial source of enormous X-ray and microwave energy. Photo: NASA’s Marshall Space Flight Center / Foter.com / CC BY-NC

Collectively, we as consumers of high-tech communications systems tend to think very analytically, very logically, about the solutions that form the core of our working lives. In all the fields that we pursue from mobile telecom to public safety to utilities to oil and gas to financial, microwave radio has touched, shaped and framed our worldview. But like a star in a distant galaxy, every user’s experience with microwave radio is unique. No exception to that totality of reality is Ron Beck, president emeritus and past chairman of the Utilities Telecom Council, a trade group dedicated to advocating telecommunications issues for energy companies and associated concerns.

In a recent video, Beck talks about his life with microwave radio for almost 30 years. Starting with analog TDM microwave radio, he has traveled the technology evolutionary path to arrive at the present day systems of digital IP/Ethernet microwave communications. However, before ever touching on any technical considerations, he talks about the people responsible for his and his company’s success with microwave. For utilities applications, Beck feels it is critical that the people he deals with at a microwave solutions provider understand his business. “The (Aviat) sales force understands utility applications; they understand what we need in a radio system,” he says.

Beck goes on to elaborate how Aviat design and engineering groups collaborate closely with his team to deliver exactly the solution that is needed. Service and standards-based technology are very important to him and make microwave radio very user-friendly because “frankly, you don’t have to touch it very much.” See and hear all Beck has to offer below:

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Possibly the World’s Oldest Microwave Link Still in Service

John Lennon was still alive when Aviat's oldest microwave link first went operational in 1980.

John Lennon was still alive when Aviat’s oldest microwave link first went operational in 1980. Photo credit: Roy Kerwood / Foter.com / CC BY

The year was 1980. The Americans beat the Russians for the Olympic gold medal in hockey. John Lennon of The Beatles was killed. Mount St. Helens erupted. The Soviet Union had just invaded Afghanistan. Ronald Reagan was elected president. The hostages were still in Iran. People asked themselves, “Who shot J.R.?” and caught Pac-Man fever. Voyager 1 flew by Saturn and left the solar system. The Empire struck back. John Belushi and Dan Aykroyd were on a “mission from God.” The Clash came calling on London. Led Zeppelin broke up. And Farinon Electric, Aviat Networks’ direct predecessor, put into service a series of analog microwave radio hops for the Canadian province of Nova Scotia’s Department of Natural Resources. The radios in question were the SS2000 model.

The province used them to carry government data traffic for firefighters and police, where data bits were stuffed into 4kHz voice channels. Remarkably, 33 years later, three hops of these SS2000 radios are still in operation, making these, quite possibly, the world’s oldest continuously in-service microwave links.

Farinon SS2000 analog microwave radios were available for sale on eBay as recently as 2011! How’s that for durability?!

Farinon SS2000 analog microwave radio transmitters (but not entire units) were available for sale on eBay as recently as 2011! How’s that for longevity?!

Offering 120, 300 or 600 voice channels on the old 2GHz band, SS2000 radios were considered cutting-edge technology at the time—check out their cool retro-style data sheet—and highly reliable with their ability to provide microwave links despite the challenging weather and difficult propagation conditions of Nova Scotia—snow, ice, sleet, fog…they have it all! As proof, four other SS2000 radio hops were recently decommissioned and found to still be working up to spec as per the original, accepted level of performance. Then there was someone selling SS2000 radios on eBay in 2011!

But we challenge you, our loyal blog readers, to tell us of any even older microwave links that have been in operation for more than 33 years. So if you have an Aviat Networks link, or that from a predecessor company, which is still operating today and was installed before 1980, please comment! We want to hear from you!

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Microwave Backhaul Helps Save Lives in Aviation

English: Auckland International Airport as see...

Auckland International Airport serves a vital role in the aviation industry, and Airways New Zealand and Aviat Networks upgraded its communications network to help maintain it. (Photo credit: Wikipedia)

Few could disagree that aviation remains one of the most vital global industries, due to its capability for transporting goods, people and even ideas thousands of miles in a span of a few hours. Fewer still could argue that aviation is also one of the industries most fraught with danger from equipment failure and human error. Safety is paramount, and clear, continuous communications between airplanes and ground control personnel is at the top of the list for maintaining safety.

What follows is a case study of how an airport traffic solutions provider, Airways New Zealand, expanded airport communications at Auckland International Airport to increase safety with help from Aviat Networks. Together, they implemented five-nines availability microwave radio solutions and futureproof element management system software that will meet the airport’s communications needs for at least the next 10 to 15 years. And all while implementing the network, no disruptions occurred to ongoing airport operations. Overall, the mission-critical communications system of the airport has been enhanced to a failsafe level of readiness.

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On Wall Street Low Latency Microwave Fulfills Faster than Fiber

Happy Holidays and Happy New Year from all of us at Aviat Networks. Just as you are finishing those final gifting ideas for the winter, we would like to share a few thoughts from Travis Mitchell, Aviat Networks director of low latency business development. In the just published article “Microwave Technology for Low Latency Trading Networks” in Wall Street & Technology, Travis clears up the misconceptions that trading technologists may have about microwave communications, many of which have carried over from the age of analog radio and do not apply to digital microwave.

In addition, Travis spells out the advantages that low latency microwave has over fiber optic technology. Two of these are the point-to-point, direct line-of-sight communications between microwave stations and the absolute higher speed microwaves can achieve. In comparison, fiber communications oftentimes do not run directly from Point A to Point B but must instead wind their way around obstacles, burrow underground, climb tall buildings and so on before reaching their destination. This extra distance covered contributes delay to the overall latency experienced by trades sent via fiber as compared to microwave.

Then the immutable laws of nature tell us that microwave communications—even traveling through the atmosphere—approach very close to the speed of light. On the other hand, laser communications traversing the dense medium of fiber optics are much slower than the speed of light—many tens of percentage points slower than the speed of light.

To close, Travis briefly summarizes other factors that go into making low latency microwave networking the choice for traders over fiber, including minimizing the network route, maximizing the distance between microwave hops and using passive repeater technology, when appropriate. For the whole story, see the article. Other resources also include our low latency microwave white paper and low latency webinar replay.

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All-Outdoor Microwave Radios: Site Considerations

One of the great things about the microwave radio market today is the diversity of products available to network operators. But like many situations where there is a glut of options, it tends to put more stress on making the right choice.

An operator looking at products in the microwave radio sector will notice that there are three general categories of product to choose from: all-indoor, split-mount and all-outdoor, and within each, they are myriad different flavors.

All-outdoor radios are the most recent addition to the microwave radio party, and for the sake of easy reference, I’ll refer to them as ODRs (outdoor radios). These self-contained systems incorporate the traffic interfaces, switching/multiplexing elements, radio modem and radio transceiver—all packaged in a weatherproof outdoor housing. By contrast, an outdoor unit (ODU) used in split-mount systems only contains the radio transceiver, which connects to a radio modem embedded in an indoor unit (IDU). In a split-mount radio system, the IDU also provides the traffic interfaces and switching/multiplexing elements.

The rationale for ODRs is straightforward—networks are getting denser, new sites are getting smaller and established sites more densely populated. Space for equipment such as IDUs is at a premium and costs of upgrading sites with bigger equipment shelters is often not viable or possible due to site constraints. As a result, more network devices are being repackaged for deployment outdoors on supporting structures such as towers, walls or masts. Advances in electronics have made microwave radios viable for all-outdoor treatment, so ODRs came into being.

They did so to a fanfare of claims that pointed to fantastic gains in terms of operator TCO (total cost of ownership). No doubt, an ODR can deliver cost benefits, but it is important to fully scope and quantify those benefits, because although ODRs represent simplification in terms of product architecture, most networks have remained stubbornly complex. In practical terms, this means for each type of site in the network an operator needs to closely examine the gains an ODR might generate vs. a split-mount radio, for example. Our experience is that ODRs provide the most operator benefits at sites where:

  • One gigabit Ethernet (GbE) interface is adequate
  • Only a single local device will be connected (such as an LTE basestation)
  • There are no requirements to aggregate traffic from “downstream” sites
  • Out-of-band management facilities are not required
  • Non-protected (1+0) link configuration is adequate

Once operators consider sites with requirements beyond this scope—usually the majority—then ODRs (somewhat ironically) start to generate complexity and cost. This becomes manifest in the form of multiple Ethernet cable runs, multiple power cable runs, multiple PoE injectors, multiple lightning protection devices and, in some cases, the need for a separate outdoor Ethernet switch.

Even at modestly complex sites, the overhead costs ODRs can generate mean that a split-mount radio will often be a more effective option and deliver better TCO, assuming space can be found. On that note it is worth highlighting that IDUs already deployed at such sites are often modular and can be scaled without consuming any additional rack space, and the most advanced fixed (i.e., non-modular) IDUs only consume a half-rack unit of space.

On the surface, the case for ODRs can seem compelling but before jumping in, I would encourage operators to carefully examine how marketing claims translate into meaningful (real) TCO gains.

I am convinced ODRs represent a new and potentially very useful product category for microwave radio, but they are not a panacea; our experience (at Aviat Networks) is that optimum TCO is based on a mix of split-mount and all-outdoor radios (i.e., one “size” does not fit all).

So there you have it, in the right environment, an ODR can offer a winning formula but in other situations, it may not work so well. An old saying comes to mind: Knowledge is knowing a tomato is a fruit, but wisdom is knowing not to put a tomato in a fruit salad.

Next time, we will examine ODRs in more detail, how they differ and how to choose the best option for your network.

Jarlath Lally
Product Marketing Manager
Aviat Networks

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Got Protection? Diversity Schemes and Other Methods

Diversity Schemes and Other Protection Methods for Microwave Radio

Dick Laine, longtime principal engineer for Aviat Networks, delivers one of his patented presentations on microwave networking during an installment of the video blog Radio Head Technology Series.

Microwave radios come and microwave radios go, but the sage advice of Aviat Networks Principal Engineer, Dick Laine, has no end-of-life. In our seventh installment of the very popular video blog Radio Head Technology Series Dick talks about the diversity of diversity schemes and other protection methods available to microwave networking engineers.

Using examples from the radio legacy of Aviat Networks (e.g., Constellation, MegaStar—you must remember these, it hasn’t been that long) and our current microwave networking solutions (e.g., Eclipse, TRuepoint 6500, WTM 6000) he expounds on the past, present and future of protection. From Angle Diversity (one of the earliest diversity schemes used in Line-of-Sight digital microwave) to Hybrid Diversity (HD) and Frequency Diversity (that need licensing waivers to be used in many applications) to comparisons of fiber-like protection methods, Dick covers it all. For example, did you know that a four-dish HD antenna arrangement offers little to no performance improvement over a three-dish HD configuration?

So with free registration to the video series you can have the benefit of all of Dick’s wisdom and nonpareil presentation style on Diversity. You get access to all the earlier videos, too. (Did we mention there are six previous episodes?) And the presentation slides. And the podcast. And all for FREE! Wow! If you don’t see a topic that you think needs to be covered, feel free to submit your suggestion into our inbox. Register today!

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Diversity, Hot Standby and Alarms for Wireless Backhaul—Oh My!

Microwave radio relay tower on Cimetta mountai...

(Photo credit: LittleJoe via Wikipedia)

Do not be Alarmed by this latest video in the Radio Head Technology Series (complimentary registration). For the insider’s perspective on Hot Standby, we will not keep you waiting. Dick Laine, Aviat Networks’ principal engineer, has many informed views on Diversity and relates them in his familiar relaxed presentation style.

All puns aside, Dick covers the multitude of options available in Diversity Schemes (and all their acronyms!). Plus, there is a lot to know about the differences in asymmetrical splitters for digital radios and their analog predecessors. Turns out there is no point in using symmetrical splitters in digital microwave radios. Even a heavily asymmetrical split provides as much protection as a symmetrical split but it avoids 2-3 dB in fade margin losses, providing significantly more uptime.

And if there is anything you need to know about Alarms, Dick takes a fine-toothed comb to the subject and teases out the details, providing context for the strategy of how they function in keeping your wireless communication network online. Dick will also tell you how improvement in digital radios has led to large gains in recovery time when radios in a Hot Standby arrangement are switched and quadrature relock can now essentially be avoided. On errorless switching, although it has greatly benefitted microwave radio usage, Dick will tell you the importance of early warning alarms to it.

So make no mistake, Dick is your information source for all things microwave radio—wrap your head around it!

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Protection and Diversity: 100 Percent Uptime the Goal

English: BT Thornhill microwave radio tower

The BT Thornhill microwave radio tower above demonstrates a Space Diversity protection scheme with its parabolic antennas placed apart from one another (Photo credit: Peter Facey via Wikipedia)

Traffic disconnect is unacceptable for most microwave systems, especially for homeland security and utilities. But Aviat Networks Principal Engineer Dick Laine says that it is economically unviable to have a microwave radio system that provides absolutely 100 percent uptime to accommodate every possible traffic downtime scenario. He adds that towers, waveguides and all other hardware and infrastructure would have to be completely bulletproof. This is true of every telecommunication system.

However, with protection schemes and diversity arrangements in today’s wireless communication solutions, microwave transmission can get very close to mitigating against long-term traffic outages (i.e., > 10 CSES, consecutive severely errored seconds) and short-term traffic outages (i.e., < 10 CSES).

In pursuit of the 100 percent uptime goal, Dick goes over many of the strategies available in the newest video in the Radio Head Technology Series, for which there is complimentary registration. For example, there are many approaches to protection, including Hot Standby and Space Diversity. In particular, Dick points out Frequency Diversity has advantages over many protection schemes, but few outside the federal government are able to obtain the necessary waivers in order to use it. Hybrid Diversity uses both Space Diversity and Frequency Diversity to create a very strong protection solution. A case study outlining Hybrid Diversity is available.

Other concepts Dick covers in this fifth edition of Radio Heads includes error performance objectives, bit error rate, data throughput, errorless switching, equipment degradation, antenna misalignment, self-healing ring architecture and something called the “Chicken Little” alarm.

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What is More Susceptible to Rain Outage, Vertical or Horizontal Radio Signals?

English: A map of the world divided into Inter...

The world is divided into separate International Telecommunication Union regions. In many regions of the world, ITU methods of calculating rain outage are most commonly used. In other regions, such as North America, the Crane model is used more often. (Image credit: Wikipedia)

Ever wonder which antenna polarization is more susceptible to rain outage? Vertical? Horizontal? Which should you use for very long hops?

What would you do besides add extra fade margin to mitigate rain outage? Design a shorter path or use a lower frequency band?

Aviat Networks’ microwave radio guru, Principal Engineer Dick Laine, tackles these tricky questions and others in the latest episode of our Radio Head Technology Series of videos.

Dick also talks about rain outage—as calculated by ITU using a simple scientific calculator, or computer programs (Starlink) that use the Crane model. He goes through an ITU-R availability calculation in one example, noting specifically about rain attenuation calculation above and below 30 degrees latitude. Dick then proceeds into a deep dive on calculating outage when you know the fade margin, followed by a discussion on the Crane rain attenuation model.

Aviat Networks invites our readers to register to be added to our Radio Heads distribution list to get notified of new Radio Head Technology Series releases and links to replays.

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