Microwave Backhaul for Public Safety LTE

US Navy 031026-M-4815H-029 Fire fighters from ...

(Photo credit: Chance W. Haworth via Wikipedia)

Public safety agencies will soon experience a dramatic improvement in communications capabilities enabled by advances in technology. New broadband multimedia applications will give first responders and commanders alike far better situational awareness, thereby improving both the effectiveness and safety of all personnel charged with protecting the public.

The specific technology, now mandated by the U.S. Federal Communications Commission (FCC) for all new emergency communications networks, is Long Term Evolution, or LTE—a fourth-generation (4G) broadband solution. The FCC has also allocated licensed spectrum to ensure the best possible performance in these new networks. These FCC rulings support the goal of achieving an interoperable nationwide network for public safety agencies.

The FCC chose LTE based on its proven ability to support voice, video and data communications at remarkably high data rates that were previously only possible with wired links. Although there will be some differences in a nationwide public safety network involving capacity and coexistence with Land-Mobile Radio communications, lessons learned from LTE’s deployment in large-scale commercial mobile operator networks will help ensure agencies are able to achieve the FCC’s goal cost-effectively.

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4G Upgrade Path Drives Backhaul Migration in Kenya

Safaricom's Internet Broadband Dongle (with SI...

Burgeoning WiMAX and 3G data traffic from subscriber devices such as Safaricom’s Internet Broadband Dongle (with SIM Card) are driving the mobile operator to migrate from TDM to hybrid microwave backhaul. (Photo credit: whiteafrican via Flickr)

Migrating legacy mobile backhaul networks that were designed for TDM traffic to add support for high-speed Ethernet data for 3G and 4G mobile technologies is one of the biggest challenges for operators worldwide. Each case is unique and poses its own quirks and potential pitfalls. Mobile operators must juggle new technologies, cost pressures and the need to maintain existing services or risk driving customers to the competition.

For Safaricom, the leading mobile operator in Kenya and one of largest in all Africa, the case involved preserving its E1 capacity for voice calls and simultaneously adding Ethernet/IP bandwidth for burgeoning 3G and WiMAX data traffic. As many mobile operators have done in the past, Safaricom built its network over time. Many parts of the network are still legacy 2G TDM technology. However, things are changing rapidly, with 3G subscriber numbers up 85 percent in 2011 year over year.

Many of these subscribers are consuming ever-increasing amounts of data bandwidth. Safaricom’s TDM based backhaul, making use of Ethernet-to-E1 converters, is finding it hard to keep up with demand. To help resolve the situation, the operator called on Aviat Networks, one of its incumbent solution providers. Using its market leading hybrid radio solution, the modular Eclipse microwave networking platform, Aviat Networks enabled Safaricom to add IP data capacity as necessary while keeping E1 capacity for voice calls.

In addition, the stage has been set for Safaricom to make the eventual migration to all-IP backhaul. With the modular Eclipse platform, it can transition on its own schedule. For more information, read the complete Safaricom case study in the frame below or download the PDF:

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42GHz: A New Global Standard for Wireless Backhaul?

Parabolic antennas

With ever-increasing demand for spectrum in fixed services, FWCC has endorsed opening up the 42GHz band as a new global standard for microwave backhaul. (Photo credit: Miguel Ferrando via Wikipedia)

An ever-increasing demand for spectrum has recently turned focus on the 42GHz band. Initially opened in some European countries following the development of ECC REC(01)04, the recently published ECC Report 173 states 12 countries have opened this band including Germany, Norway, Poland, Switzerland and the United Kingdom. In the U.K., this band was part of a wider auction of fixed service bands in 2010, with three operators being granted blocks of spectrum in the 42GHz band as a result.

Building on this growth there is a move to make this band global and earlier this year saw the publication of ITU-R Rec F.2005, which in effect promoted the aforementioned CEPT recommendation to global status. Aviat Networks has been lobbying key regulators to open this band. We are eagerly awaiting a consultation from Canada and responses have already been submitted to recent consultations from France and Ireland containing considerations regarding opening this band. The process is also underway in Finland and Sweden to open up this band. Recently our attention has turned to the United States and whether the FCC will open this band for use by the fixed service.

Back in autumn 2011, Aviat Networks raised this topic within the FWCC (Fixed Wireless Communications Coalition) as the first stage of a petition of rulemaking to the FCC. At first there was only a lukewarm reception to our idea as there was concern that the FCC would refuse the request out-of-hand as some previously released spectrum below 40 GHz is underutilized and, therefore, why is more needed? We pointed out that much of this spectrum (e.g., 39 GHz) was block-allocated by auction and thus has not been readily available to all users and that the licensees have underutilized the spectrum. There is a growing need for spectrum that can be licensed on a flexible, site-by-site basis, and this is reflected by the fact that there are no underutilization issues in bands such as 18 and 23 GHz, which are licensed in this manner. It is no coincidence that auctioned bands tend to underperform in terms of efficiency and utilization. So, undeterred, we forged ahead and this resulted in the production of a FWCC petition to the FCC in May 2012. The FCC has recently placed this petition on public notice, per its procedures. This is a great success for Aviat Networks and our commitment to seeking more spectrum for the fixed service, but the story has not ended here as can be seen from a recent blog entry from the FWCC.

Aviat Networks will continue work with the FWCC to ensure that the FCC gives this proposal full consideration and, having learned important lessons from past spectrum allocations, we will lobby for a flexible approach to the licensing model.

Ian Marshall
Regulatory Manager
Aviat Networks

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The Modulation Arms Race: A Case of Diminishing Returns

English: A standard Quadrature Amplitude Modul...

A standard Quadrature Amplitude Modulation constellation (non-gray code) diagram showing a demonstrative 4-bit binary code pattern. (Phase offset and amplitude values may not represent those used in real life) (Photo credit: Chris Watts via Wikipedia)

There’s a new arms race in the microwave industry, and it’s over who can claim support for the highest QAM level. Now two vendors are out in the market fighting it out over who had 2048QAM first, yet go back a little more than 12 months and 512 or 1024QAM had barely hit the market. We even are seeing mentions of 4096QAM in some conference presentations. We here at Aviat Networks view these advances as a good thing for our industry, but this heavy marketing of 2048QAM does no one any favors, as it focuses purely on only one aspect of high modulationscapacityand ignores several other aspects that need to be understood, namely:

  • Capacity improvement diminishes with every higher modulation step
  • High modulations come with much lower radio system performancerequires shorter hops and/or larger antennas
  • High modulations are much more sensitive to interferencemakes link coordination difficult (if not impossible)
  • High modulations need higher Tx power, increased phase noise and linearityincreases radio design complexity cost

So as with most things that are presented as a cureall, higher order modulations are a useful tool to help operators address their growing backhaul capacity needs, but the catch is in the fine print. Operators will need to look at all the tools at their disposal, of which 1024/2048QAM is a useful option, albeit one that will require very careful planning and strategic deployment. In general, operators need practical solutions for capacity increases, as detailed in “Improving Microwave Capacity“.  In fact, speaking of practicalities, the real challenges with LTE backhaul has very little to do with capacity…as detailed by this article. For the complete “Modulations Arms Race” article, click here.

Stuart Little
Director, Corporate Marketing
Aviat Networks

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Utilities Must Work Closely with Wireless Vendors on Smart Grid

At the UTC Telecom 2012 show, Aviat Networks was able to meet with utilities regarding their networking needs. Bottomline, utilities must work closely with their wireless backhaul and other solution providers in order to implement smart grid capabilities.

UTC Telecom 2012 is the annual show of the utilities industry in North America. New technologies and products were displayed to help the industry with its latest challenges. Also various utilities shared their experiences in implementing new networks to deliver leading edge smart grid capabilities.

The show was extremely well attended with a myriad of vendors including many consulting firms. The key message that I took away was the need for utilities to work very closely with their equipment vendors—especially wireless backhaul solution providers—and consultants to implement next generation networks capable of handling the multitude of applications associated with smart grid.

It was interesting to hear from AltaLink about the findings from its extensive lab testing and network implementation:

  • How far do you drive MPLS into the network?
  • How do you “tweak” the MPLS settings to accommodate microwave radios adapting in modulation?
  • What kind of MTU sizes need to be passed and how well do vendor capacities relate to the particular MTU sizes?

BC Hydro talked to the two critical issues it is struggling with: end-to-end management and security across the entire network. Balance the needs/wants of the IT dept., the communications dept. and various internal administrative groups is a real task! Some people think that only the commercial mobile networks must deal with overzealous users demanding unlimited bandwidth to address their video/gaming/voice applications…what happens when all the utilities’ departments find out that there is bandwidth available?!

Aviat Networks’ Eclipse Packet Node radios and skilled network engineers can help you find the right solution for your smart grid implementation. Whether your utility is just starting to look at the issues or ready to buy the critical components of the network, Aviat Networks is able to help.

Randy Jenkins
Director of Business Development
Aviat Networks

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Dick Laine’s 4 Keys to Successful Transmission Engineering of Microwave Links

Dick Laine, Principal Engineer, Aviat Networks

Dick Laine, Principal Engineer, Aviat Networks

Transmission engineering of a microwave link requires creativity and skill. So if you are looking for inspiration as well as high-quality wireless engineering instruction look no further than the “Radio Head Technology Series.” Radio Heads is a collection of videos and podcasts featuring our very own Dick Laine. Dick is arguably the most experienced microwave engineer in the wireless communication business, having spent more than 50 years working with microwave radio from its inception—here at Aviat Networks and our predecessor companies (e.g., Farinon, Harris MCD).

Dick has been involved with nearly every aspect of RF transmission, microwave link and network transmission design, and the effects of geoclimatic conditions on transmission of voice and now IP radio data packets.

In his own unique style, Dick has been teaching basic and advanced concepts for digital microwave transmission in seminars and training classes worldwide. Students who have taken his classes return years later eager to get a refresher from Dick and to hear about some of his great adventures in Asia, the Middle East, Africa and in the Americas.

In the first Radio Heads video titled “Check List for a Successful Microwave Link,” Dick explains the four key objectives or requirements for a well-done microwave link design along with “check list” items that the project manager or transmission engineer evaluates for proper design and deployment of a digital microwave link. If you have not already signed up for this video series, register to view the content.

If you find this video of value, please pass along the information to your friends and colleagues via Facebook, Twitter, LinkedIn or your other favorite social media network.

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Coverage Maps for New Wireless Spectrum Available to Fixed Services

United States radio spectrum frequency allocat...

United States radio spectrum frequency allocations chart. The FCC has freed 650 MHz of spectrum to increase sharing possibilities for 7GHz and 13GHz bands. (Photo credit: United States Department of Commerce employee via Wikipedia)

As we blogged last summer, the FCC has released 650 MHz of new wireless technology spectrum for Fixed Service wireless communication technology operators. Now Comsearch, a leading provider of spectrum management and wireless engineering services in the US, has highlighted this issue in its latest online newsletter, with an article that includes some very informative coverage maps showing the zones where the new bandwidth is available.

These maps are excellent at conveying the limitations of the newly released spectrum for microwave link applications in the 7 GHz (6.875–7.125) and 13 GHz (12.7–13.1) bands. After taking into account the zones that are reserved for existing Fixed and Mobile Broadcast Auxiliary Service (BAS) and the Cable TV Relay Service (CARS) users, these new bands are only available in about 50 percent of the US land mass covering only 10 percent of the population.

What do you think? Should the FCC loosen the spectrum sharing rules even more for 7GHz and 13GHz bands? Take our poll and tell us:

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The Wireless Transmission Blog is #One

Today is the 1st anniversary of this blog!

It has come a long way in its first year and it is still the only blog that specializes in wireless transmission!

In the past year the blog has received more than 45,000 visitors. Topics have ranged from “Small Cell Mobile Backhaul: The LTE Capacity Shortfall” to “Just How Recyclable is my Radio?” and it has the luxury of a wide range of contributors.

The post that received the most hits was “What is Asymmetrical Link Operation?” and the post that received the most comments was “The World’s Longest All-IP Microwave Link”?
Thanks to the contributors and the people who took the time to comment.

We are looking forward to more insightful posts in 2012 including a daily commentary from Mobile World Congress in February. Stay tuned.

Aviat Networks

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The Impact of Streaming Video on Wireless Network Services

Video call between Sweden and Singapore, on So...

Sustained video streaming, such as a video call over a mobile network, strains the stat mux paradigm of oversubscribing Ethernet microwave backhaul. However, proper management can ensure a consistent, high-quality user experience can be maintained. Image via Wikipedia (author: Kalleboo)

Mobile backhaul networks today support Ethernet microwave transport for 3G and 4G wireless technology services alongside legacy 2G and 3G TDM-based microwave equipment. However, as late as 2009 these wireless network services were solely TDM transport. One of the primary benefits of moving to Ethernet microwave transport has been the inherent statistical multiplexing (stat mux) gains. Stat mux relies on the fact that not everyone is “talking” at the same time and when they do, their IP radio packet sizes are variable, whereas networks based on TDM have to be provisioned statically for peak rates to individual wireless microwave sites.

With the advent of Ethernet, the typical practice is to oversubscribe all the wireless network services (based on individual peak rates) knowing that there is a statistical improbability of hitting the peak rate across all your wireless communication towers at the same exact moment.

Now enter video streaming where data is “streamed” between two wireless communication points over a sustained period (e.g., 30-second YouTube video clips, Skype HD Video Conferencing, Netflix movies). The sustained aspect of these video streams begins to strain the overall stat mux paradigm. Not only does video remain sustained but also it uses large-size IP radio packets that do not vary greatly. VoIP does the same thing, but the effect is much less significant as the overall bandwidth utilization is much lower.

Oversubscription becomes more challenging the more active video streaming is at any given moment. Imagine a scenario where the latest cat-playing-a-piano video gets posted online and everyone starts viewing it at virtually the same time. For a large swath of bandwidth, stat mux will reach zero for approximately four minutes. The upside is that you can add more bandwidth and/or offer differentiated wireless network services levels that guarantee certain bandwidth or application performance. Even so, video streaming does not totally negate the benefits of an Ethernet microwave transport, it just needs to be properly understood and managed to ensure a consistent user experience across all applications and services for your global wireless solutions.

Steve Loebrich
Director of Product and Solutions Marketing
Aviat Networks

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Migrating Utility Networks to Smart Grid with Hybrid Radios

What is the best migration strategy for utility networks migrating to Smart Grid using Hybrid Radios? We look at the technology choices that are available to support legacy TDM and IP-based services and investigate the many demands placed on utility networks. Demands include seamless migration, increased capacity, security, and interoperability.

We believe a hybrid network is the best solution and we explain why in this white paper:

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