In February, Aviat announced the availability of its transport products that conform to the Telecom Infra Project (TIP) Wireless Backhaul Project Group specification. Aviat’s products include a modular architecture that allows for an integrated multi-band (E-Band + Microwave) solution with open netconf/yang interfaces. The TIP Wireless Backhaul specification was developed by the Wireless Backhaul Project Group within TIP in collaboration with the world’s premier mobile operators, including Axiata, Deutsche Telekom, Telefonica, TIM Brazil, and MTN.
Artificial Intelligence. Photo credit: miuenski / Foter / CC BY-NC-SA
Once upon a time, cell sites served as little more than passive pass-throughs for phone calls and text messages. Because voice calls and SMS posts did not require much wireless capacity cell sites did not require very robust provisioning. Now that the Internet has gone fully mobile with streaming videos and real-time applications such as VoLTE and IPTV regularly crushing network capacity design parameters, the time to get smart about backhaul and access traffic has arrived. The time for Layer 3 intelligence is now.
In fact, for some time mobile cell sites have transitioned from simple Layer 2 connected sites for 1990s-style mobile phone and data access to multipurpose centers for delivering new, smart device services. However, they can only provide new, smart services if they are built upon Layer 3 technology that offers intelligent handling of wireless traffic. Only IP routing technology is capable of such functionality.
But here comes the catch regarding IP routers providing Layer 3 intelligence at the cell site. With more than 50 percent of the wireless traffic in the world going to and coming from mobile sites through backhaul radio, Layer 3 intelligence must have awareness of microwave networking. And regular routers just do not offer microwave awareness. A new class of device must fill the void left by regular routers that frankly do not have enough “smarts” to deliver Layer 3 intelligence for cell sites that depend on microwave backhaul. A device that combines the best attributes of microwave radios and IP routers.
To provide a closer examination of this issue, Aviat Networks has authored a new white paper—no registration required—that makes the case for Layer 3 intelligence at the cell site. And how to implement a new class of “smart” devices that enable microwave radio awareness with IP routing.
On Dec. 16 2013, Ofcom—the UK telecom regulator—announced a new approach for the use of E-band wireless communications in the United Kingdom. This new approach results from an earlier Ofcom consultation exercise in which Aviat Networks participated.
Small cell will enable mobile usage in dense urban environments but will need a backhaul solution to make it possible. Photo credit: Ed Yourdon / Foter / CC BY-SA
The Case for Small Cell Backhaul
As the search for frequency bands with suitable capacity for small-cell backhaul continues, frequency bands above 50GHz start to appear attractive because they offer both high-bandwidth availability and short range owing to their inherent propagation characteristics. The white paper available at the bottom of this blog examines spectrum in the 57-64GHz range to see whether it can be of use for small cell backhaul.
In many countries, the frequency range 57-66GHz is split into a number of discrete bands with differing requirements and conditions of use and/or licensing. These differences will be highlighted where applicable.
From a global point of view, the use of this spectrum by Fixed Services (FS) is being addressed by the ITU-R in its draft report on Fixed Service use trends in WP5C, which is currently under development and states:
57 GHz to 64 GHz
The radio-frequency channel and block arrangements of these bands for FS are defined in Recommendation ITU-R F.1497.
In 2011, around 700 links were in use in this band in a few administrations. The majority of the links are used for fixed and mobile infrastructure.
The air absorption around 60 GHz is over 10 dB/km. This condition restricts the hop length; on the other hand, the spectrum reuse efficiency is high. This feature makes the band suitable for small cell mobile backhaul.
Clearly, a global reported usage of 700 links would suggest a great deal of underutilization, although with unlicensed use in many countries it is difficult to know whether these figures are accurate or not. Regardless, there are reasons as to why this could be the case, while noting that the ITU-R believes this band has potential for small cell backhaul.
One factor is that this spectrum is not allocated solely to the Fixed Service. In fact, in many countries the Fixed Services have no access to this spectrum at all. A more detailed country-by-country breakdown follows. Please sign up below to receive the entire white paper.
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Ian Marshall
Regulatory Manager
Aviat Networks
In a recent interview, Trevor Burchell, Aviat Networks VP for Middle East, Africa and Europe sales and services, commented on the recent trend of low latency microwave networks. Though increasingly found in the telecom infrastructure of financial institutions, low latency microwave is not limited to these applications, he says. Burchell sees its applicability in uses as diverse as health care, government and utilities.
Some considerations are common to all microwave networks—low latency and all others, according to Burchell. Proper path planning and network engineering must be executed in order to have the most fully functional wireless point-to-point backhaul possible, he says.
In general, Burchell sees microwave as the best choice where telecommunications have to be rolled out quickly and cost effectively. There are many other points to consider. The complete interview is available online in Engineering News.
IWCE 2013 (International Wireless Communications Expo), March 13-14, was a tale of two different but related stories. The first was the continuing enhancement of legacy P25 voice-centric products/features/ applications and the second was discussion of the LTE broadband data-centric network plan/products/ solutions of the future.
P25 continues to be the only source of mission-critical voice, and the consensus is that will not change for maybe 10 more years—or longer. We saw really cool product enhancements from Motorola and Harris. Clearly, there is plenty of investment continuing in P25, and vendors believe they will get a return on that investment. There is still a tremendous amount of work to be done on going from analog to digital systems and wideband to narrowband.
In contrast, LTE broadband will probably take another 1.5 years just to get to the stage of RFQs. However, we did see a lot of innovative technology and interoperability demonstrations. Who would have thought that Harris handheld radios would be located in the Alcatel-Lucent booth and Motorola in the Raytheon booth?
There were many talks on FirstNet strategy and planning. Chief Dowd said FirstNet would announce a general manager within a couple weeks…let’s hope it is a public safety professional with many years of experience in setting up mission-critical networks. Of course, the industry pundits were there to discuss their view of this enormous challenge…unfortunately it appears the thinking is still very divergent…which can only mean that someone is going to be disappointed by the decisions FirstNet will make.
Many provider-based discussions were also held. For example, Aviat’s own Gary Croke gave a presentation on the considerations that any organization must make for high-speed backhaul and how microwave fits into those.
Lastly, we heard some excellent talks on engineering this network. Skilled network designers like Bob Shapiro gave us some insight into how the LTE network will look different from P25 networks (e.g., number of basestations, capacity of traffic, complexity of design). Good news is the industry is developing some excellent design tools to aid in designing the network.
The signs are positive for the public safety industry. IWCE show attendance was good, vendors showed up with real innovation and investment in new products, the Public Safety Broadband Network continues to move ahead…cannot wait for APCO in the fall!
Randy Jenkins
Director Business Development
Aviat Networks
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:
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.
For discussion purposes of ultra low latency, two theoretical ultra low latency microwave networks are compared to an existing optical Chicago-NY network.
In today’s ultra-competitive High Frequency Trading markets, speed is everything, and recently wireless technologies, and specifically microwave networking, have been recognized as a faster alternative to optical transport for ultra-low latency financial applications.
Even though microwave technology has been in use in telecommunications networks around the world for more than 50 years, new developments have optimized microwave products to drive down the latency performance to the point that microwave can significantly outperform fiber over long routes, for example between Chicago and New York. This has provided a new market opportunity for innovative service providers to venture into the microwave low latency business.
Although reducing the latency of the equipment is an important consideration, the most important metric is the end-to-end latency. Many factors that influence overall end-to-end latency require a deep understanding of the technology and how this is applied in practice.
This white paper will show that to achieve the lowest end-to-end latency with the highest possible reliability and network stability not only requires a microwave platform that supports cutting edge low latency performance but also a combination of experience and expertise necessary to design, deploy, support and operate a microwave transmission network.
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!
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.
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
Five-nines (99.999 percent) availability is a concept that is familiar in wireless engineering. Dick Laine, principal engineer of Aviat Networks, compares five-nines availability to 78-rpm records in our most recent episode of the Radio Head Technology Series.
As he relates, even with scratches and pops, a 78-rpm record still is able to transfer aural information so that you can hear it, i.e., its availability is intact, as it does not drop performance. Scratches and pops only represent degradation in the quality of communication. But when the record is broken, an outage occurs—no record, no communication.
The same goes for wireless communication systems. If a microwave link drops 315 or fewer seconds of microwave communications per year (in increments of up to 10 seconds at a time), it is maintaining five-nines availability. The microwave link is offering 99.999 percent availability for wireless backhaul. Only if the microwave link is unavailable for more than 10 seconds has an outage occurred, for the purposes of determining if microwave communications traffic has been dropped.
Dick goes on to explain about what happened in 1949 when 78-rpm records were superseded by 45-rpm records. Dick got a sneak peek at the top-secret 45-rpm record project when he visited the legendary RCA facility in Camden, New Jersey, which played a crucial role in the development of the modern music, radio and television businesses. Unfortunately, unlike a five-nines microwave link, 78-rpm and 45-rpm records are mostly unavailable nowadays.