For more than two years now, the FCC has been evaluating the necessity and feasibility of opening up the 6 GHz band to unlicensed users of a wide variety of devices. They’ve published multiple notices of their findings, and on April 2, 2020, FCC Chairman Ajit Pai issued a draft version of the official rules, allowing unlicensed operation in the 6 GHz band—over the entire 1,200 MHz spectrum of that band. A final vote on April 23 opened the door to Wi-Fi 6e.
Point-to-point microwaves links are the de facto standard for connecting infrastructure over vast distances quickly and cost-effectively. Lower frequencies, like 6 GHz, allows a network to span long distances with high capacity while maintaining robust availability, especially during rain fade. These characteristics have led to rapid, widespread adoption with more than 40000 links in the 6 GHz frequency band deployed across the US.
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
Figure 1: Aviat Networks’ senior network engineer Ivan Zambrano shares his first microwave radio path plan on the occasion of his 28th anniversary with the company.
Recently, Aviat Networks was privileged to mark a milestone for one of its longest tenured and most distinguished employees, Ivan Zambrano. For 28 years, Ivan has dedicated his professional life to providing education and expert analysis to the microwave backhaul community, on the behalf of Aviat Networks and its corporate predecessors. As a senior engineer, Ivan teaches network transmission courses and other topics around the world on a regular basis.
However, Ivan got his start in the field. In fact, he still has the very first microwave radio path plan he ever created for a television station in Louisiana (Figure 1).
Together with the legendary Dick Laine (Figure 2), the two veteran microwave communications professionals have a combined 97 years of experience in the field. Unbelievably, Ivan actually has seniority over Dick (in the company at least). Dick has only been with us for a mere 26 years!
To help celebrate the occasion, Aviat Networks CEO, president and board member Michael Pangia took some time to personally congratulate Ivan (Figure 3). So here’s to you Ivan! We’re all looking forward to at least another 28 years!
If you’d be interested in having Ivan or Dick lend a hand (or bend an ear) on your microwave project, let us know by dropping a note below. Give us an idea about the type of training or consultation you need and any other pertinent details about the project.
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Southeast USA at night: All these urban areas will need a small cell backhaul solution for LTE at some point. Will it be “fronthaul?” Photo credit: NASA’s Marshall Space Flight Center / Foter.com / CC BY-NC
With the mobile telecommunications space facing an onslaught of data-hungry subscribers and their migration to LTE, operators have embarked on a quest to pack even more service in smaller and smaller service areas. The frontier of these smaller service areas have come to be characterized as small cells. The issue is getting communications into and out of these small service areas. Capacity, coverage and interference all need to be addressed. Some have proposed serving small cells via Centralized Radio Access Networks (C-RAN). To implement a C-RAN, one of the requirements is a newer concept that has come to be termed “fronthaul.”
In a June 2013 meeting of the Telecom Council, Aviat Networks’ chief technology officer, Paul Kennard, took on fronthaul and the challenges it presents for LTE, small cell and C-RAN. In his presentation, he weighed the advantages and obstacles of fronthaul. While the chief advantage of distributing Remote Radio Heads (RRH) around the cell can help alleviate coverage, capacity and interference concerns, it is not easy to reach these RRH locations with fiber in the mostly urban areas where this deployment scenario will be needed most. This is especially true of non-traditional implementation of small cells on light standards, signposts and other non-tower infrastructure collectively known as “street furniture.” Wireless backhaul solutions will continue to be necessary in the grand scheme of things.
More is available on fronthaul in the Telecom Council presentation below as is in an associated webinar.
Photo credit: John “I’m…kind of…fun” L / Foter.com / CC BY-NC
In the United States, the fixed service for wireless communications usually operates in bands licensed either on a link-by-link basis or by block allocation. So why is the 5.8GHz ISM band so important and why should the industry be concerned about current FCC proposals to change the rules of operation in this band.
Many operators use this band because they can install and operate a link in a very short period—much quicker than the usual route of prior coordination and license application that is required in other bands. There are numerous reasons why this approach is attractive, even if it is difficult to guarantee Quality of Service (QoS) in ISM. A common use of this approach sees the operator set up a link in the 5.8GHz band to get the link up and running while in parallel it goes through the coordination process for the same link in the L6GHz band. Then when that license is granted, the operator will move the link to the L6GHz band. This has the advantage that the same antenna may be reused and sometimes the same radio with just a filter change. Another use of the 5.8GHz band for fixed service links is in support of disaster relief efforts where because there is no need for prior coordination that means vital communications links can be up and running very quickly.
Under the current FCC Part 15 rules, equipment can be certified using section 15.247 whereby the above scenarios are attractive to operators as they mimic the conditions that can be found in the L6GHz band. However, the FCC has issued a notice of proposed rulemaking, NPRM, which will change this by requiring a reduction in conducted output power of 1dB for every dB of antenna gain over 23dBi for Part 15.247 point-to-point links. At present, the conducted power at the antenna port in this frequency range is limited to 1 watt, but there is no penalty applied to the conducted power in relation to higher gain antennas on point-to-point links. Should this proposal by finalized then this would reduce the effective range of point-to-point links in this band and would so change the dynamics that the ability to deploy a link in the 5.8GHz band and then “upgrade” to the L6GHz band at a later date would no longer be a feasible option. We would encourage all readers, especially those using the 5.8GHz band to file a comment with the FCC regarding Proceeding 13-49 that this particular change would be detrimental to many fixed link operators, as well as those who rely on this band for fast deployment during disaster recovery.
For more information on this proceeding, email Aole Wilkins at the Office of Engineering and Technology.
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.
Microwaves Could Solve Need for Long-Haul, Low-Latency Networks (via slashdot)
While high-speed optical fiber might be the way to go for large national research networks, point-to-point microwave connections have emerged as key links between financial exchanges. The reason? Ultra-low latency. With widespread interest in sending the timeliest data possible, two separate microwave…
A quick Google-glance around the Internet will reveal a panoply of all-outdoor radios (ODRs) in both microwave and millimeter-wave bands. ODRs do not conform to a universal norm in terms of networking features, power consumption, bandwidth scalability (i.e., capacity) or outright radio horsepower (i.e., system gain).
So if you find yourself asking the questions, “Which ODR is the best fit for my network?” or “How do I narrow the ODR field?” it is good to start with the basics.
The right product choice can be quickly resolved—or at least the candidates can be short-listed—by focusing on three ODR product attributes that most heavily influence the value-for-the-money (i.e., total cost of ownership or TCO) equation:
For many microwave backhaul networks, the growth in underlying traffic is such that products which cannot scale to 500 Mbps/1 Gbps per channel will run out of momentum too early and precipitate the dreaded “forklift upgrade” (also known as the “CFO’s nightmare”).
These same CFOs are also suffering sleepless nights due to rising energy costs—which in some countries can double year-over-year. Therefore, it behooves the operator to seek and prioritize the use of über energy-efficient products, such as the Aviat WTM 3200, which—and this is important—do not compromise on RF performance.
That brings me to my last point: System gain (RF performance) remains a core TCO factor insofar as it can drive smaller antenna usage with the concomitant capex savings. Still, there might be little to differentiate ODRs in terms of RF performance—in which case the spotlight will fall on these other attributes to sway the decision.
Having worked on the operator side and wrestled with TCO analysis on many occasions, my experience tells me that you can narrow your ODR choice quickly by reflecting on these three attributes and the TCO gains they can deliver.
Jarlath Lally
Product Marketing Manager
Aviat Networks