- November 21, 2012
- 70GHz, 80GHz, Carrier Ethernet, E-Band, Frequency, frequency band, Ian Marshall, microwave, Mobile network operator, Radio frequency, Regulation, spectrum efficiency, Wireless Backhaul
Because of need for higher capacities, the trend toward shorter link distances for mobile backhaul and declining product costs, 70/80GHz (i.e., E-band) solutions are gathering significant interest for mobile backhaul and enterprise access applications. However, because these frequencies are new to most people, there is little understanding of costs and other issues related to licensing the 70-80GHz spectrum.
- November 16, 2012
- all-outdoor, Ethernet, Gigabit Ethernet, microwave, Microwave Radio, microwave radios, Microwave transmission, Radio, radio modem, radio sector, split-mount, technology, Telecommunications
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.
Product Marketing Manager
If you look in the November issue of MissionCritical Communications, you will see an article by Aviat Networks director of marketing and communications, Gary Croke. In his article “Know Your Microwave Backhaul Options,” Gary covers:
- Benefits of using indoor, outdoor and split-mount microwave radios in various scenarios
- Rationale for choosing microwave over fiber (especially for LTE)
- Deployability of microwave
- Software-upgradeable capacity for “pay-as-you-grow” capex scalability
- Cost contribution of towers over the first 10 years of LTE implementation
- And more
You can read Gary’s article (on page-30) here—MissionCritical Communications—November 2012.
The two main vibration types for light poles are shown in this figure. Both of these two vibration types will create sway that might affect the link performance for small cell microwave backhaul.
There is real concern from operators that utility, streetlight and traffic poles are not designed to meet the minimum twist and sway standards for deploying microwave solutions for small cell backhaul. Our research suggests that not all poles are created equal, however. Under certain circumstances these structures can be an option for deploying microwave backhaul for small cells.
Twist and sway requirements for towers and poles that support microwave backhaul hops are more stringent than for other RF equipment. This is especially true for deployments in frequency bands above 18 GHz where the antenna beamwidth is narrower than below 18 GHz. Standards such as the TIA-222-G set a minimum twist and sway that a structure should be able to endure for hosting a microwave installation. This creates concerns for operators interested in deploying microwave for small cell backhaul on structures including utility, streetlight and traffic poles that are not designed to meet this standard. Although the use of a sturdy structure is always recommended a close look at utility, streetlight and traffic poles suggests that under certain circumstances these structures can be an option for deploying microwave backhaul for small cell.
The installation of any equipment on existing poles—including small cell and backhaul radios and antennas—will necessarily change the weight and wind loading characteristics of the deployment pole. This will require a structural analysis to verify if the existing pole still meets the standards or the commercial criteria set by the pole manufacturer. For more information on Aviat’s analysis of pole sway for small cell backhaul see our PDF.
Marketing Engineering Specialist
- October 5, 2012
- annex c, Commission for Communications Regulation, ComReg, Frequency, Ireland, links services, microwave, microwave spectrum, point-to-point, spectrum rules, telecom regulator
Spectrum (Photo credit: Free Press Pics)
In response to the ever-growing demand for spectrum to satisfy the increase in usage of data hungry mobile applications and in line with recently published ECC recommendations, ComReg (i.e., Ireland’s telecom regulator) issued a consultation document looking at the future demands on spectrum for point-to-point fixed links. September saw the publication of the conclusions and subsequent decisions arising from that consultation, to which Aviat Networks was the only manufacturer to respond. This blog highlights some of those decisions:
One of the major topics was the requirement for more spectrum allocated for point-to-point usage. Consequently, ComReg has made the following announcements:
- ComReg intends to open the frequency bands below, as there is a significant demand for fixed links services in the 28 GHz, 31 GHz and 40 GHz band:
- The 32 GHz band may be made available for fixed links services at a later stage subject to its potential for future PP/PMP use and the demand on spectrum for PP use in the 31 GHz (31.0 – 31.3 GHz paired with 31.5 – 31.8 GHz) band
- Within the 28 GHz band, as per REC T/R 13-02 Annex C, the following frequency ranges will be made available for fixed links services: 27.9405 – 28.4445 GHz and 28.9485 – 29.4525 GHz
- Frequency bands 28 (27.5 – 29.5) GHz, 31 (31.0 – 31.3 paired with 31.5 – 31.8) GHz, 32 (31.8 – 33.4) GHz and 40 (40.5 – 43.5) GHz will not be opened for PMP use in the current spectrum strategy period 2011 – 2013
Aviat Networks supported this initiative during the consultation process and is pleased to see ComReg make these announcements as a move to satisfy the increasing demand for microwave spectrum. Specifically, frequencies in the range of 28 to 42 GHz are ideal for short-haul urban links, and we expect the decision by ComReg to stimulate further growth of microwave for fixed line and mobile network applications.
- High-Low search radii for the 23 GHz and 26 GHz bands will be reduced from 200 meters to 100 meters. The consensus of current licensees operating within the 23 GHz and 26 GHz bands is that the reduced radius will improve spectrum planning and reuse, which will improve spectral efficiency
- There will be no distinction between rural and urban areas concerning the High-Low search radius
- Antenna size will be limited to 0.6 meters in the 23 GHz and 26 GHz bands
- ComReg will allow use of 56 MHz channels in the 26 GHz band only where the licensee has a National Block license containing contiguous blocks of spectrum
- ComReg will permit the use of higher bandwidths, as shown in the table below, to facilitate the increase in mobile data demand:
ComReg signalled its intention to potentially reopen the 26 GHz block license scheme for a further round of National Block assignments, subject to market demand. In the past, Aviat Networks commented that it believes block licensing is not the most appropriate method of licensing in the microwave bands. However, ComReg disagrees with that view.
The combined expansion in spectrum use—new bands and larger channel allocations—underlines the popularity and ongoing viability of microwave as an alternative to fiber in urban networks experiencing rapid traffic growth and geographic expansion.
Aviat Networks welcomes the ComReg announcement. We already address all the band/channel assignments made by ComReg.
Aviat WTM 6000 trunking microwave radio
Back in the day, trunking microwave radios were huge power-hungry beasts that consumed vast quantities of power and space at equal rates. They were complex “animals” that took days to install and hours to configure. Then they had to be looked after like well-loved but aged members of the family—with care, all due respect and consideration. Over time, components went out of adjustment and had to be brought back into line through various tuning routines, but overall they did their job as the super-reliable backbone of the POTS (i.e., Plain Old Telephone Service).
Jump forward a few decades and the latest trunking microwave solutions are elegant and graceful—almost svelte. With their current high levels of electronic integration, a complete repeater system can stand in a single rack space—unheard of until the most recent products. Furthermore, these new systems consume dramatically less power—a typical 3+1 system (i.e., four transceivers) consumes less than 400 watts. So now, backbone operators can save significantly on operating expenditure because of decreased space and power requirements at their microwave radio shelters.
Evolving microwave systems from analog to digital microwave systems carrying digital payloads was a rocky and dangerous path. The next migration from TDM payloads to IP payloads appears to be just as treacherous. How can a traditional TDM backbone radio, typically configured with N+1 radio protection switching, be reconfigured to transport a non-TDM payload that does not suit N+1 switching? IP transport is a completely different environment altogether! Luckily, trunking radio system designers have not ignored the Internet revolution and are perfectly aware of these challenges. In fact, well-appointed trunking microwave radio systems allow a graceful evolution from TDM to IP, with capability to transport both types of traffic simultaneously—and with their own ultra-reliable protection schemes!
Today, trunking microwave radios can support both TDM and IP seamlessly, offer robust radio performance and highly reliable switching and really do make it easy for operators to design mission-critical backbone networks. They offer mean time between failure (MTBF) reliability figures into the hundreds-of-years and highly integrated yet modular designs, which make expansion very straightforward. Before deciding on a trunking microwave radio, consider if the system:
- Allows easy migration from TDM to IP with a minimal amount of replacement materials
- Can expand to an expected maximum channel capacity (for example, six channels) without needing additional racks, etc.
- Enables repeater configurations within one rack
- Has a field-proven heritage of reliability and performance
Senior Product Manager
- September 18, 2012
- Antenna diversity, Antennas, China Basin, Dick Laine, horn antenna, microwave, microwave propagation, Principal Engineer, Radio Head Technology Series, Radio Heads, Radiohead, San Francisco, Space Diversity
Horn antennas on the roof of a microwave relay station near Madison St. and 17th Ave, Capitol Hill, Seattle, Washington state, USA. (Photo credit: Vladimir Menkov via Wikipedia)
Between any two microwave radio antennas, there is one direct ray and multiple refractive/ reflective multi-path rays. In the eighth and last installment of our Radio Head Technology Series, Aviat Networks Principal Engineer and master storyteller, Dick Laine, relates how restrictive tower rules for San Francisco’s historic China Basin Building required fine adjustments of a horn antenna to resolve reflective rays from the surrounding bay.
As Dick tells it, to accommodate a Space Diversity arrangement, one horn antenna on the building had to be hung upside down. During the installation process, the alignment for the upside-down diversity antenna created a reflection point 3 miles out into the bay. The performance was horrible, but at the time, no one knew why. So when a little speedboat or anything larger went through the reflection point, there would be an outage as the signal was interrupted. There did not seem to be an obvious fix to the alignment issue. The horn antenna did not have a way to check the alignment on the horizontal with a bubble level.
To find out how Dick solved this antenna mystery, register for the Radio Head series (it’s free). Then to put it all in context, Dick goes over Huygens’ Principle as it applies to microwave signal diffraction. And if you ever wondered what happened to periscope antennas, Dick provides some key insight! Tune in to find out!
- August 14, 2012
- Constellation, Dick Laine, Diversity scheme, Eclipse, line-of-sight, LOS, MegaStar, microwave, Microwave transmission, Radio frequency, TR6500, WTM600
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!
Scale of MIMP’s mobile microwave radio infrastructure can be gauged by observing the installer at the very top of the 25-meter radio mast.
In the past, we have seen microwave radio installations at zoos, auto races, and on mountaintops reached by funicular and other one-of-a-kind implementations. This time, one of our partners, MIMP Connecting Solutions of South Australia, is in the process of completing an installation that is at the same time completely novel and tremendously important in the struggle to preserve indigenous cultures.
Currently, MIMP is rolling out microwave backhaul for the Australia Pacific LNG (APLNG) liquefied natural gas joint venture in Queensland, Australia. However, in Queensland, and other parts of Australia, legislation in recent years such as the Aboriginal Cultural Heritage Act 2003 has sought to preserve culturally significant Aboriginal places from development. This impacts the installation of the APLNG microwave backhaul network because conventional radio sites cannot be constructed under the auspices of this legislation on protected Aboriginal land.