With the goal of a hyper-meshed 5G street level network, clearly today’s small cell deployments represent just an interim phase in a progressive network densification—pushing the network outward. This means today’s small cell sites will become tomorrow’s macrocells, or hub sites.
Future-looking mobile operators have planned for this eventuality. In the developed world, small cell and the Internet of Things (IoT) drive mobile network densification. However, in the developing world the primary goal of enterprise connectivity spurs network densification, due to lack of wireline infrastructure to business buildings. The end result of network densification is the same.
- February 21, 2014
- 70GHz, 80GHz, backhaul, densification, E-Band, microwave communications, microwave congestion, millimeterwave, small cell, small cell backhaul, small cells, urban backhaul, urbanized backhaul
As the telecom community searches for reasons why Small Cell architectures have not yet launched en masse, “experts” are quick to suggest that lack of backhaul technology as the key perpetrator.
As I wrote in a 2013 article, starting with wireless microwave communications (6-42GHz frequency range), solutions for backhaul both large and small are available and effective today for mobile operators.
This is the second in a series that highlights technology available to enable immediate deployment of small cell backhaul. This segment focuses on the convenience of using wireless E-band as a complement to microwave for small cell backhaul, while bringing to light some of the true obstacles to small cell adoption.
E-band is a part of the electromagnetic frequency spectrum in the millimeter range between 71-76 GHz and 81-86 GHz. In recent years, there has been more interest in this frequency band, because traditional microwave (6-40 GHz) bands are now very congested in parts of the world, and that with the densification of mobile networks due to the introduction of 3G/HSPA and 4G/LTE, link distances between cell sites are shrinking in urban areas.
The surge in interest in a new network of outdoor small cells is driving a new approach toward cost-effective wireless solutions for backhaul. E-band offers a large swath of available spectrum with more than 10 GHz at stake—it represents more bandwidth than all the combined open frequency bands below 40 GHz.
What is needed is an all-outdoor, packet millimeterwave radio, offering a rich set of features, expressly built to support mobile (macro and small) backhaul by:
- Conforming to planning and local authority “community-friendly” aesthetics and design approval guidelines
- Eliminating external parabolic antennas, thus enabling significant savings on shipping, storage and handling costs
- Weighing dramatically less than competing solutions, resulting in easier handling and installation within 30 minutes
- Consuming less power, allowing flexibility in electrical source options such as via fixed supplies or Power over Ethernet (PoE), with built-in surge protection
As the world becomes increasingly urbanized—for the first time ever, more than 50 percent of the world’s population lives in dense urban areas—it is also the place where we communicate the most and networks are most stressed to keep up. Small cell designs offer a convenient method to densify networks.
However, my prediction is that in the near to medium term, deployments will be surgical—to plug gaps where coverage is poor and to fill hot-spots where incremental capacity is needed. It is important to note that outdoor, public access small cells will coexist and in some ways compete with other densification solutions, including DAS, wi-fi, and additional macro cell builds. Small cells may indeed need to be backhauled from light poles and building sides, but ultimately they need to go where they need to go, while serving the primary goal of not-spot and hot-spot filler.
The more pressing obstacles for outdoor small cells include the method operators use to assess the business case and solve the construction and site acquisition challenges borne by the paradigm shift. The expectation is that the ecosystem will produce a solution that makes small cells easier and cheaper to deploy than macro cells. The problem with that thinking is the economics of it all. The business case will continue to struggle to prove out vs. macro cell, as scalability and network dimensioning quickly come at odds with requirements for unbridled capacity, high reliability and network intelligence.
Operators think they may be vying for a diminutive device supporting multi-generational, multi-band, multi-media and multi-OSI-layers, but that utopian requirement breeds complex challenges in permitting, site acquisition, interference, costs, and so on—all items recently in the pick-list of a flash poll by Light Reading. I maintain that we are not just over-thinking, but over-expecting the benefits of a pure-play small cell rollout. We might all be better off following the “K-I-S-S” principle for the foreseeable future, which might produce this guidance:
- Use small cells only where it makes sense
- Deploy it with tried and true technology (i.e., wireless microwave)
- Consider E-band for expansion in dense urban outdoor environments
- Be mindful about keeping your budget in the black, but don’t stress about challenges that need not manifest in your business
So here’s to Keeping it Small and Simple!
Senior Manager of Marketing
- October 8, 2013
- Aviat Networks, backhaul, frequency bands, Ian Marshall, microwave, Radio spectrum, small cell, Spectrum, Telecommunications, White Paper, wireless
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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Microwave backhaul is being reassessed as a strategy for small cell LTE traffic aggregation on business campuses. Photo credit: cbmd / Foter.com / CC BY-NC-ND
Small cells get all the press! As LTE rolls out in networks on every continent except Antarctica, small cells are grabbing headlines in technology trades and geek fan-boy blogs across the Internet. They’ll be needed sooner or later to provide LTE access in all those places around corners of buildings on business campuses, in urban parks surrounded by concrete canyons and other inaccessible locations. But little or only passing thought is paid to the ways in which small cell traffic will be aggregated back to the main network.
However, in a new FierceWireless ebook, microwave backhaul is pointed out as one of the critical strategies to provide throughput for all the small cell traffic to come. Microwave was here before small cell. And it’s such a good fit for small cell, if it had not already existed, we’d have to invent it now! Our director of product marketing, Stuart Little, tells FierceWireless that microwave meets the capacity needs of LTE backhaul. And Fierce adds modern microwave technology is changing the perceptions of its use for small cell backhaul.
Neither sleet nor rain nor changing K factors at night will stop microwave from small cell service. Specifically, Little tells Fierce that rain has little to no effect on microwave at the lower frequencies, and where it does have some effect in the higher bands, different technical techniques can help mitigate it. To find out more about small cell microwave backhaul, we recommend any of the Aviat blogs and related articles below. Or just read the FierceWireless ebook.
- June 26, 2013
- Chief technology officer, CRAN, grand scheme of things, LTE, Radio Access Network, radio access networks, Remote radio head, small cell, Telecommunications, traditional implementation
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.
- May 24, 2013
- backhaul, Cellular network, CRAN, CTIA, DAS, Distributed antenna system, FirstNet, LTE, public safety, small cell
CTIA: The Wireless Association held its annual show in Las Vegas, May 21-23. Photo credit: @jbtaylor / Foter.com / CC BY
This week, Aviat Networks participated in the very well attended CTIA 2013 wireless and mobile trade show in Las Vegas. The theme for this year’s event was “THE Mobile Marketplace” with various areas of focus dealing with applications, devices and, of course, infrastructure. LTE, backhaul and small cells were once again important infrastructure-related topics during the event.
Aviat was a Platinum Sponsor of the Tower & Small Cell Summit—a sub-conference program composed of presentations, panels and case studies on wireless backhaul, mobile video, Distributed Antenna Systems (DAS), small cells, 4G and residential tower builds. I spoke on a panel at this event and shared our views on small cell evolution, including our thoughts on the migration of the mobile network to the Cloud Radio Access Network (C-RAN) architecture—if interested in this topic, please register for our upcoming webinars: North America or Europe, Middle East, Africa.
In addition, this show also paid significant attention to FirstNet—the nationwide public safety LTE network here in the United States. Aviat’s Ronil Prasad shared Aviat’s perspective on FirstNet, options for network sharing to reduce costs and best practices for building mission-critical backhaul networks for public safety LTE (with our 60-year history in public safety and our deployments in some of the largest LTE networks in the world, we are uniquely qualified to talk on this topic).
In addition, Aviat’s meeting facility experienced a constant flow of customers, industry analysts and partners, which kept Aviat staff on its toes for the entire event. Overall, it was a great show and Aviat was happy to participate to share our views on some of the most exciting new topics in mobile networks in the U.S.
Director, Marketing and Communications
Mobile backhaul has become one of hottest and most contentious subjects in telecommunications ever since LTE cellular phone technology started to ramp up. One much overlooked aspect of deploying LTE lies not in the capacity required to backhaul cell site traffic but the effort required to build out the required sites. It is really about site surveys, frequency coordination, engineering, planning and installation. Aviat Networks’ chief technology officer (CTO), Paul Kennard, addressed this dichotomy and others related to LTE in his presentation to the IEEE’s Communications Society.
Although, Paul did have plenty to present regarding capacity. For example, with proper use of rings, overbooking, QoS, XPIC and other techniques and technologies, microwave backhaul can provide 400 Mbps-plus throughput. Compare this to the realistic throughput demands of a typical LTE site that max out at about 100 Mbps.
He also delved into the emerging backhaul category for Small Cells—designed to supplement traditional cellular infrastructure. The fact is that traditional techniques of deploying cellular macrocell basestations will be insufficient to provide broad enough coverage for this LTE wireless technology. To augment macrocell coverage for LTE mobile telecommunications providers have been investigating, trialing and, in some cases, deploying one or more of several small cell technologies (e.g., picocell, microcell, femtocell). Consequently, new methods will be needed to backhaul traffic from Small Cell sites.
Fiber backhaul may not be available at all small cell sites and when it is it could be very expensive to trench long distances. Regular line-of-sight (LOS) microwave with its parabolic dishes could prove aesthetically unsuitable for many Small Cell locations and/or difficult to install. Non-line-of-sight (NLOS) microwave and millimeter-wave point-to-point and point-to-multi-point wireless may have their applications, but their latency of 5-10 ms may be too much for real-time applications and voice—not to mention licensed spectrum is costly and unlicensed spectrum is very risky due to interference issues.
Spectrum above 6 GHz is much more available for small cell backhaul than spectrum below 6 GHz.
A different solution to handle the burgeoning demand for mobile broadband capacity will be needed. More spectrum coupled with more spectral efficiency will not be sufficient. A clear solution is more sites, but deploying more macro-sites in urban and dense urban areas (where most of the traffic will be needed) will not be feasible.
Small cells promise a new “underlay” of outdoor and indoor, low power micro-cells that are deployed on public and private infrastructure within the urban clutter, are seen as seen as a likely solution. Sites being considered include:
- Pole tops (e.g., such as street lighting, traffic light systems, electric utility poles, telco poles)
- Bus stops
- Building walls
- Building rooftops
These new sites will need to be compact, simple to install, energy efficient and incorporate an organically scalable and tightly integrated backhaul solution. As a result, there will be many more sites—some projections estimate that up to 10 small cells will be deployed for every macro-site. Small cells hold out the promise of great gains for the end users but massive challenges for the operators.
Small cell deployments so far have mainly been concentrated in Europe (3G) and the USA (LTE). 3G small cells may also be deployed in other regions as a means to avoid the difficulties in obtaining planning approval for larger macro-cell sites.
It’s Still Early
Today, as far as wireless small cell backhaul (SCBH) solutions are concerned, there is evidence of product immaturity and hyperactivity in equal measure.
There is profusion of aggressively hyped solutions, including many that are a rehashing existing/niche solutions and at the opposite extreme some very new and unproven technologies. In practice, these solutions are jockeying for position while operators grapple to understand the formidable planning and infrastructure challenges being thrown up by their small cell ambitions. It is apparent that few appear that they will fully satisfy the anticipated and emerging requirements in terms of performance (i.e., capacity, latency, availability), size/shape, ease of deployment and most importantly, total cost of ownership. For the complete article, download the PDF.
Stuart D. Little
Director, Product Marketing
- November 2, 2012
- 4G, backhaul, Business Development, Carrier Class, Chicago, Lake Michigan, Mobile network operator, mobile operators, OPEX, pole climbs, small cell
In Chicago, the waves on Lake Michigan were nearly as big as the controversy surrounding the topic of small cell backhaul at the 4G World show it hosted. (Photo credit: Pedco via Wikipedia)
4G World struggled a bit due to Hurricane Sandy, but went on as planned. Unfortunately, some speakers and attendees were not able to get to Chicago due to travel cancellations. I have to admit that watching surfers ride the big waves on Lake Michigan was an added bonus for the week!
Back at the show, small cell was the focus and backhaul was its No. 1 topic. Everyone has heard the concerns over technologies, costs, etc. The soapbox was available for anyone to jump on and espouse the potential benefits of their products. I believe that companies are selling their product capabilities, not addressing mobile operators’ real needs. Why? The biggest issue is that mobile operators, in most cases, really do not know what they need. The complexities of implementation are so diverse in small cell, that it is taking operators a long time to draw conclusions about their best path forward. Enter the fog of vendor technology pitches!
I believe that the real issues to be resolved center around implementation and OPEX control not technology. A few technologies could help, but they are not ready to provide the Carrier Class performance that the operators need. They will only have marginal effect on the final solution, in any event. What we need are answers to questions such as:
- Who can climb which poles in the city and to what heights?
- What are the power restrictions and cost of power on these poles?
- What size enclosure is allowed to be on the poles and on the ground?
- What are the aesthetic requirements for such an enclosure?
- What attachment height is needed to architect the best network for both access and backhaul?
Most people think fiber is a slamdunk—that is not the case. You need to read the fine print and ask:
- How plentiful are existing fiber onramps in the metro core area?
- What’s the cost of putting a new onramp in place and stringing fiber from below street level up poles to small cells?
- What piece of the action are municipalities going to demand for all this new telecom construction?
My recommendation: keep an eye on the technology evolution but focus on the real issues at hand. Partnerships with companies that have proven skills will be critical as these problems are best handled by a team of diverse thinkers. Look for ones that have a history in the business and have demonstrated innovation in all its facets. They are the partners who will get you through these very difficult problems.
Director Business Development
- October 19, 2012
- 4G, Chicago, LTE, milimeter wave, NLOS, non-line-of-sight, Non-line-of-sight propagation, PMP, point-to-multipoint, Point-to-multipoint communication, point-to-point, ptp, small cell, unlicensed spectrum
The 4G World show is in 10 days in Chicago, Ill. Speaking of 4G, those of us at Aviat Networks are excited to see what LTE technology will be on display and its promise of 4G speeds for our mobile networks. Confusion will mount as vendors address the myriad capabilities of LTE and the challenges of implementing such an amazing network. Small cell access will be a key topic. Mobile operators need these outdoor-mounted, street-level smaller versions of their LTE basestations to offload some of the overwhelming demand for capacity in metro areas.
One of the critical small cell challenges is backhaul. Imagine the complexity of aggregating traffic from the numerous small cells deployed at key intersections in a big city. Fiber cannot be everywhere and is not economical to operate in most metro locations. There is a lot of buzz around unlicensed Non-Line-of-Sight (NLOS) Point-to-Multipoint (PMP) radios that take advantage of fewer installations than traditional Point-to-Point (PTP) microwave. But be careful of comparisons between PMP and PTP microwave…we hear a lot of hype, promulgated by confusion and relying on fear!
Unlicensed spectrum sounds good but suffers from serious interference issues. NLOS radio capacity drops significantly when trying to transmit around a building. You have to ask: Is the resultant capacity sufficient to serve this specific small cell backhaul need? There are also concerns over latency because LTE has strict delay requirements, and Voice over LTE (VoLTE) will really struggle if latency is not within specification. What about spectrum…is it actually available? Is there only 20 MHz of spectrum available when 40 MHz of capacity is needed?
What about good ol’ reliable and proven Line of Sight (LOS) PTP microwave? With the emergence of millimeter wave PTP radios, capacities up to 1Gbps can be achieved easily over 1-2 kilometers—certainly sufficient for metro small cell distances!
If you have a chance to attend the show, please take the time to ask some of these questions…or else you may be victimized by hype, confusion or fear.
If you would like to hear straight talk on this topic, tune into Aviat’s Small Cell Backhaul webinar. Stay tuned for future blog posts to read about spectrum, capacity, latency, FCC rule changes and technology evolution as the search for viable solutions to the small cell backhaul challenge continues!
Director Business Development