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.
To summarize, the new approach, which is available for licensing after Dec. 17, 2013, splits the band into two segments. Ofcom will coordinate the lower segment of 2GHz, while the upper segment of 2.5GHz will remain self-coordinated as per the prior policy.
The segment Ofcom coordinates will follow the usual regulatory processes for all the other fixed link bands it oversees. Moreover, Ofcom has already updated all the relevant documents and forms to accommodate E-band. While we (i.e., Aviat Networks, other telecom vendors) would have preferred the larger portion of spectrum to have been granted to the Ofcom-coordinated process, we welcome this new arrangement because it provides an option for greater security and peace of mind to operators in terms of protection from interference than was envisaged for the previous all self-coordinated spectrum regime.
For a more detailed look at the new E-band arrangement, Figure 1 shows the Ofcom-coordinated section sitting in the lower half of both the 71-76GHz and 81-86GHz bands thus allowing for the deployment of FDD systems in line with ECC/REC(05)07.
In terms of channelization within the Ofcom-coordinated block, the regulator announced that it would permit 8 x 250MHz channels, 4 x 500MHz channels, 1 x 750MHz channel and 1 x 1000MHz channel as per ECC/REC(05)07. Ofcom also stated that 62.5MHz and 125MHz channels will be implemented as soon as the relevant technical standards, etc., from ETSI are published. Figure 2 shows the Ofcom channel plan:
Regarding equipment requirements, Ofcom stated that it will allow equipment that meets the appropriate sections of EN 302 217-2-2 and EN 302 217-4-2. This includes the antenna classes (e.g., classes 2-4) that will allow the deployment of solutions with flat panel antennas. Aviat Networks welcomes this approach and hopes that other regulators—notably the FCC in terms of antenna requirements—currently considering opening up and/or revising their rules for E-band adopt similar approaches.
The license fees for the self-coordinated segment remains at £50 per link per annum, whereas in the Ofcom-coordinated segment the fees are bandwidth based as reflected in Figure 3:
Notwithstanding the current fees consultation process that Ofcom is undertaking, these “interim fees” will remain in place for five years, after which time the results of the fees review may mean that they will be amended.
Also because of responses received during the consultation process, within the self-coordinated block, Ofcom will now require the following additional information for the self-coordination database: antenna polarization (horizontal, vertical or dual), ETSI Spectrum Efficiency Class and whether the link is TDD or FDD.
A growing telecommunications trend in South Africa and other emerging markets across the African continent is the move to cell tower sharing. There are many reasons for this, but the need to reduce capital expenditure (capex) on towers and other infrastructure and retarget spending toward network development, customer acquisition and retention and need to accommodate growing mobile data traffic levels have forced the issue.
The trend toward independent ownership of telecommunications infrastructure such as tower sites, with leasing arrangements for multiple operators on each tower, closely mirrors moves in mature telecommunications markets around the globe, including the U.S. and Europe, as well as other big emerging markets such as India and the Middle East.
Tower sharing prevalent
While there is some reluctance by industry incumbents to offload tower infrastructure because they fear losing market share and network coverage, the tower-sharing model is still becoming more prevalent. This is particularly evident in markets where there are new players trying to penetrate the market, as well as in countries where coverage in rural, sparsely populated areas is needed to drive growth. Other important factors, such as the rising cost of power in South Africa, or unreliable power delivery in other parts of the continent have also helped to drive this trend.
Thus, the adoption of this model has gained significant momentum in Africa since 2008, with major mobile operators in Ghana, South Africa, Tanzania and Uganda striking deals to offload existing infrastructure to independent companies. These independent “tower operators” handle the operation and management of these towers, leasing space back on the towers to multiple network operators. This helps to reduce operating costs, improve efficiency and potentially boost an operator’s network coverage significantly and rapidly.
Smaller equipment requirements
To accommodate multiple network operators on a tower and cell site, smaller antennas are preferred, with additional requirements for smaller indoor equipment that draw less power. This configuration helps to decrease power consumption and cooling requirements resulting in more efficient use of diesel generators during times of power failure. However, having smaller antennas affects transmission power, capacity and efficiency. As such, mobile operators are turning to on-site solutions that offer all these benefits, but do not compromise on quality of service, capacity or data transmission speeds.
This also extends to the backhaul network, which often poses the most significant challenge for mobile network operators, especially as mobile networks continue to evolve from 2G and 3G to LTE. For example, as mobile networks continue to evolve, backhaul network architectures will need to change from simple point-to-point to more complex ring-based architectures. Operators that choose to share infrastructure will need on-site equipment that is capable of accommodating these changes, while still offering optimal transmit speeds and reduced operational costs.
Traditionally, most network operators also used optical fiber for their high-capacity fixed line core/trunking networks. However, as tower sharing becomes more prominent fewer operators are willing to spend the capital required to enable fixed-line backhaul from shared sites due to the associated costs. Therefore, more operators are turning to wireless backhaul as a suitable solution to transport data between the cell site and the core transport telephone network.
More capacity needed
As users demand more capacity on the access portion of the network, the core/trunking network also needs to sufficient capacity to be able to transport the aggregated traffic from all these sites. Many operators have turned to high-capacity trunking microwave systems to provide the required high capacity. These high-capacity trunking microwave systems have traditionally been installed indoors, usually in a standalone rack. They were also installed in a way that radio signal strength diminished significantly before reaching the antenna at the top of the tower, ,necessitating a bigger antenna to compensate. These all-indoor configurations also required big shelters and costly air conditioning.
Developing new technologies
In an effort to improve the efficiencies of mobile backhaul to meet modern demands, tower operators and their solution providers are reconfiguring these shared sites, and new technologies are being developed to solve these challenges.
For example, split-mount trunking solutions allow for up to four radio channels on a single microwave antenna, and lower costs associated with deploying and operating ultra-high capacity microwave links for increased capacity. Smaller and lighter antenna solutions can also be lifted and installed higher on towers more easily, which helps to decrease tower space and loading requirements, making these solutions less prone to wind damage. Moving radios from the shelter to the tower, next to the antenna, further reduces deployment and operational costs and simplifies antenna connections (e.g. eliminates inefficient, long waveguides; costly unreliable pressurization/dehydration systems). In these cases, smaller shelters or cabinets can be used, which decrease air-conditioning requirements even further.
However, regardless of how tower operators are able to reduce costs and improve efficiencies, the trend of this form of infrastructure sharing is set to continue, which will help to drive increased competitiveness in mobile markets across Africa. This will have a positive impact on the prices end-users pay for mobile data and voice services, and will help to accelerate the availability of connectivity across the continent.
Technical Marketing Manager, South Africa
Typically, low-latency microwave is used to “replace” traditional-fiber based networks linking financial centers. The business driver for microwave-instead-of-fiber in low latency is the time it takes to transmit trading instructions. With microwave, latency is reduced by a few milliseconds as compared to fiber. Nevertheless, those few milliseconds can translate into a trading edge over rival investors, which means big bucks. Low latency investors will pay a premium for this edge resulting in increased revenue for low-latency microwave network operators.
However, as with most financial functions, low latency is subject to a set of stringent regulations. The scenario is doubly difficult when low-latency microwave networks transmit across international boundaries. This compares to linking financial centers within a single country, which is relatively straightforward from a regulatory perspective because there is only one set of rules. The fact is when connecting financial centers in different nations and the operator’s network has to traverse other countries’ borders, the process becomes orders of magnitude more complex. Download the complete article for a fuller examination of some of these issues and why there should be widespread support for greater international harmonization of microwave regulation.
As the summer in the Northern Hemisphere quickly draws to a close, we can look back to the beginning of the season to see what was on the mind of the backhaul market. Our international marketing manager, Ryan Bruton, gave an interview to CommsMEA covering the trends in backhaul for this time period.
In microwave backhaul, for the African market, radio links are averaging around 40 kilometers in length, says Bruton. This is due in part to climatological conditions, but other factors could also be involved, he says. However, in the Middle East, the typical microwave backhaul links are above this average—also partially due to the atmosphere and geography.
Another big trend Bruton sees this summer in backhaul includes the barriers to fiber being used in the Middle East and Africa markets. Accordingly, fiber is very difficult to trench over kilometers and kilometers of open desert. The terrain is inhospitable and very tough on fiber due to high heat and arid conditions. Not to mention bringing in the equipment necessary to install long fiber routes can be a very large obstacle if the paths lay some distance away from existing roads and other infrastructure. Going through the lush flora of Africa, such as in Nigeria, trenching fiber presents a different yet also nearly insurmountable set of barriers, with massive stands of sometimes-centuries-old trees. And clearcutting tropical rainforest to make way for a fiber backhaul route is neither cheap nor “green.”
Microwave is both the more cost-effective and greener alternative compared to fiber-optic technology for wireless backhaul. Currently achieving about 50 percent of the total market share for backhaul worldwide, microwave certainly is a driver for mobile and other wireless network operators.
Then there is always the potential for fiber to fall victim to so-called “backhoe fade,” a euphemism for the accidental cutting of fiber lines by misguided digging operations. But there is always the potential that fiber cuts are not accidental. In any event, fiber is vulnerable to cuts over the entire course of a route—from Point A to Point B. Microwave sites are isolated to a single spot where they may be assailable. At least operators have the option of “hardening” their microwave sites for maximum uptime, whereas, again, this would be too cost prohibitive in the case of fiber over an entire route.
In the mobile operator space in many countries, the national regulators are imposing so-called “buildout requirements” as a license condition on many wireless providers. In some countries, these requirements are restricted to licenses awarded by the auction process (e.g., cellular access spectrum) or block allocations while in others these conditions are attached to the majority of licenses.
Where buildout requirements are employed, a license typically has a clause that requires the licensee to build out a network/link or specified portion of a network within a certain period of time, with penalties imposed for failure to do so.
The rationale behind imposing these requirements is to ensure that after spectrum is assigned it is put to its intended use without delay. By doing this, or so the theory goes, bidders are discouraged from acquiring spectrum with the sole intent of blocking competitors’ activities without themselves offering service. Of course, the ultimate goal is the protection of spectrum—a finite and precious resource. There is no reason buildout requirements cannot be attached to any license grant, assuming that the detail of the requirements recognizes any constraints of the application for which the spectrum is sought.
Nevertheless, Aviat Networks is strongly against auctions and block allocations, but where these are a necessity then buildout requirements must be part of any award, with strong enforcement rules. The problem is that with strong enforcement operators and regulators can be at loggerheads and get tied up in court with lawsuits and countersuits for years. For example, in the U.S. you have the case of Fibertower. The FCC claims that Fibertower deliberately underbuilt its network and so moved to revoke its spectrum licenses. With the regulator moving against the operator, it came under insurmountable financial pressure and filed for bankruptcy. But even now, the operator’s creditors are fighting the FCC in order to recoup frequencies valued at more than US$100 million. So it is questionable whether this actually works in practice.
Microwave is the point
Focusing on point-to-point microwave, let’s examine the approach taken in two different countries. In the United States, for traditional link-by-link allocation, the FCC imposes an 18-month deadline by which time the link in question needs to be in service. However, in the United Kingdom, Ofcom imposes no such deadline. For certain applications, certain routes and sites are critical and can quickly become “full.” If these key locations are being filled by license applications that are not being translated into operational services, then this spectrum is effectively wasted as no one else can use it, nor is there any service being offered. Spectrum wasted in this manner reduces overall spectrum efficiency, and all spectrum authorities are motivated to ensure that spectrum is used in the most efficient way possible.
Of course having these rules is fine, but what happens when the rules are breached? In some cases, an operator will apply for an extension prior to the expiration of the original deadline; this may or may not be granted. However, the real test is what happens when the deadline passes. Ideally, what should happen is that the license(s) in question would be revoked and the associated spectrum made available for reallocation. Furthermore, if the spectrum in question was originally made available by block allocation or auction, then again, ideally, this spectrum should be returned to the pool of spectrum available for link-by-link licensing.
Additionally in shared bands, i.e., spectrum shared by the Fixed Service (FS) and the Fixed Satellite Service (FSS) should be governed by the same requirements in this instance. Therefore, unused/defunct FSS allocations/licenses should also be revoked with the spectrum being made available for reuse. In the case of FSS locations, this can have a significant effect owing to the geographic full-arc protection area that is usually associated with earth stations.
The alternative viewpoint is that the current buildout requirements are counterproductive, in their aim to foster efficient use of spectrum. One reason cited for this view is that it takes time for an equipment supply ecosystem to develop, which will serve the spectrum users. However, when we examine this claim more carefully, it seems that this is often used where the spectrum has been awarded to a single user either by block allocation or by auction. We have written before about how auctions and block allocations are unsuitable for point-to-point microwave, and the claim above is a direct result of this process, which negatively impacts the number of operators. In turn, that reduces the ranks of equipment vendors, leading to thinner competition and, therefore, decreased incentive for innovation. This situation is made worse if the operator in question chooses a band plan that is nonstandard in terms of either existing U.S. or international arrangements.
In the final analysis, it does not serve any stakeholders’ goals to have valuable spectrum allocated but unutilized. Thus, having buildout requirements would appear to be a good idea. But along with that, an effective mechanism for reclaiming and making available to others spectrum that runs afoul of these rules is paramount to making the process work for the Greater Good. In Aviat’s view, buildout requirements are a valuable tool in ensuring spectrum efficiency and as such, their use should be seriously considered in all countries.
LTE has been moving more and more to the forefront in mobile cellular networks around the world. Africa, and particularly the Republic of South Africa, is the latest hotbed of LTE rollouts, with the leading country operators of Vodacom, MTN and Cell C coming online since late in 2012. In conjunction with these LTE access rollouts, our technical marketing manager in the region, Mr. Siphiwe Nelwamondo, has been authoring a series of columns on enabling LTE in a leading regional technology media Internet site, ITWeb Africa.
Naturally, his focus has been on backhaul. In the first installment of his series, Mr. Nelwamondo looked closely at the backhaul requirements of LTE. Chief among these requirements are speed, Quality of Service (QoS) and capacity. He concluded that it is too early to close the book on the requisite parameters for supporting LTE backhaul. Part two of the features, he examined the basis on which microwave provides the technical underpinnings for LTE backhaul—especially as related to capacity. More spectrum, better spectral efficiency and more effective throughput were Mr. Nelwamondo’s subpoints to increasing capacity.
Having more spectrum for microwave backhaul is always nice, but it’s a finite resource and other RF-based equipment from satellites to garage door openers is in competition for it. Bettering spectral efficiency may be accomplished by traditional methods such as ACM and might be increased through unproven-in-microwave techniques like MIMO. Throughput improvement has wide claims from the plausible low single digit percentage increases to the more speculative of upping capacity by nearly half-again. Data compression and suppression are discussed. The truth is LTE, while data-intensive, probably will not require drastic measures for backhaul capacity until at least the next stage of LTE-Advanced.
If indeed capacity increases are necessary in the LTE backhaul, number three and the most current piece of Mr. Nelwamondo’s contains additional information. Nothing is better than having something bigger than normal or having many of the standard model. As the analogy applies to LTE microwave backhaul, bigger or wider channels will increase capacity, of course. A larger hose sprays more water. Or if you have two or three or more hoses pumping in parallel that will also support comparatively more water volume. The same is true of multiple microwave channels.
However, the most truly and cost effective capacity hiking approach is proper network planning. Mr. Nelwamondo points out that in Africa—more than some places—mobile operators are involved in transitioning from TDM planning to IP planning. While TDM planning was dependent on finding the peak traffic requirement per link, IP planning allows the flexibility to anticipate a normalized rate of traffic with contingencies to “borrow” capacity from elsewhere in a backhaul ring network that is not currently being utilized. Along with several other IP-related features, this makes determining the capacity a lot more of a gray area. Some operators solve this by simply “over-dimensioning” by providing too much bandwidth for the actual data throughput needed, but most cannot afford to do this.
The fourth and final entry in Mr. Nelwamondo’s series will appear soon on other LTE backhaul considerations of which you may not have thought. Sign up below to be notified when it is available. [contact-form-7 404 "Not Found"]
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.
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.
FirstNet is facing technological challenges as it careens toward key decisions for the Nationwide Public Safety Broadband Network. That was the key takeaway when APCO held its Public Safety Broadband Summit in Washington D.C., May 13-14. In that context, backhaul continues to be a hot topic. Typically more of an afterthought in commercial telecom systems, backhaul becomes the 900-pound gorilla in the room when defining high reliability telecom networks such as mission-critical public safety networks. This is due to the extremely high cost of fiber—CAPEX for new runs and OPEX for leasing—as well as its proven lack of survivability in worst-case scenarios.
For example, during Superstorm Sandy, 25 percent of all affected commercial mobile sites were down, and most had to be propped up by temporary microwave radio backhaul solutions due to the lengthy time needed to replace the damaged fiber. Chief Dowd of NYPD provided insight into the situation stating that the network’s reliability is defined during worst-case conditions, not during sunny days.
Aviat Networks’ APCO presentation, below, from the Broadband Summit dives deeper into these issues:
Or we can talk to you directly about your concerns for your mission-critical Public Safety network requirements.
Director, Business Development
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