As you may have seen, Aviat has been very vocal about the benefits of extra high power (EHP) radios on network designs. Most of these discussions have been about the cost savings benefits of high output power in the form of more distance, smaller antennas, or more capacity. Continue reading
Back in April the telecom experts over at CommLawBlog weighed in on a simmering issue in the 70-80GHz radio space. Since October 2012, the Federal Communications Commission (FCC) has mulled over a motion by the Fixed Wireless Communications Coalition (FWCC) to relax rules for flat panel antennas as well as a 2013 waiver to the existing rules while it considers a new rulemaking.
Lack of taking any action on any of these filings has left the backhaul industry in a quandary. With viable radio solutions ready to deploy in the 70-80 GHz frequency ranges, the only holdup has been a technical requirement that FCC rules place on the radiation pattern of the very thinnest of flat panel antennas. These rules were originally formulated for an era where microwave radios were used for links that spanned 1 to 5 kilometers.
In the new urban reality for small cells, the distances between mobile base stations will be measured in hundreds of meters. At these lengths, the radiation patterns of flat panel antennas will not materially increase interference, to paraphrase language the FCC itself has used previously when approving use of smaller antennas in the 6, 18 and 23 GHz bands, circa 2012.
With small cell wireless in close-in city settings, both mobile and non-mobile subscribers have a heightened sense of awareness, and they will take extra notice of backhaul radios with prominent parabolic dishes that stick out like sore thumbs. With their figurative and literal low profiles, flat panel antennas provide the critical missing link in ameliorating the aesthetics concerns that many feel toward old, bulky microwave installs. While these hulking communications devices were fine on towers at long haul sites way out by the interstate freeway or high atop skyscrapers in the heart of the business district, when they are situated on the side of a residential building the modern-day urbanite will not tolerate these telecom equipment eyesores.
In reality, there is very little for the FCC to decide upon. While the telecom regulator here in the United States has its own rules, regulators in much of the rest of the world use the ETSI standards. Actually, the standard in effect is of little consequence. The point of fact is that the flat panel antennas in question before the FCC have been approved for use in all these ETSI countries without any significant drawbacks being reported in nearly three years of use. Even the FCC’s companion agency to the north, Industry Canada, has given tentative go-ahead to flat panel antennas for use with 70-80GHz backhaul radios, with the implicit understanding that they will receive formal approval if no unforeseen snags occur in final rule drafting.
So while the rest of the small cell community enjoys a flat panel world, the U.S. is walking a tightrope of red tape in hopes that some decision is made—soon.
Full disclosure: Aviat Networks is the filer of the 2013 waiver request and is a member of the Fixed Wireless Communications Coalition. Aviat Networks is legally represented by Fletcher, Heald & Hildreth, PLC, the host of CommLawBlog.
Competitive licensing of fixed microwave backhaul bandwidth is a bad idea. And it should not go any further. The reasons why are laid bare in a new article in IEEE Spectrum by former electrical engineer and current telecom law firm partner Mitchell Lazarus. In general, he argues against federal spectrum auctions for microwave frequencies, and in particular for fixed microwave links. Undoubtedly, readers are familiar with the large cash bounties governments around the world have netted from competitive bidding on cellular bandwidth—first 3G and now 4G. An inference can be drawn from Lazarus’ article that some governments (i.e., the United States, the United Kingdom) had in mind a similar, if perhaps smaller, revenue enhancement through competitive auctions of microwave channels.
The problem lies in the fallacious thinking that operating fixed point-to-point wireless backhaul bandwidth is comparable to that of mobile spectrum. Whereas mobile spectrum license holders can expect to mostly—if not fully—use the frequencies for which they have paid top dollar, the same has not historically been true of license holders of microwave backhaul bandwidth. In most cases, mobile license holders have a virtual monopoly for their frequencies on a national, or at least regional, basis. Their base stations send and receive cellular phone signals omnidirectionally. They expect throughput from any and all places. So they have paid a premium to make sure no competitors are on their wavelengths causing interference.
On the other hand, U.S. holders of microwave backhaul licenses have specific destinations in mind for the operation of their point-to-point wireless networks. They only need to communicate between proverbial Points A and B. And, historically, they have only sought licenses to operate in their particular bandwidth on a particular route. They had no need to occupy all of their licensed frequency everywhere. That would be a waste. They just have to make sure they have a clear signal for the transmission paths they plan to use. To do that, before licensing, they would collaborate with other microwave users in the vicinity and a frequency-coordination firm to establish an interference-free path plan. Any conceivable network issues would usually be resolved at this stage prior to seeking a license from the Federal Communications Commission. Essentially, the FCC is just a glorified scorekeeper for fixed microwave services, passively maintaining its transmitter location license database.
But starting in 1998, with dollar signs in their eyes, governmental spectrum auctioneers started to sell off microwave frequencies in block licenses. The need for fixed microwave wireless services then was growing and has only grown fiercer with each additional iPhone and iPad that has been activated. However, access device throughput demand on one side of a base station does not necessarily fully translate all the way to the backhaul. Lazarus points out the example of now defunct FiberTower and its failure to make block microwave licenses work economically. After buying national block microwave backhaul licenses at 24 and 39 GHz, Lazarus notes, the firm resold the frequencies to Sprint and a county 911 emergency network operator. But those were the only customers. Lacking a robust enough utilization of its licensed backhaul frequencies, FiberTower had several hundred of its licenses revoked by the FCC and was forced into bankruptcy November 2012.
Subsequent auctions have attracted far fewer bidders and generated much less income for the Treasury Department. Much bandwidth has lain fallow as a result. And infrastructure buildout has stagnated.
Regulators should return the microwave backhaul licensing process to that of letting wireless transmission engineers cooperate informally among themselves, with the help of frequency-coordination firms, to arrive at fixed point-to-point wireless plans in the public interest. These are then submitted only for maintenance by the FCC or other regulators for traditionally nominal license fees—currently $470 per transmitter site for 10 years in the U.S., per Lazarus.
Forget the quixotic quest for chimerical hard currency. The commonweal demands it. You should demand it of the regulators—you can still give input regarding this scheme in some jurisdictions where it is under consideration. Clearly, the most efficient use of spectrum is to make it openly available to all because it means that every scrap of commercially useful spectrum is picked clean. We welcome your comments pro or con.
- Qualcomm execs: Wireless spectrum is maxed out (reviews.cnet.com)
- Would Millimeter Waves be preferred Metrocell backhaul option? (ytd2525.wordpress.com)
- E-Band Global Regulation Roundup (aviatnetworks.com)
- Wireless Regulators Move to Prevent Spectrum Waste (aviatnetworks.com)
- Revenues From Macrocell Mobile Backhaul Gear To Reach $9.7bn In 2016 (misco.co.uk)
Aviat Networks has been deploying LTE networks for well over a year now to operators globally, including the largest live commercial LTE network in operation today. So, it’s probably a good time to reflect on some key observations and lessons learned to date. Here are the top 3 things we’ve learned from our LTE microwave backhaul deployments that are most notable:
1. LTE backhaul capacity needs are being easily addressed by packet microwave:
– When it comes to capacity there is a perception that fiber is the only answer. The reality is that based on current LTE deployments, 50Mbps is more than adequate for most LTE cell sites today. Yet, for comfort and long term growth most of our customers are licensing and deploying 100-200Mbps of microwave capacity to their LTE equipped cell sites. For intermediary sites that aggregate traffic, link aggregation techniques are being utilized to effectively bond multiple channels for higher capacities, all well within the multi Gbps reach of advanced microwave systems, such as ours.
2. Ease of deployment and fast time to market (TTM) are critical for success:
– This LTE operator quote speaks volumes regarding the real challenge he faces: “Whoever can deliver the quickest with the least amount of pain will win most of the business”. TTM is most crucial for operators trying to stay one step ahead of their competition… more markets served, better coverage etc. To address this, we have seen a growth in our customers seeking a one stop shop approach for LTE microwave backhaul deployment where we engineer, configure, test, and deploy the full end–to-end system, providing overall project management, frequency coordination, installation and a host of other services. The fact that most microwave systems can be installed in a few weeks as opposed to months for fiber, is also playing a key role in microwave growth in areas like North America where microwave penetration is low, but growing as a result of LTE rollout.
3. Backwards compatibility with multivendor interoperability is key:
– It’s all about LTE, right? Well, yes and no. LTE is driving the new investment and deployments, but the reality is that 2/3G will be around for a long time. So, while the new deployments are driven by all-IP LTE, there are still ‘legacy’ T1/E1s still hanging around that also need to be backhauled. This has been a perfect fit for Aviat’s all-in-one Hybrid (TDM+IP) and All-IP microwave systems, which allow our customers to easily software configure their mix of traffic. So, while the bulk of the transport bandwidth is provisioned for IP to support LTE, some is still reserved for good ‘ole TDM.
– Another related aspect is multivendor interoperability across a variety of product types. The backhaul market has flourished in the last few years as we know, and so has the variety of cell site switches, routers, packet optical devices etc. that our microwave systems interoperate with to fulfill our customers ‘end-to-end’ LTE backhaul solution. Consistent Carrier Ethernet standards applied across both the microwave and fiber core makes this very straightforward when it comes to provisioning Ethernet backhaul services, supporting packet network synchronization, and managing these services.
So, in summary, I would say we’ve learned that packet microwave is well suited for LTE capacity needs; it can be rapidly and easily deployed; and provides great flexibility for legacy services and multi-vendor interoperability. But the best proof of all this is in our customers’ live networks.
Fore more information on LTE microwave backhaul and a customer case study click here.
It has come a long way in its first year and it is still the only blog that specializes in wireless transmission!
In the past year the blog has received more than 45,000 visitors. Topics have ranged from “Small Cell Mobile Backhaul: The LTE Capacity Shortfall” to “Just How Recyclable is my Radio?” and it has the luxury of a wide range of contributors.
The post that received the most hits was “What is Asymmetrical Link Operation?” and the post that received the most comments was “The World’s Longest All-IP Microwave Link”?
Thanks to the contributors and the people who took the time to comment.
We are looking forward to more insightful posts in 2012 including a daily commentary from Mobile World Congress in February. Stay tuned.
Balancing cost and performance is a tough act for most operators dealing with telecom networking, especially when it comes to equipment procurement. Getting all the bells and whistles can sometimes result in having a lot of options to choose from. Often times microwave users have to juggle with a variety of radio options that suit a particular site requirement, for example, having to select between low power or high power radios to meet varying distance or system throughput/gain needs. Depending on location and licensing requirements, this may even translate into different products types for different frequency bands. More products result in more spares to maintain in inventory, along with added support and maintenance, inevitably leading to higher costs.
To help address this challenge, Aviat recently unveiled the industry’s first universal outdoor unit (ODU) to support software- defined base and high power modes in a single ODU, with Aviat’s unique Flexible Power Mode (FPM) capability. FPM allows operators to optimize both cost and performance, minimizing their overall total cost of ownership, by paying for the power they need only when needed. As a result, operators can procure a single ODU for multiple locations and via a simple software licensing mechanism, remotely adjust the transmit output power to meet the needs of a particular site. No need to spare multiple radios, nor deal with the operational burden of managing and supporting a variety of product options.
Additionally, operators can apply this flexibility to migrate from legacy low power, low capacity radios to a high power and performance ODU to support much greater link throughput, without having to change their installed antennas. This minimizes both their CAPEX and OPEX while migrating their network from a legacy low capacity TDM microwave link to a high speed Ethernet one.
So while juggling may still be a well needed skill to survive in Telecom, Aviat is reducing the load when it comes to microwave networking. Click here to find out more.
Senior Solutions Marketing Manager
- Hybrid Microwave for Wireless Network Backhaul Evolution (aviatnetworks.com)
Last year one of our microwave competitors introduced a new development for the point-to-point licensed microwave market – asymmetrical link operation. There are some very real challenges with the growth of mobile multimedia that are driving interest in this approach. However there are numerous harsh realities involved in introducing such a ‘radical’ technique into the relatively conservative licensed microwave industry. The myriad of Regulatory studies and approvals that will be needed to enable asymmetric operation to be deployed in existing bands means that it could be years, if ever, before asymmetric links can be deployed in most countries around the world.
Today’s Licensed Microwave Bands are Exclusively Symmetric
In current licensed microwave bands and all commercially available equipment today, transmission is symmetric – i.e., the same capacity and bandwidth in both directions. Frequency bands are arranged for frequency division duplex (FDD) operation, where two identical channels are used for Tx (‘go’) and Rx (‘return’). Asymmetric operation is usually reserved for unlicensed time division duplex (TDD) radios, which use a single channel for both go and return.
The proposed Asymmetrical scheme is based upon a concept called ‘Spectrum Borrowing’, where frequency spectrum is taken from the upstream direction of a lower capacity link, and given to the downstream direction of an adjacent higher capacity link.
A second (but related) proposal has been also tabled to amend the standard channel options from the current 7, 14, 28, 56 MHz to an n*7MHz arrangement (i.e. 7, 14, 21, 28, 35, 42, 49, 56 MHz), which is required to support the asymmetric concept.
What is driving the need for this Asymmetry?
The underlying rationale is that in 3G and 4G mobile networks, a majority of the traffic over the network is increasingly web- and video- based, meaning more capacity is needed in the backhaul network in the direction towards the base station, and less in the opposite direction back to the core.
However, while this is true today, new emerging mobile applications such as video chat, video uploading, P2P sharing, and new cloud based services (eg: iCloud), have the potential to change the imbalance between upload and download demand over the longer term. This presents a challenge for the proposed asymmetric implementation, which is fixed in nature, not dynamic. This means that the link has no way to adapt to instantaneous uplink/downlink traffic demand, or to change over time as more uplink capacity is needed. Changing this ratio could prove to be very difficult once an asymmetric link is in place and has been operating for several years.
Making substantial changes in the way that licensed microwave bands are used is not a simple process, since strict regulations and standards at the international and national level have been put in place to ensure that links deployed in these bands are assured to be virtually interference free.
A proposal has now been submitted to the Electronic Communications Committee (ECC), the Regulatory Body responsible for amending the channel plans for the existing frequency bands, a part of the European Conference of Postal and Telecommunications Administrations (CEPT), representing 48 countries throughout Europe and Russia. The ECC has agreed to set up a study group to examine the proposal, which is due to report their finding in February 2013.
If the ECC agrees to amend the channel plans to permit asymmetric operation, which may not happen before 2015, the national regulator in each CEPT country will then have to decide whether or not to adopt the recommendations. Further lobbying will also be necessary beyond the CEPT region, for example with the FCC in the USA, to successfully influence regulatory policy in favor of Asymmetrical operation.
A Long Road to (Possible) Adoption
In summary, asymmetrical operation may be a potentially useful technique to improve the efficiency of backhaul networks and frequency utilization. However, introduction of this technique will be extremely difficult within existing congested frequency bands, and will face significant and lengthy regulatory scrutiny and approval before we will see widespread adoption.
Director of Marketing
Public safety agencies with first responder assignments, mobile service providers with national footprints, and utilities companies all have communication networks carrying mission critical applications. These networks require robust, secure and powerful microwave radios.
So what are the defining characteristics of Mission Critical Microwave?
- Hybrid (TDM and IP): Native TDM, native IP. No proprietary emulation or encapsulation.
- RF performance: Superior system gain. Adaptive Coding and Modulation.
- Reliability: 100+ year proven terminal (1+0) MTBF.
- Strong Security: Secure Management to prevent unauthorized access. Secure payload encryption to prevent eaves-dropping.
- Bullet Proof Redundancy: Full port, card, system level redundancy. Integrated T1 loop switch (USA).
- Physical Design for Usability: Front access, no hidden cables. Compact footprint. Expansion port.
But delivering Mission Critical Microwave extends far beyond products and deals with the way a company behaves and treats its customers including:
- A mindset that integrates uncompromised commitment to design and to building the most robust, secure and dependable microwave radios;
- A culture of innovation to ensure the most innovative new microwave products are being developed to meet the needs of your critical applications;
- Engineering professionals that are there at your side before, during and after any equipment deployment, to help you at every step of the way;
- A commitment to customer service and support so that customers can depend on their chosen vendor.
At Aviat Networks, we believe one of the things that sets us apart is our focus on Mission Critical Microwave. For critical applications it’s extremely important that customers have comprehensive local support at their fingertips. Our products are usually supported locally, so our customers know they’ll have immediate access to professional engineers when they need them, without waiting for out-of-country spares or support, including escalation to Tier III level technical support if needed.
At Aviat Networks, our engineers have been designing and building microwave networks for over 50 years. We are the microwave experts, because it’s all we do.
Senior Product Marketing Manager
Typically, a small number of DS1s has been sufficient to service 2G and 2.5G base stations, but with the data capacity needed for advanced 3G and 4G HSPA/LTE applications, new strategies and even new technologies being evaluated.
More network capacity translates to more backhaul capacity. This additional capacity can be more efficiently delivered in IP/Ethernet. Among the many technologies available, IP/Ethernet is consistently recognized as the transport media of choice for expanded backhaul services.
For many operators the introduction of Ethernet will be an overlay on top of existing TDM (voice) network connections given their huge investment in their TDM infrastructure. This will typically involve gradual migration using data overlay, with a decision at some future point to further migrate to an all-packet-based network. The transition phases may well include instances where there is a need to transport Ethernet alongside TDM, or Ethernet over TDM, and do so in a flexible, secure and cost efficient way.
It is clear is that the traffic requirements in carrier networks are becoming more advanced. To support real-time, two-way digital communications, an IP-enabled, communication pipeline must be established.
Our paper reviews the technology choices that are available to support legacy TDM and IP-based services when migrating to IP/MPLS. Network migration should consider the many demands such as seamless migration, increased capacity, cost, and security. Hybrid networks that can transport native TDM alongside native IP are the best solution to successfully tackle the many requirements for mobile carrier networks.