Currently, there are no known ITU or North American error performance standards that address outage probability on all-packet point-to-point microwave radios. According to both the Vigants and ITU-R P.530 models, the probability of outage (i.e., Severely Errored Second Ratio) is inversely proportional to fade margin.
Truth or Myth: Higher Fade Margins Equal Better Performance?
This brings us to consider the following myth: Do higher fade margins improve error performance? Even though it makes sense intuitively, the concept of improving performance with high fade margins is not applicable to critical links—long links in low-lying, flat and humid regions. For this reason, a cautionary note needs to be disseminated among the global RF planning community.
Fade Margin and its Meaning in Point-to-Point Design
During the days of analog radios, high fade margins were required because noise was additive on a per hop basis, and any disturbance affected performance. It is important to recognize that annual or monthly outage time, not path fade margin, is the error performance objective for all-packet microwave radios. An all-packet radio will perform essentially error-free just a few dBs above threshold.
Truth 1: Critical Link C or k-Factors Reduce Fade Margin, Increase Outage Time
For long (40km+/25-miles+) and flat paths deployed in low elevations (200m/656-feet and lower) and humid areas, the geo-climatic model will yield a high geo-climatic factor (C or k-factor) that will reduce fade margin and consequently increase outage time from 300 sec/year (99.999% availability) to perhaps ~1500 sec/year (99.9952% availability). The logic is that to reduce the outage time, large (>3m/9.8-foot) antennas would be required.
Truth 2: Large Antennas Have Narrow Beamwidth, Decouple at Night
However, large antennas have a narrow beamwidth that would render the path unusable due to antenna decoupling because of dramatic changes of the k-factor at night.
Truth 3: High Output Power Does Not Accommodate High Nocturnal k-Factors
On the other hand, high output power would not accommodate very high nocturnal k-factor values and as a consequence a high fade margin would be useless—not to mention expensive to implement!
Four Principles of “Critical” Region Path Engineering
During our 54 years of existence in Silicon Valley, Aviat Networks has accumulated vast experience in the understanding of microwave radio propagation and performance in divergent geo-climatic conditions around the globe. Consequently, Aviat Networks recognizes the need to observe four path engineering commandments when implementing links in critical (i.e., low elevation, high humidity, ducting) regions as opposed to just concentrating on fade margin:
1. Adequate path clearance above suspected atmospheric boundary layers
2. Optimized antenna spacing
3. Proper antenna sizes and exacting alignments
4. Fade margin
In critical regions, wide radio channels (i.e., 28 MHz; 56 MHz) are dramatically affected by divergent tropospheric dielectric boundaries, which cannot be mitigated by high RF power or very large antennas. For these designs, sound path engineering is crucial, not necessarily high fade margin.
For additional information on high fade margins in wireless path design see our video “Check List for a Successful Microwave Link,” presented by noted microwave transmission expert Dick Laine, principal engineer for network engineering support at Aviat Networks.
Senior Network Engineer
As you know, IWCE (International Wireless Communications Expo) is just around the corner (Feb 20-24 Las Vegas) and is the premier event for government, public safety, utilities and transportation. We are excited to be exhibiting once again at this event.
We can expect to hear about 2 key themes:
1. Public Safety migration to LTE
The introduction of LTE technology into public safety networks is happening now and represents a huge change for state/local agencies. LTE is a brand new technology for this market and represents a new way of thinking for many folks. LTE brings new services and applications, different network planning and design assumptions, more capacity requirements, and more IP traffic. Understanding how to build microwave networks that best support the cost, capacity and mission critical requirements of public safety LTE will be key to building mission critical LTE data networks. Aviat has unique solutions to solve these complex challenges.
2. Security of critical infrastructure
The current and ongoing migration of public safety networks toward IP/LTE is increasing the opportunities and motivations malicious activity. As the amount of critical data rises in the broadband public safety network, security has become of greater concern. This will be a key topic at the show. Again, Aviat has a unique strong security solution which we’ll be talking extensively about at IWCE. In fact, in addition to the exhibition, we will be speaking on a panel at the IWCE show regarding cyber threats to the public safety network infrastructure on February 23rd at 3:30 – 4:45pm which we would like to invite you to attend.
Please check back after the show for an update on how things went!!
- Rajeev Suri, CEO of Nokia Siemens Networks
Recently we learned that Nokia Siemens Networks (NSN) will sell its microwave business to DragonWave. This is notable in that NSN is the first of the big 5 “Telecommunications Generalists” (the others being Ericsson, NEC, Huawei and Alcatel Lucent) to depart the microwave backhaul segment.
As stated by Rajeev Suri, NSN CEO, “Our customers….do not believe a be-everything-to-everybody strategy works anymore in this sector.” In a market where the generalists promote their ‘end-to-end’ network capability as an advantage, Suri went on to suggest that, while NSN is the first to make this move, they may not be the last – “They (NSN customers) believe that we are the first company to start making these difficult choices. I think they’re looking to some of the other suppliers to make up their mind as well. So they like it. They support it.”
This move (dare we call it a “trend?”) demonstrates what we at Aviat Networks have known for a long time—that our customers benefit from having a specialist that can bring exceptional expertise and focus to their backhaul network, since as a key part of the network and a significant OPEX driver, you need to get it right.
Specialist providers like Aviat Networks are 100 percent focused on wireless backhaul—it’s all that we do. We are committed to bridging the gap between adjacent technologies to ensure seamless inter-working. As the wireless experts, we are able to bring best in class solutions that leverage the very latest in technology innovations to solve the critical challenges of operators around the world—delivering more backhaul capacity at a lower overall total cost.
Director of Marketing
- July 27, 2011
- Aviat Networks, Business, Data Communications, Display device, element management system, EMS, Graphical user interface, Mick Morrow, Network management, northbound interface, OSS, Services, Telecommunication, Telecommunications, wireless, Wireless network
An EMS can be thought of as managing all the elements in a complex network, keeping them all in balance. Image by michael.heiss via Flickr
Managing a wireless network is essential. Radios, routers and third-party add-ons control vast amounts of valuable user data. Any wireless network downtime damages the user’s business and the operator’s long-term reputation. Thus, operators need a powerful but easy-to-use element management system (EMS) to monitor and administer all the disparate elements in their wireless communication networks.
Also, operators should be able to manage complete networks from a user-friendly interface, which must provide all the necessary information for fast network management system decision-making. And this system must be capable of complete standalone operation or being integrated into an operational support system using NorthBound Interfaces (NBIs).
Other additional functionality in the form of event management and notifications capability is also necessary in an EMS for wireless networks. An EMS should inform wireless operators about network events and device failures and let them to diagnose problems and apply network updates remotely. This reduces the time between a fault occurring and the fault being repaired. It may even allow a repair to be completed before a wireless link fails completely. For day-to-day management, operators need an EMS that can:
- Deploy, manage and auto-discover wireless equipment—including all Aviat Networks devices, partner products and third-party devices
- Display an entire network at once, via one of several map views
- Provide an overview of network events
- Deliver notifications of important network events
- Enable analysis of network events, device events and performance data
- Generate detailed reports on all aspects of a network
The ProVision EMS solution can manage all Aviat Networks wireless solutions, partner wireless equipment and third-party devices from a user-friendly GUI.
Fortunately, such a carrier-class EMS solution does exist. Aviat Networks develops its ProVision EMS based on customer demand and continues to upgrade it as per user requests and requirements. For customers, implementing ProVision is vastly more efficient than developing an in-house EMS, saving time, resources and money. Aviat Networks EMS solutions are the most cost-effective way to manage wireless solutions. Aviat Networks works closely with customers to make sure that ProVision is user-friendly. The goal is that ProVision EMS allows operators to manage their networks proactively—rather than reactively—and with reduced network operating costs.
Look for future blog posts on must-have EMS data features and stats on operators using carrier-class EMS.
Sr. Product Marketing Manager, Aviat Networks
- July 22, 2011
- Aviat Networks, backhaul, Business, Dick Laine, Internet Protocol, microwave, NASA, Nikola Tesla, Telecommunication, Telecommunications, wireless, Wireless Gigabit Alliance
This image of microwave energy in a "total sky" picture of the known universe shows it's everywhere in primordial space, more than 13 billion years ago.
Microwaves are as old as the beginning of the universe. Well, they’ve been around for at least 13.7 billion years—very close to the total time since the Big Bang, some 14 billion years ago. However, we don’t want to go that far back in covering the history of microwave communications.
Having just observed the 155th anniversary of the birth of Nikola Tesla, arguably the most important inventor involved in radio and wireless communications, this is a good time to take a broader view of the wireless industry. If you have been in the wireless transmission field for some time, you are probably familiar with Dick Laine, Aviat Networks‘ principal engineer. He has taught a wireless transmission course for many years—for Aviat Networks and its predecessor companies.
The embedded presentation below comes from one of those courses. In a technological field filled with such well-educated scientists and engineers from some of the finest universities and colleges, it’s hard to believe that microwave solutions and radio itself started in so much controversy by men who were in many cases self-taught. Dick’s presentation goes over all of this in a bit more detail. Hopefully, it’s enough to whet your appetite to find out more. If you like the presentation, consider hearing it live or another lecture series on wireless transmission engineering at one of our open enrollment training courses.
- July 1, 2011
- antenna, Aviat Networks, Business, Comsearch, Equipment, FCC, Federal Communications Commission, Fixed Wireless Communications Coalition, FWCC, Ian Marshall, microwave, Network service, Radio, Regulatory Manager, Telecommunication, Telecommunications, wireless
Image via Wikipedia
In response to the recent FCC docket 10-153, many stakeholders proposed relaxing antennas requirements so as to allow the use of smaller antennas in certain circumstances. This is an increasingly important issue as tower rental costs can be as high as 62 percent of the total cost of ownership for a microwave solutions link. As these costs are directly related to antenna size, reducing antenna size leads to a significant reduction in the cost of ownership for microwave equipment links.
The Fixed Wireless Communications Coalition (FWCC), of which Aviat Networks is a major contributor, proposed a possible compromise that would leave Category A standards unchanged while relaxing Category B standards. The latter are less demanding than Category A, and after some further easing, might allow significantly smaller antennas. The rules should permit the use of these smaller antennas where congestion is not a problem, and require upgrades to better antennas where necessary.
A further detailed proposal from Comsearch proposed a new antenna category known as B2, which would lead to a reduction in antenna size of up to 50 percent in some frequency bands. This would be a significant cost saving for link operators.
At the present time, the industry is waiting for the FCC to deliberate on the responses to its 10-153 docket, including those on reducing antenna size.
See the briefing paper below for more information.
Regulatory Manager, Aviat Networks
- June 24, 2011
- ACM, Adaptive Modulation, Business, ComReg, Frequency range, Ian Marshall, Ireland, microwave, Regulatory Manager, Spectrum, Spectrum Management, Telecommunications, wireless
Image via Wikipedia
The Irish communications regulator, ComReg, recently issued a consultation on its spectrum management strategy for 2011-2013. This was a wide-ranging consultation covering all aspects of spectrum management. However, in terms of interest to the microwave fixed point to point business were the following items:
A stated intention to open new bands for fixed point to point microwave wireless backhaul at 26GHz, 28GHz and 31GHz in line with the relevant ECC recommendations. In addition, ComReg requested comments on the following proposals regarding the use of Adaptive Modulation (ACM) and Cross Polarization (XPIC).
“Given the benefits identified from the use of Adaptive Coding & Modulation (ACM) in terrestrial Fixed Links, ComReg is proposing to make the deployment of ACM mandatory for all new fixed link applications across all fixed link frequency bands from 01 June 2012,” the consultation reads.
“With a view to encouraging spectrum efficiency in congested frequency bands, ComReg is proposing to make dual polarization mandatory for all new fixed link applications, where more than one link is required on the same path in the same frequency band, from 1 June 2012.”
The above two proposals demonstrate ComReg’s forward vision in embracing new wireless technology to increase the viability of using microwave solutions for critical traffic. Compared with some other regulators around the world, this is a welcome and refreshing approach.
Also ComReg indicated its intention to explore the possibility of using alternative licensing schemes, e.g. light licensing or link registration, in bands above 50GHz that are under consideration for opening in Ireland. Let me know your thoughts.
Regulatory Manager, Aviat Networks