Lessons Learned: Transitioning from TDM to IP
- October 18, 2013
- Aviat Networks, cell phone networks, Hadi Choueiry, Internet Protocol, LTE, Quality of service, tdm, Telecommunications, Time-division multiplexing, Voice over Internet Protocol, Voice over IP
Cell phone tower near Lozen, Bulgaria. Photo credit: Plamen Agov • studiolemontree.com [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons
Aviat Networks has been there all along the way, helping operators design and deploy aggregation systems. We’ve seen and learned a lot as some of the leading mobile phone carriers have upgraded their networks. Now as LTE works its way into mainstream status, cell phone networks are transitioning to full-IP, the underlying technology of LTE.
85 Microwave Operators tell us their Biggest Backhaul Challenge
- July 30, 2013
- backhaul, custom survey, Ethernet, internet, Internet Protocol, microwave, microwave antennae, MIMO, Mobile network operator, network throughput, quantifiable data, TCO, Total Cost of Ownership
England: Campion Hills communications mast with microwave antennae. Photo credit: David Stowell [CC-BY-SA-2.0], via Wikimedia Commons
85 mobile operators were selected and surveyed globally, including a good cross-section from both developed and emerging markets. The respondents were screened to ensure that they all had a stake in microwave-specific backhaul: 93 percent had deployed microwave and the rest had plans to deploy it. In fact, 45 percent were categorized as heavy microwave users—those where more than 50 percent of their cell sites were served by microwave backhaul.
So we asked this select group, which consisted of mostly planners, engineers and strategy leaders, “What is the biggest challenge your company faces regarding the future development and deployment of microwave backhaul?”
The results were interesting in that “total cost of ownership” actually eclipsed “increasing capacity” as their biggest challenge, as shown in the pie chart of survey responses below.
4G Upgrade Path Drives Backhaul Migration in Kenya
- July 10, 2012
- 3GPP Long Term Evolution, Africa, Ethernet, Internet Protocol, Kenya, Mobile network operator, Safaricom, tdm, Telecommunication, Time-division multiplexing, WiMAX
Burgeoning WiMAX and 3G data traffic from subscriber devices such as Safaricom’s Internet Broadband Dongle (with SIM Card) are driving the mobile operator to migrate from TDM to hybrid microwave backhaul. (Photo credit: whiteafrican via Flickr)
Migrating legacy mobile backhaul networks that were designed for TDM traffic to add support for high-speed Ethernet data for 3G and 4G mobile technologies is one of the biggest challenges for operators worldwide. Each case is unique and poses its own quirks and potential pitfalls. Mobile operators must juggle new technologies, cost pressures and the need to maintain existing services or risk driving customers to the competition.
For Safaricom, the leading mobile operator in Kenya and one of largest in all Africa, the case involved preserving its E1 capacity for voice calls and simultaneously adding Ethernet/IP bandwidth for burgeoning 3G and WiMAX data traffic. As many mobile operators have done in the past, Safaricom built its network over time. Many parts of the network are still legacy 2G TDM technology. However, things are changing rapidly, with 3G subscriber numbers up 85 percent in 2011 year over year.
Many of these subscribers are consuming ever-increasing amounts of data bandwidth. Safaricom’s TDM based backhaul, making use of Ethernet-to-E1 converters, is finding it hard to keep up with demand. To help resolve the situation, the operator called on Aviat Networks, one of its incumbent solution providers. Using its market leading hybrid radio solution, the modular Eclipse microwave networking platform, Aviat Networks enabled Safaricom to add IP data capacity as necessary while keeping E1 capacity for voice calls.
In addition, the stage has been set for Safaricom to make the eventual migration to all-IP backhaul. With the modular Eclipse platform, it can transition on its own schedule. For more information, read the complete Safaricom case study in the frame below or download the PDF:
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Record 180 km Hybrid Diversity IP Microwave Link
- June 12, 2012
- Atlantic Ocean, Aviat Networks, Belize, frequency diversity, Honduras, hybrid diversity, Internet Protocol, microwave, Microwave transmission, Space Diversity
Survey view from Belize toward Honduras, at 1000 m AMSL
Link between Honduras and Belize Crosses Water and Land
Last year I wrote about the world’s longest all-IP microwave link, stretching 193 km over the Atlantic Ocean in Honduras. Aviat Networks and Telecomunicaciones y Sistemas S.A. (TELSSA) designed and implemented this link together. This year, Aviat Networks and TELSSA again worked together to build another link and achieve another record—an Eclipse microwave link between Honduras and Belize that crosses 75 km of the Atlantic Ocean and 105 km of rugged terrain for a total path length of 180 km. This is a new world record for a hybrid diversity microwave link!
After the success of implementing the 193km link over water, Aviat Networks and TELSSA were eager to meet the challenge to connect Honduras and the neighboring nation of Belize using a single microwave link. Aviat Networks network engineers and TELSSA engineers were able to use their extensive knowledge of local propagation conditions, thorough understanding of long path design principles and precise installation practices to successfully implement this 180km microwave link.
Long Path Design Considerations
As outlined in the article last year for the longest all-IP hop, a deep understanding of path design considerations and experience in microwave transmission path design are necessary to successfully complete a long path design. Key considerations involved:
- The effect of antenna diameter on highly refractive paths
- Precise alignment of the antennas to mitigate the effect of refractivity
- Optimum RF and space diversity spacing to counter elevated divergent dielectric layers
- Deterministic prediction of the variations of atmospheric conditions
- Multi-path propagation delay
To read more about this world-record Hybrid Diversity IP microwave link, download the full article.
Ivan Zambrano
Senior Network Engineer
Aviat Networks
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3 Models for Microwave Link Error Performance? Laine Explains
- May 11, 2012
- Aviat Networks, bell system technical journal, Dick Laine, International Telecommunication Union, Internet Protocol, ITU-R, microwave, microwave link, microwave link design, microwave link error performance, Microwave transmission, Principal Engineer, Radio Head, Radio Head Video Technology Series, Radio Heads, Radiohead, reliability or error performance, Richard Laine, tdm, Time-division multiplexing, Vigants, wireless, wireless engineering
In the second episode of Aviat Networks’ Radio Head Technology Series, Principal Engineer Dick Laine explains ITU-R models for Fixed Wireless Systems.
As most radio engineers know, Vigants calculations, which are discussed in a broadly cited Bell System Technical Journal article, are widely used to determine reliability or error performance for microwave link design. In Video 2 of Aviat Networks’ popular Radio Head Technology Series, which is now available for viewing, Principal Engineer Dick Laine explains how he uses Vigants calculations in conjunction with the three completely separate ITU-R Fixed Wireless System (FWS) models for TDM.
Because of all these models, he likes to use Vigants calculations as a “sanity check” to see that he is close to the correct result for his path engineering plans. The free Aviat Networks’ Starlink wireless path engineering tool can be used to handle Vigants calculations for Aviat Networks’ and other vendors’ equipment.
Can’t wait to hear more of Dick’s experienced views on microwave radio transmission engineering? You can get ahead of the learning curve by registering for the series and get these videos sent to your inbox as soon as they are released.
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Migrating Utility Networks to Smart Grid with Hybrid Radios
- November 20, 2011
- Internet Protocol, Renewable energy, smart grid, Smart meter, Telecommunication, Time-division multiplexing
What is the best migration strategy for utility networks migrating to Smart Grid using Hybrid Radios? We look at the technology choices that are available to support legacy TDM and IP-based services and investigate the many demands placed on utility networks. Demands include seamless migration, increased capacity, security, and interoperability.
We believe a hybrid network is the best solution and we explain why in this white paper:
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4 Realities about Rain Fading in Microwave Networks
- August 23, 2011
- Aviat Networks, backhaul, Dick Laine, Frequency range, Internet Protocol, microwave, Microwave transmission, Principal Engineer, Rain Attenuation, Rain Fade, Rain Fading, Telecommunication, Time-division multiplexing, wireless
Rain fading (also referred to as rain attenuation) at the higher microwave frequencies (“millimeter wave” bands) has been under study for more than 60 years. Much is known about the qualitative aspects, but the problems faced by microwave transmission engineers—who must make quantitative estimates of the probability distribution of the rainfall attenuation for a given frequency band as a function of path length and geographic area—remains a most interesting challenge, albeit now greatly assisted by computer rain models.
A surprising piece of the puzzle is that the total annual rainfall in an area has almost no correlation to the rain attenuation for that area. A day with one inch of rainfall may have a path outage due to a short period of extremely high localized rain cell intensity, while another day of rain may experience little or no path attenuation because rain is spread over a long period of time, or the high intensity rain cell could miss the microwave hop completely.
Over the years, we have learned a lot about deploying millimeter wave microwave hops for our customers:
- Rain outage approximately doubles in each higher millimeter wave band, e.g. 18 to 23 GHz
- Rain outage is directly proportional to path length—assuming a constant fade margin for each hop
- Rain outage in tandem-connected short hops is the same as for a single long hop—if they have the same fade margin
- Multipath fading in optimally aligned millimeter wave hops does not occur during periods of heavy rainfall, so the entire path fade margin is available to combat rain attenuation fades
More information about assessing rain-induced attenuation is available in our white paper, Rain Fading in Microwave Networks.
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Evolution of Microwave: History of Wireless Communications
- 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.
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Hybrid Microwave for Wireless Network Backhaul Evolution
- July 20, 2011
- 3GPP Long Term Evolution, Aviat Networks, backhaul, dual ethernet, Ethernet, hybrid ethernet, hybrid microwave for smooth network evolution, Internet Protocol, microwave, Microwave backhaul, Microwave transmission, Next generation network, tdm microwave systems, Time-division multiplexing, wireless, Wireless Backhaul
Image via Wikipedia
There is no one-size-fits-all wireless network backhaul solution. What will work for some operators’ mobile backhaul will not work for others. Many operators have large installed bases of TDM infrastructure, and it is too cost-prohibitive to uninstall them wholesale and jump directly to a full IP mobile backhaul. There is going to be a transition period.
The transition period will need a different breed of wireless solutions. Fourth Generation Hybrid or Dual Ethernet/TDM microwave radio systems provide comprehensive transmission of both native TDM and native Ethernet/IP traffic for the smooth evolution of transmission networks. They will enable the introduction of next-generation IP-based services during this transition period.
We will explore this category of digital microwave technology for wireless backhaul, which is becoming ever more important as the 4G LTE wireless revolution gets underway with all due earnestness, even while the current 3G—and even 2G—networks continue to carry traffic for the foreseeable future.
Our current white paper builds on Aviat Networks‘ previous April 2010 white paper titled “What is Packet Microwave?” and provides market data from recent industry analyst reports that demonstrate the significant and continuing role of TDM in mobile backhaul networks and some of the prevailing concerns of operators in introducing Ethernet/IP backhaul services.
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If you’d like to talk to someone about the ideal wireless network backhaul solution for you, please click here.