Converged Microwave Traffic Emerges in Africa

Aviat-Networks-Technical-Marketing-Manager-Siphiwe-Nelwamondo-discusses-Microwave-and-IP-Convergence-with-Engineering-News-January-23-2015

Convergence: Photo credit: rkimpeljr / Foter / CC BY-SA

In South Africa, as in many emerging markets, wireless backhaul has long been a proverbial bottleneck to network growth. Due to cost and logistics, fiber optic technology remains out of reach as a practical solution for most aggregation scenarios, save for urban applications where population density and shorter routes can justify the exorbitance.

Now with the advent of higher speed, higher throughput mobile phones and tablet PCs, higher-order networking technologies are being pressed into service. Standard microwave radio, while cost efficient and effective for crossing far-flung forests, monumental mountains and desiccated deserts with traditional payload such as voice calls and moderate data rate applications, was not designed for the connectivity and capacity requirements of Layer 3 services. Thus, the bottleneck has grown still narrower. Even to the point where standard microwave radio might be hitting its upper threshold for serving mobile broadband.

Technical marketing manager, Siphiwe Nelwamondo, recently sat down with Engineering News, to discuss these issues and the present and future of microwave radio backhaul in South Africa and across the continent. In addition, he delved into how microwave networking is bridging the radio-IP gap for Layer 3 services by running IP/MPLS protocols on converged microwave routers.

As more and more mobile services get pushed out to the edge of the access network, the imperative for Layer 3 will only grow. Even as 3.5G and 4G mobile users who depend on full-IP increase in number, a majority of second- and third-generation subscribers will continue to rely on circuit-based technology. Not to worry, Nelwamondo covers how TDM telephony will be supported in a converged microwave and IP environment.

The full article goes on to discuss how mobile operators will strategize providing enterprise services from the cellular base station with microwave networking, virtual routers and more.

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Lessons Learned: Transitioning from TDM to IP

Cell-phone-tower-near-Lozen-Bulgaria-Aviat-Networks-network-solutions-architect-Hadi-Choueiry-recounts-3-TDM-to-IP-lessons-learned-18Oct13

Cell phone tower near Lozen, Bulgaria. Photo credit: Plamen Agov • studiolemontree.com [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons

The transition from the Time Division Multiplexing (TDM) cell phone networks of the 2G and 3G mobile era has been a long time coming. However, the mobile industry seems to be at one of its proverbial inflection points where IP (Internet Protocol) technology is ascendant and TDM has begun the long but inevitable decline into legacy status.

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.

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Evolution of Trunking Microwave Radios

Aviat WTM 6000 trunking microwave radio

Aviat WTM 6000 trunking microwave radio

Back in the day, trunking microwave radios were huge power-hungry beasts that consumed vast quantities of power and space at equal rates. They were complex “animals” that took days to install and hours to configure. Then they had to be looked after like well-loved but aged members of the family—with care, all due respect and consideration. Over time, components went out of adjustment and had to be brought back into line through various tuning routines, but overall they did their job as the super-reliable backbone of the POTS (i.e., Plain Old Telephone Service).

Jump forward a few decades and the latest trunking microwave solutions are elegant and graceful—almost svelte. With their current high levels of electronic integration, a complete repeater system can stand in a single rack space—unheard of until the most recent products. Furthermore, these new systems consume dramatically less power—a typical 3+1 system (i.e., four transceivers) consumes less than 400 watts. So now, backbone operators can save significantly on operating expenditure because of decreased space and power requirements at their microwave radio shelters.

Evolving microwave systems from analog to digital microwave systems carrying digital payloads was a rocky and dangerous path. The next migration from TDM payloads to IP payloads appears to be just as treacherous. How can a traditional TDM backbone radio, typically configured with N+1 radio protection switching, be reconfigured to transport a non-TDM payload that does not suit N+1 switching? IP transport is a completely different environment altogether! Luckily, trunking radio system designers have not ignored the Internet revolution and are perfectly aware of these challenges. In fact, well-appointed trunking microwave radio systems allow a graceful evolution from TDM to IP, with capability to transport both types of traffic simultaneously—and with their own ultra-reliable protection schemes!

Today, trunking microwave radios can support both TDM and IP seamlessly, offer robust radio performance and highly reliable switching and really do make it easy for operators to design mission-critical backbone networks. They offer mean time between failure (MTBF) reliability figures into the hundreds-of-years and highly integrated yet modular designs, which make expansion very straightforward. Before deciding on a trunking microwave radio, consider if the system:

  • Allows easy migration from TDM to IP with a minimal amount of replacement materials
  • Can expand to an expected maximum channel capacity (for example, six channels) without needing additional racks, etc.
  • Enables repeater configurations within one rack
  • Has a field-proven heritage of reliability and performance

Terry Ross
Senior Product Manager
Aviat Networks

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4G Upgrade Path Drives Backhaul Migration in Kenya

Safaricom's Internet Broadband Dongle (with SI...

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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3 Models for Microwave Link Error Performance? Laine Explains

Dick Laine explains ITU-R models

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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RAN Capacity Optimization Through IPoTDM Microwave Transport

This brief white paper summarizes how an IP-over-TDM (IPoTDM) approach can facilitate microwave network evolution to all-IP, consolidate the transport and management of circuit- and packet-based wireless network services in a single physical RAN infrastructure, and allow operators to address CAPEX and OPEX cost challenges by leveraging existing TDM transport resources to the maximum extent possible.

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