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Only a fourth of the world’s cell sites are connected via fiber, and the vast majority of those are in Asia, according to Heavy Reading. For the remaining three-fourths — or whatever percentage of that wireless service providers would like to upgrade to Ethernet backhaul — meshed microwave can be a good option.
According to the white paper “Deploying Mobile Backhaul – Ethernet Microwave Technology Choices for Lower OPEX” by Tzvika Naveh, solutions marketing manager at Ceragon Networks Ltd. (CRNT), microwave already is the preferred backhaul technology by most mobile operators worldwide, and outside the United States, nearly 70 percent of backhaul traffic travels over microwave links.
Now, through the magic of Ethernet, microwave is becoming an even more attractive option for wireless backhaul.
“Mobile and fixed wireless services are reaching more and more areas of the world, and, as they do, backhaul is emerging as a common source of bottlenecks,” said Michael Kennedy, president with Network Strategy Partners. “Wireless Carrier Ethernet provides a simple and cost efficient solution to this problem.”
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The combination of Ethernet switching and microwave connectivity can help mobile operators realize a reduction in connections and gear that can add up to between 45 and 55 percent in savings, said Taylor Salman, the solutions marketing director in charge of wireless backhaul at Ciena Corp. (CIEN).
Traditional backhaul systems are based on TDM, which is a hierarchical system that employs a tree architecture. One of the drawbacks of a tree architecture is that in order to get redundancy, the network operator must establish dual links between every hop. By comparison, with packet-based systems, especially those with traffic engineering, the network operator can set up primary and secondary paths.
Partial mesh is one architecture a carrier can use for that, and it’s less expensive than tree. Between a fully redundant tree and partial mesh with the same level of redundancy the carrier can reduce by 30 to 40 percent the number of connections in the network.
By pairing this mesh architecture and Ethernet technology in microwave portions of network, the network operator also can realize savings in terms of provisioning, gear and real estate. For example, Salman explained, if a system has four microwave units, it also must have four indoor units; but by putting an Ethernet switch in the microwave network, those four indoor microwave units are replaced with a single Ethernet switch.
And the benefits don’t end there. In an April column on Internet Evolution, Patrick Donegan, senior analyst at Heavy Reading, writes: “Many operators with cellular networks are also looking at new generations of Ethernet microwave, and many of these report seeing excellent performance from this technology in the labs. Vodafone, for example, estimates the capacity enhancement of Ethernet microwave at anywhere from three to five times today's TDM microwave solutions, within the same microwave spectrum allocation.”
Still, Ethernet-based microwave mesh is a fairly new concept, and microwave gear that can take advantage of Ethernet switching just recently have become available, according to Salman. While Ciena doesn’t sell microwave gear (it has partners that do that), what it does bring to the table for this application is the Ethernet switching technology including the highly important traffic engineering component, he continued.
Other Ethernet vendors have forged similar partnerships with microwave outfits. For example, Greg Gum, vice president of marketing and business development at ANDA Networks Inc. recently told xchange it has a partnership with BridgeWave Communications Inc., with which Ethernet gear provider RAD Data Communications Ltd. also has a relationship.
Other companies attacking the wireless backhaul opportunity with gigE microwave products and services include DragonWave Inc., FiberTower Corp. (FTWR), GigaBeam Corp. (GGBM.PK), Harris Corp. (HRS), Nextlink Wireless (a subsidiary of XO Holdings), and Tower Cloud Inc..
In addition to fiber- and microwave-based methods of Ethernet backhaul, copper-based Ethernet backhaul is another option being offered up by various vendors. Salman said that while that can be a decent short-term solution, its appeal is limited.
“All operators want fiber, but not if it’s too costly or it’s too hard to pull it to the fiber. Microwave tends to be the second choice, because it provides the next largest step of bandwidth — microwave can be up to 800mbps, but usually is more around 400mbps, for a link between two towers,” said Salman.
“Ethernet over copper provides mid-band rates — in the tens of megabits per second. This is going to be for towers where there’s not a whole lot of data growth expected, but they want to pull that system onto the Ethernet network for cost savings anyway. But it’s not a long-term solution,” said Salman. “It’s really a temporary solution until the more advanced solutions roll out, typically.”
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