Ciena in the Clear
Ciena says that its kit is deployed in Las Vegas -- due to be officially launched there today -- as well as for earlier launches in Atlanta, Baltimore, and Portland, Ore. Clearwire is using Ciena’s LE-311v service delivery switches, CN 5305 service Aggregation Switches, and Ethernet Services Manager software for its backhaul system. The Kirkland, Wash.-based operator is using a mixture of microwave and fiber for the system and then using Ciena's switches to centralize traffic. "Clearwire uses microwave to the tower, but further in they have fiber as well," says a Ciena spokesperson in an email.
"Ciena’s Carrier Ethernet platforms are at the towers (LE-311v) and aggregation sites (CN 5305) and provide the backhaul," the official adds. "Clearwire is able to provision an end-to-end Carrier Ethernet circuit across both microwave and fiber portions of the network using Ciena’s equipment and software (Ethernet Services Manager)."
Clearwire has to use microwave and fiber links, rather than the more common T1 lines typically used by cellular carriers, because it needs more horsepower connecting high-speed WiMax basestations to the wired IP network. Sprint Corp. (NYSE: S) was tripped up by this when it originally tried to deploy the XOHM network in Baltimore with copper, but found that performance at the basestation was sluggish because of a backhaul bottleneck. (See Sprint's Backhaul Bottleneck.)
Clearwire typically uses the microwave links in licensed 18 GHz and 24 GHz bands, as well as some unlicensed 5.8 Ghz backhaul. The 5.8 Ghz is still relatively free from interference, according to company CTO, John Saw.
Clearwire has said that using microwaves can actually make its backhaul network cheaper than standing systems. The carrier, however, has always said that it will use fiber when the price is right. (See Clearwire's Backhaul Bet.) — Dan Jones, Site Editor, Unstrung