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DragonWave's Smaller, Better Radio

Kanata, Ontario-based DragonWave is announcing a new product line, the Horizon Compact radio. The company has always claimed a manufacturing advantage in the market for high end backhaul radios, at 23 GHz and higher spectrum because it is able to build many radio variants off a single platform, making its radios better and cheaper.

Click to view larger imageThe design of the Horizon Compact  is another case of better and cheaper, similar to the effect of Moore's Law on the PC industry. The design of this new outdoor radio puts everything in one box, reducing cabling and streamlining the delivery of traffic.

Savings come from a variety of sources, including reduced latency and the reduced cost of mounting the unit on leased towers.

The company's earlier outdoor model, the AirPair, has a modem component and a radio component. Combining the two provides savings to WISPs. "Let's say I'm paying $200 per month per widget that I place on the tower," says Alan Solheim, DragonWave vice president of product management and business development. "If I can get rid of one widget, I save $200 per month, which adds up to thousands of dollars over the life of the unit."

In addition, he claims, the more efficient design provides greater reliability. "The mean time between failures of the new unit is almost twice the combined MTBF of the two units it replaces," he says. "That means higher network availability and it also means fewer truck rolls and fewer spares kept in storage."

Solheim says that efficiencies are increased with DragonWave's network performance monitoring, which enables remote monitoring through any of a wide variety of standard protocols. "We can find which unit is at fault. We avoid that situation where the craftsman in the field is replacing things until the link works again. A good percentage of the few units we get back from the field are 'no fault found.'"

"It's not just smaller and cheaper; it's also faster and better," says Solheim. Two radios can achieve up to 800 Mbps throughput (using different polarizations), depending on the amount of spectrum available per channel (see chart below).

Click to view entire chart
Modulation and link budget, partial chart (click to view entire chart)

The unit requires no air conditioning, Solheim says. What about Death Valley? "The radio is rated for -40 celsuis to 50 celsius," he says. "If you were in Death Valley, we could add a sun shield, which typically gives you an extra 15 degrees of operating margin. We have radios in Phoenix and Dubai and a bunch of hot places."

The small unit handles wind well too. Specifications have it operating in winds up to 70 Mph and surviving winds up to 125 Mph.

Latency within the small unit is also reduced, rising as high as 0.4 ms under worst case conditions, but typically running at 0.1 ms.

Pair your radios

The radio has two connectors. The second connector can be used to daisy chain two radios together. Alternatively, the second input can be used for out of band monitoring (in which case, Solheim says, you'll have a switch nearby which can shape traffic between two radios).

A pair of radios can also be designed to provide network redundancy. The WISP can either operate both radios, but have a stronger TOS for a portion of the bandwidth, or one of the two radios can be on standby. "Failover takes 50 ms to 100 ms and is therefore transparent to applications," says Solheim.

"The modem is defined in firmware, not in an ASIC," says Solheim. That means it can be upgraded with a download.

"We designed a better modem," says Solheim, "one that's more tolerant to phase noise. That means the unit can achieve higher modulation, with the resulting throughput achievements shown in the chart above.

The radio has an all-IP core. Wouldn't all WISPs use data packets? Solheim points out that providers such as TowerStream that offer T-1 replacement need to be TDM-compatible.

In the 23 GHz to 28 GHz spectrum, there's no interference, since links are narrowband point to point, Solheim notes. However, there is some rain fade. When it occurs, the radio can step down the modulation, increasing the link budget by up to 15 db (again, see the chart above for the details on how stepping down modulation improves the link budget).

The Horizon Compact radio will be available from DragonWave in North America in April and from its channel partners worldwide at the same time.

The product is sold with all features available, unlockable through an additional purchase (see Upgradable Radio Promises Cheaper Point of Entry). A 100 Mbps link would cost $15,000 (but the provider could later upgrade to a faster throughput, if necessary.

Article courtesy of ISP-Planet.