Exalt Communications Specializes in Backhaul

Campbell, Calif.-based Exalt Communications is an unusual wireless equipment manufacturer. The company specializes in point-to-point (PtP) microwave backhaul. Mark Davis, Exalt’s senior director of product marketing, says that the company, founded in 2004, has last mover advantage, incorporating the latest innovations in software-defined radios and signal processing technology into its products.

The company addresses a market it sees as worth about $8 billion per year worldwide, of which $7 billion is backhaul for mobile (cellular) operators. “Exalt is one of a very few companies to compete in all of these markets: mobile, enterprise, and service provider,” he says.

With a common platform for all its products, the company has been able to release over 30 microwave radios since its first, which hit the market in the middle of 2006.

Exalt delivers only carrier-class products, Davis says. That means delivering guaranteed throughput and carrying Ethernet and TDM protocols natively. “A lot of products have specialized in either TDM or Ethernet,” he says. “TDM-based products carried Ethernet over TDM and Ethernet-based products carried TDM over Ethernet. There can be significant overhead and latency costs with those approaches.”

Exalt chose to introduce us to Sparkplug, a venture-backed company that has acquired other WISPs, notably Prairie i-net.

“Our primary focus is taking Ethernet-delivered services for business and leveraging microwave technologies,” says Ben Brimhall, vice president of engineering and network operations. Brimhall himself founded the WISP Verde Communications and in mid-2007 sold it to Sparkplug.

Because it has acquired several WISPs in different states, it has a patchwork rather than a contiguous network, but the strategy is to be local to every city it serves. Big city markets include Chicago, Nashville, Phoenix, and Las Vegas, says Brimhall.

If you acquire a WISP, you may find you need to upgrade the equipment it has. Case in point, says Brimhall, Prairie i-net. “That network had leveraged Western Multiplex Equipment that was dated now. Six or seven years ago, 10 Mbps capacity was good, but it’s not what we need now. Now, we need 50 Mbps to 100 Mbps. One advantage with Exalt is that we could put in the equipment without replacing cabling and antennas. It fit right into the network configuration we had in place.”

Add new equipment, and you gain services-oriented features. With Exalt, that means the capability to handle VLAN tags.

Like many WISPs, Sparkplug uses 5 GHz for backhaul and 2.4 GHz for service to the customer. For higher capacity or more crowded areas, it uses 6 GHz, 11 GHz, 18 GHz, and 23 GHz. The company also owns some LMDS spectrum (28 GHz and 29 GHz).

GPS Sync

Another key feature is GPS Sync. Davis says that when you’re using Time Division Duplex (instead of Frequency Division Duplex), you want co-located to send at one time and receive at another. If some are transmitting while others are receiving, you will generate self-interference.

Attach a GPS kit to your tower or rooftop installation, and link up the radios you’re using, and you can use the time stamp on the GPS signal to co-ordinate transmission and reception. An internal sync approach can be used, as well, without the need for GPS.

Being able to increase the amount of equipment you can put on one site, says Brimhall, helps the bottom line. Popular sites are using up available equipment and spectrum. “Our business is a fixed-cost model,” he notes. “If we can put more gear and more customers on a tower, that improves the economics. It allows us to better leverage our footprint.”

Another differentiator, says Davis, is that Exalt always discloses the actual user throughput of its radios. “Many Wi-Fi-based radios present the over-the-air data rate, which typically the 54 Mbps associated with 802.11a/g, and not the actual user throughput, which is only on the order of 25 Mbps to 30 Mbps.”

The result, he adds, is that with his company’s radios, you get the throughput you’re expecting.

The future

Davis notes that his company has released 30 radios in about two years, and has plans to release many more. It will expand will coverage of both licensed and license-exempt spectrum and will expand the number of different configurations (wholly outdoor radios, wholly indoor radios, and radios with an indoor component and an outdoor unit (ODU)) available at each frequency.

The company is moving, with the wireless industry, from Fast Ethernet (100 Mbps) to Gigabit Ethernet (1 Gbps) and has already begun adding data network features such as 802.1p and 802.1q (VLAN trunking).

Article courtesy of ISP-Planet.

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