Tropos Plans Better Client Communication

By Eric Griffith

July 13, 2006

Connections to Wi-Fi devices like laptops have been the weakest link for Tropos mesh networks, but the company says a new software engine provides the fix.

Tropos Networks — the headline-grabbing mesh networking equipment maker with 300 deployments and counting — knows that the biggest complaint it gets from customers is that client devices (laptops, PDAs and more) just can't connect to the mesh network.

"Even if throughput is low, it's often linked to poor connectivity," says Ellen Kirk, the company's vice president of marketing. "Metro Wi-Fi networks that don't compensate for widely variable clients can't get predictable connections. You need that for customer satisfaction."

"There's no such thing as a standard Wi-Fi client," she says. "'Standards compliant,' maybe, but not standard. Power varies, and some are even engineered to hang onto a router or access point even though the connection quality is bad." On the free Wi-Fi network Tropos powers in New Orleans, which has lots of transient clients considering the city's post-Hurricane Katrina status, she says they've seen as many as 750 different client types connect in a 24-hour period.

Since subscribers/users don't really know the differences about types of clients — "we can't train users," says Kirk, adding, "though sometimes we train them to stand by the window to get a better signal" — that means making a change to the network itself to get better connections.

Tropos' solution is new software for its MetroMesh routers called the Adaptive Mesh Connectivity Engine (AMCE). It compensates for unique clients by adjusting per-packet transmission power and timing control to get stronger signals to and from low-powered client devices.

"Our equipment is relatively high-powered routers," says Kirk, "and clients can hear them better than the routers hear the clients." AMCE mitigates outside interference to improve packet reception and, thus, throughput. In effect, it changes how the network looks to the client, without requiring anything to be installed on the laptop, PDA or other Wi-Fi device.

In May, Tropos announced Tropos Metro Compatible Extensions (TMCX), software that would be installed on equipment they call a wireless modem — the mesh network equivalent of a cable modem —inside a building, to provide better connections with the outside. AMCE, on the other hand, works with all clients. The biggest benefit would be gained through a combination of TMCX and AMCE on a Tropos-powered mesh network.

Part of what brought Tropos to the decision to enhance the client connections were reports it got from its provider customers. Many of these were generated by Tropos Insight, its data analysis module. As AMCE ships, so will new client reports for Insight so providers can "see client performance down to the client level," says Kirk. "Network operators need this to manage a network of tens or hundreds of thousands of users." With it, providers can examine how many users are active, what kinds of client systems they're using to connect, bandwidth they're using, where they go when roaming on an integrated map, etc. The reports can show users that may be connecting to multiple routers, which could reveal a "hopping" problem as the client tries to find a steady signal — a problem AMCE could impact.

Phil Belanger, managing director of Novarum, a new wireless consultancy, says this is a positive feature. However, "there's nothing mesh about it," he says, because there's a distinction between the backhaul mesh connecting all the network nodes, and the client connections that come from those same nodes.

"The client access network has no mesh on it at all — if it did, the clients wouldn't work," Belanger says. "The naming [of AMCE] is awkward, as it has nothing to do with the mesh." He says it will have no impact on the total number of nodes Tropos will have to provide per square mile to get coverage in a metropolitan deployment.

That said, Belanger believes any network, mesh or not, can benefit from having this technology for client connections. He compares it directly to radio resource management features already found on controller-based WLAN architectures from companies like Cisco Systems. Its also similar to the work being done toward an 802.11k standard by the IEEE, under the name Radio Resource Measurements.

The benefits of this technology will go beyond just happier end users. "When a higher percentage [of clients] can go faster, that benefits the whole network," says Belanger. "The traffic gets on and off more quickly. This is an overall help."

AMCE will be rolled out in phases, the first of which is already available as a free download to MetroMesh customers. It's already running on the citywide Wi-Fi network called Cyber Shot in St. Cloud, Florida.  Earlier this year, St. Cloud's network took a drubbing in an Associated Press story for not reaching all 28,000 residents of the Orlando suburb. However, in the Tropos announcement today, Jonathan Baltuch, president of MRI, is quoted as saying, "AMCE significantly improved the reliability of client connections in the St. Cloud network, enabling us to offer an outstanding user experience."

A second phase will include tighter controls for connecting clients — that won't come until later this year. It will also be free for MetroMesh customers.

Tropos equipment will power EarthLink's planned networks for Philadelphia, San Francisco and other cities; its hardware is already in place for the first phase of service run by EarthLink in Anaheim, California.

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