Tropos Picocells take on WiMax Macrocells

At CTIA 2007 this week, Tropos Networks unveiled its Next Generation product, the MetroMesh NG, which can integrate radios for Wi-Fi, 4.9GHz and WiMax. The company calls it “the world’s first meshed multi-protocol picocell system.”

“We’ve looked at a lot of architectures, what people are doing, and the macrocellular architecture used by WiMax and EV-DO — taking the footprint of existing cellular towers and putting what they call broadband on it — it’s interesting,” says Saar Gillai, vice president of engineering and product management. “But it has challenges.”

“We’re making the case strongly that mobile WiMax needs dense cell deployment, 20 or more per square mile,” adds Bert Williams, vice president of marketing at Tropos. “The macrocell architecture used today is useful for point-to-multipoint, but has issues with true symmetrical bandwidth that Web 2.0 needs.”

The point of the MetroMesh NG is to bring the Tropos software solutions such as policy-based Spectrum and Application Based Routing Engine (SABRE) to more than just Wi-Fi for end users and 4.9GHz for public safety, by virtualizing services to support other radios.

Tropos says that 20 MetroMesh nodes in a one square mile area, using 2GHz or higher bands, will offer the same performance as straight WiMax — 1Mbps on more than 90% of clients. The NG could have wired backhaul or use WiMax, while the mesh connections between nodes continues to run on Wi-Fi.

Coinciding with this announcement, Tropos said it is working with WiMax equipment maker Redline Communications to ensure that their products are interoperable. Redline’s proprietary RedCONNEX products, such as the new 5.4GHz AN-80i subscriber unit just approved by the Federal Communications Commission (FCC), will be able to work with any MetroMesh node to provide backhaul. The plan is to also make the RedMAX line of WiMax products work with MetroMesh. The Redline equipment can get juice from a Power over Ethernet (PoE) connection coming directly from a MetroMesh box mounted on the same pole.

Gillai says Tropos will someday support the 802.16j WiMax Mesh specification — more specifically, “Multihop Relay Specification” — which is currently in its very early stages with the IEEE. “There’s a lot of discussion on how that would work,” he says. “It’s not the most efficient use of spectrum — but we’ll have it.”

As mobile WiMax connections become available in client systems, Tropos plans to add the capability to connect via WiMax to MetroMesh. “The last step will be to add WiMax to the mesh itself, to increase capacity as needed,” says Williams. For now, “the emphasis [regarding WiMax] will be on backhaul — capacity injections,” he says. “The weak link is almost always the client connection.”

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