WiMAX startups aim to boost radio speeds, network deployments

At WiMAX World this week, two startups launched products that foretell the next stage of WiMAX evolution: instead of chips, base stations or client equipment, these software products ride on top of WiMAX nets to improve performance or facilitate carrier services.

Israel-based Pallasium unveiled software originally developed to protect military wireless nets from jamming attacks. Running on standard WiMAX basestations, the Pallasium algorithm lets the radio take full advantage of the available spectrum. Pallasium says its algorithm can triple the capacity of existing WiMAX base stations without adding any additional hardware.

Another startup, Telsima, in Sunnyvale, Calif., has created a set of software modules that together form a complete mobile network architecture that runs on its line of WiMAX basestations and its own and third-party subscriber stations. Using these components, carriers can create mobile WiMAX services without the need for specialized gateways or a Mobile IP infrastructure.

Pallasium was launched in 2005 by its four founders who have experience in Israeli cellular providers and military communications. Their goal is to commercialize a technology called adaptive null steering.

WiMAX base stations have one radio and a trio of antennas (each with a power ampflier) that use the same swath of spectrum. To minimize interference between the antennas, operators have to subdivide the spectrum into three parts, assigning one to each antenna. Essentially, the base station can only use one-third of the spectrum’s capacity, says Yair Shapira, the company's vice president of business development, and for years an R&D engineer with Motorola, specializing in cellular wireless.

Adaptive null steering uses an antenna to generate signal that cancels out the signal from another antenna. Imagine a water wave coming at you. You “push” another wave toward it, with the same amplitude but the opposite phase. When the two waves meet, they “flatten” or cancel each other out.

What Pallasium introduced was the ability to do this interference cancellation not with additional separate antennas, but with the trio of existing antennas on the base station. In effect, each antenna no longer has to worry about interference from its neighbors. So it can now use the full “three-thirds” of its spectrum instead of just one-third. Base station manufacturers can triple capacity without adding any antennas or power amplifiers.

In future, “Wave 2” implementations of WiMAX will introduce multiple input multiple output (MIMO) which does use multiple antennas to boost input. The Pallasium software will be able to work with these base stations also. But in some cases, such as the upcoming 700MHz spectrum auction in the United States, radio physics may make MIMO impractical for this frequency. The Pallasium algorithm would let operators wring the most reuse out of their precious spectrum, according to Pallasium president Tzvi Shechori.

At WiMAX world this week, Pallasium demonstrated a simulation, based on WiMAX Forum guidelines, of the completed algorithm in action. And the company is working with a basestation maker, unnamed for now, to launch field trials by year-end.