Sculpting Radio Waves

TenXc Wireless is turning RF into an art form. Its tool of choice is the technology of adaptive spatial processing, and the company works strictly on the cell sector beams that form the final link between cell phone and cell tower. The engineers are essentially sculpting radio waves, forming a transmission path of the cell's signals in a 33° cell sector into an oddly heart-shaped design that ultimately will save their carrier customers gobs of spectrum.

TenXc is in the spectral efficiency business — shoving as many bits into a hertz of spectrum as possible. The problem is that as carriers hit their capacity limits, they are usually forced to choose between two very distasteful scenarios: either buy more spectrum or start splitting cells, said Ross Ernst, vice president of marketing for the company. Both alternatives require capital investment, and that investment is more than likely going to be steep because capacity crunches most often occur in urban markets where the cost of spectrum is higher and deploying a new cell site is all the more difficult. Spectrum acquisition can present other inefficiencies, considering capacity problems often occur in specific clusters, not across the entire geographical breadth of a spectral license.

“If you have to go back to the market to get more spectrum, it takes a lot of dollars,” Ernst said. “Building a new site is not only costly, it's slow and painful.

But TenXc claims that its beam-sculpting techniques present a third alternative, one that requires upgrades at the cell site but ultimately would give a PCS tower an 80% improvement in spectral efficiency at a cost 80% less than deploying a new cell site, said Thomas Ginter, vice president of product line management. It isn't a compression technology or a mere tweak in the transmission technology, he said. The TenXc bi-sector array is actively going out and grabbing the unused capacity at the dead-zone fringes of the cell sector, creating a cross-polarized spectral swathe that conforms much more closely to the triangular wedge of a call sector. This kind of beam forming not only grabs unused capacity, it also minimizes the overlap between sectors, resulting in a 30% per-sector capacity improvement, Ginter said.

Probably one of its biggest advantages, though, is that the technology can be deployed on an as-needed basis. Instead of buying up spectrum across an entire market or deploying a new cell tower, the infrastructure can be installed on a sector-by-sector basis. A carrier needs only to replace a single 65° antenna with the TenXc array, Ernst said, the RF sculptor will do the rest.