The feature of WiMAX most responsible for its speed, says Ding, is something called OFDMA, or orthogonal frequency-division multiple access. It’s a way of transmitting digital wireless signals that allows a base station to split a chunk of radio spectrum into multiple subchannels. By varying the number of channels assigned to each user and the power of those channels, OFDMA ensures a good connection everywhere, regardless of where the nearest base station is or how many buildings are nearby reflecting signals. “This dynamic quality of service is much less sensitive to overload and cell size,” says Ding.
Sprint’s competition, however, will catch up soon enough. Last year, Verizon and AT&T announced plans to upgrade existing 3G networks to an enhanced version of today’s 3G technology called LTE, or long-term evolution, and this technology is already being tested in selected cities. Ding says that Verizon estimates that LTE will be in service by the first half of 2011.
Operators face some tough decisions about how much to invest in building up new networks, since it’s hard to know how many new subscribers will be drawn in by the new technology to pay for the capital costs of infrastructure. “The iPhone phenomenon may be a good hint,” Ding says. Giving access to highly desirable mobile services can motivate people to switch carriers in large numbers, a phenomenon that the EVO’s backers hope to emulate.
True 4G phones by ITU standards will be a little longer in coming. The ITU is currently considering improved versions of both LTE and WiMAX as candidates for its specification for the next generation of wireless links, but that process isn’t expected to be complete until the end of this year at least, making the true heirs to today’s wireless a few years off.