Carriers’ plans to introduce 4G wireless at a glance

The state of 4G wireless at a glance

This is a summary of how U.S. wireless carriers are dealing with the transition to fourth-generation, or 4G, network technology, which promises faster data speeds:

— Sprint Nextel Corp. subsidiary Clearwire Corp. already has a 4G network up and running, and Sprint started selling the first compatible phone this summer. But Clearwire is using WiMax, a technology that’s imcompatible with LTE, which everyone else is using or plans to use.

— Verizon Wireless plans to bring LTE to 25 to 30 cities later this year, mainly for PC modems. Phones will come next year.

— AT&T Inc. plans to launch commercial LTE service in the middle of next year. In the meantime, it’s upgrading the speeds on its 3G network.

— T-Mobile USA hasn’t made any specific plans public. It’s focusing on upgrading its 3G network for now.

— LightSquared is a dark-horse entrant funded by a private equity firm. It plans to build an independent LTE network, with service starting next year, but financial and regulatory hurdles remain.

— MetroPCS Communications Inc. turned on LTE in Las Vegas on Tuesday, and plans to expand it to the rest of its coverage area by January.