Comcast offers new broadband

Comcast Corp. plans to become the first major cable TV operator to roll out wireless broadband service outside of Wi-Fi hot spots.

The Philadelphia-based company said it would launch the service today in Portland, Ore., with at least three other cities -- Philadelphia, Atlanta and Chicago -- to follow this year.

The service, which uses WiMax technology, offers speeds of up to 4 megabits per second, faster than any comparable non-Wi-Fi service being marketed. It is intended for use with laptops but not other mobile devices.

The service will rely on the WiMax network of Clearwire Corp., a joint venture of cable operators, including Comcast, and technology companies. Customers will have a choice of buying only local service, or national service that switches between Clearwire’s network where available and Sprint Nextel Corp.’s data network.

Phone companies have lined up behind a competing technology called LTE, which Verizon Communications Inc. plans to deploy next year.