Clearwire is launching its 4G WiMax network in New York, San Francisco and Los Angeles before the end of the year. The service offers speeds similar to WiFi but without the short range limitations and is already available in 56 markets across the US.

The upcoming launch will strengthen the network's reach into America's largest cities and will likely make the service more attractive to business users who are often on the road. New York will be get service from November 1, Los Angeles on December 1, and San Francisco in late December, the company said.

Services will be launched by Clearwire under its "Clear" brand and by Sprint, which owns a majority stake in Clearwire. In New York service will also be offered by Time Warner Cable and in San Francisco by Comcast.

Networks in the three cities have been under test for several weeks and last month PC World reported on initial service in San Francisco. The magazine found download speeds of almost 3Mbps and upload speeds of 1Mbps on the test network. When full service begins users should see download speeds of between 3Mbps and 6Mbps, PC World said.

Clearwire also said it plans to launch 4G service in Denver, Miami, Cincinnati and Cleveland before the end of 2010. The additional launches means Phoenix will become the largest US city without 4G service from Clearwire/Sprint.