Clearwire has expanded its WiMAX network into three additional markets: Boston, Daytona Beach, Fla., and Providence, R.I. Sprint, which offers 4G service on Clearwire’s network, also launched services in those markets.

The company’s Boston launch is of significance because it is the hometown of Sprint 4G President Matt Carter.

“We are proud to be the leader in the race to 4G,” Carter said in a statement. “In particular, it’s rewarding to deliver 4G service to Boston – my hometown.”

The announcement from Sprint and Clearwire coincided with news from T-Mobile USA that it had completed HSPA+ upgrades in nine new markets, including Boston and San Diego.

T-Mobile USA network chief Neville Ray said in a statement that the company’s HSPA+ expansion was on pace to cover more than 200 million people this year.

T-Mobile markets its HSPA+ network as offering 4G speeds, although HSPA+ technically a 3G technology. The carrier claims its HSPA+ network offers peak theoretical speeds of 21 Mbps and will offer 42 Mbps theoretical speeds in 2011. Real-life speeds will be considerably slower than theoretical speeds.

Clearwire says its network offers real-life speeds averaging 3 Mbps to 6 Mbps with bursts over 10 mbps on the downlink. Clearwire based its figures on average download user speeds during live network tests.