Broadband One Networks plans to introduce a wireless data service in September that would give high-speed Internet access to laptop-toting businesspeople roaming miles away from the nearest antenna. Broadband One, a San Diego startup, will introduce the service in Bozeman, Montana, a college town tucked away in the south-central part of the state. If the service does well there, the company plans to offer the service in other parts of the country. JC