Line of sight wireless without a license.
One of the technology's key benefits is the amount of data that can be transmitted over short distances: The Merrill Lynch link transmitted data at a rate of 1 Gbps, nearly 1,000 times faster than a typical broadband connection. The lack of bureaucracy is another plus -- there are no spectrum licenses to buy. There are also no cables to lay, making installation cheap and simple relative to the potential connection speeds.