Patent ID: 8248947

Claim:
A method of using a licensed spectrum to transmit data when an unlicensed spectrum is congested, the method comprising: transmitting a first signal from a first mobile device to a second mobile device using an unlicensed spectrum; determining, at the first mobile device, whether a first response signal from the second mobile device has been received by the first mobile device using the unlicensed spectrum, wherein the second mobile device does not send the first response signal when the unlicensed spectrum is congested, and wherein the second mobile device determines that the unlicensed spectrum is congested when a third mobile device within a communication area of the second mobile device transmits a third signal using the unlicensed spectrum; and transmitting a second signal from the first mobile device to the second mobile device using a licensed spectrum when the first response signal has not been received by the first mobile device using the unlicensed spectrum.