摘要 |
Methods and apparatus of using a licensed spectrum to transmit data when an unlicensed spectrum is congested are disclosed. The method includes 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 has been received by the first mobile device 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. |