Patent ID: 8259828

Claim:
A method of aligning sub-carriers of radio signals adapted for transmission over two adjacent frequency channels in a wireless orthogonal frequency division multiplexing (OFDM) system, wherein the method comprises: aligning a first plurality of sub-carriers of a first radio signal and a second plurality of sub-carriers of a second radio signal within an overlapped frequency region in-between the two adjacent frequency channels by shifting a center frequency of the first radio signal with a frequency offset, wherein the first radio signal and the second radio signal are adapted for transmission over the two adjacent frequency channels, wherein a first frequency channel is one of the two adjacent frequency channels, and wherein the wireless OFDM system process data transmission over multiple radio carriers in different frequency channels at the same time and each frequency channel comprises a pre-defined center frequency, wherein shifting the center frequency of the first radio signal is according to a first pre-defined center frequency of the first frequency channel, and wherein the shifted center frequency of the first radio signal is different from the first pre-defined center frequency of the first radio signal.