Patent ID: 7542729
Filing Date: 2009-06-02
Classification: H03M,H04L,H04N

Abstract:
1. A signal transmission apparatus comprising: a modulator operable to modulate first carriers by a first data stream according to an m-level PSK or an m-level QAM to produce first modulated carriers, and modulate second carriers by a second data stream according to an n-level PSK or an n-level QAM to produce second modulated carriers, wherein adjacent two carriers of the first and second carriers are quadrate with each other, and wherein n is an integer greater than m; a converter operable to convert the first modulated carriers into a first OFDM symbol according to Orthogonal Frequency Division Multiplexing, and add a first guard interval to the first OFDM symbol to produce a first OFDM signal, and to convert the second modulated carriers into a second OFDM symbol according to Orthogonal Frequency Division Multiplexing, and add a second guard interval to the second OFM symbol to produce a second OFDM signal, wherein time periods of the first and second guard intervals are selectable; and a transmitter operable to transmit the first OFDM signal and the second OFDM signal.