Data rate increasing method using multiple PN sequences for the superposed PNs on broadcasting system signals

For some additional data rate keeping backward compatibility, PN sequences can be good candidates. Because a PN sequence can be detected relatively with a small magnitude in low signal to noise ratio, it is advantageous to reduce their influences on the existing system signal. Conventionally PN sequences can be used to transmit modulation parameters for a hierarchically modulated T-DMB system and TxID information in ATSC 8-VSB digital TV. In this paper, we propose a method to increase data rates by mapping PN sequences to order-n QAM constellations. Thus each PN sequence transmits the same number of bits with order-n QAM modulation. Therefore, the data rates obtained by PN sequence mapping can be increased very much compared with the conventional PN sequence detection method.