An improved code modulation scheme with STBC for FM IBOC broadcasting

In-Band On-Channe (IBOC) digital audio broadcasting (DAB) is a method of digital audio radio , which could transmit analog FM and digital audio simultaneously. However, due to the existence of fading and interference in FM bands, transmit capacity has reached its limitations for the bandwidth, thus, adding digital transmission in the crowded FM band is a challenging proposition. Diversity is one of the key techniques for digital transmission. Space-time block code (STBC), the technique of temporal diversity, is applied to raise transmission reliability. Meanwhile, bit-interleaved coded modulation (BICM) can provide spatial diversity without occupying high bandwidth. Based on spatial and temporal diversity, a scheme that STBC is embedded into MIMO-BICM, can add the reliability and effectivity of transmission over fading channels. In this paper, a type of coded modulation scheme was proposed in Hybrid in-band on-channel system, by use of BICM-STBC instead of the convolutional code, and would get coding gains without bandwidth expansion. The simulation results show that the proposed scheme can effectively improve the receiving performance of an FM IBOC system over Rayleigh fading channels, with about 2dB coding gains when BER is below 10^-5.