Transmission of SBC Speech via 16-Level QAM

The transmission of 16 kb/s sub-band coded (SBC) speech via Reed-Solomon (RS) coding and 16-level QAM modulation over Rayleigh fading channel is addressed. An average locking AGC method is described, which requires no side-information to be transmitted. Different RS coders were used to code the SBC bits depending on their perceptual significance and their position in the Gray coded QAM words. Proposed schemes operating at 5.3 and 6.7 kbaus yielded near toll quality speech for channel SNRs in excess of 29 and 22 dB, and delays of 180 and 144mm, respectively, for vehicular speeds of 30 and 60mph