JOINT DESIGN OF A CHANNEL-OPTIMIZED QUANTIZER AND MULTICARRIER MODULATION

We present an algorithm for design of a joint source-channel coder usi ng a channel-optimized quantizer and multicarrier modulation, By chang ing the power of each subchannel in the multicarrier modulation system , different degrees of error protection can be provided for different bits according to their importance. The algorithm converges to a local ly optimum system design. Compared to a Lloyd-Max scalar quantizer or a LEG vector quantizer using single-channel transmission, our optimize d code can yield substantial performance improvements. The performance improvements are most pronounced at low channel signal-to-noise ratio s.