Asymptotic capacity of multicarrier transmission over a fading channel with feedback

We study the asymptotic capacity of multicarrier transmission through a frequency-selective fading channel with limited feedback. The rate at which the capacity increases is characterized as a function of the number of subchannels N for the uniform power distribution over an optimized subset of channels, and optimal water filling. For Rayleigh fading, we also consider a finite-precision rate control scheme and show that the O(log N) increase in data rate can be achieved with a feedback rate, which grows as O(log/sup 3/ N). If the number of active subchannels is bounded, then the capacity grows only as O(loglog N).