Channel adaptive power allocation and pilot optimization for OFDM systems

An adaptive resource allocation scheme is designed for OFDM that maximizes the average transmission rate by adapting the power of the data symbols while optimizing the pilot symbol spacing and power. Assuming imperfect channel state information (CSI) at the transmitter, the exact solution obtained for optimum power loading across data subcarriers can not be expressed in terms of elementary functions. A useful approximation, that has the simple form of a water-filling function, is derived for determining the optimum power loading function that is based on imperfect CSI. The merits of the proposed adaptive resource allocation schemes are corroborated by numerical results.