On Power-Loading Algorithms for Packet-Access OFDM Systems

Numerous power-loading techniques for wireless applications have been proposed in the literature. However, most of the existing power-loading schemes may not always be suitable for packet-access orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we propose a Lagrange multiplier power-loading (LMPL) algorithm for packet-access OFDM systems with fixed modulation and coding transmission. The proposed LMPL algorithm offers a closed-form solution for the power-loading optimization problem under a total transmit power constraint. As a closed-form solution may not be available for adaptive modulation and coding (AMC) transmission, we use a low-complexity joint LMPL algorithm to enhance the system throughput. Numerical results show that the proposed LMPL algorithms outperform the traditional channel inversion power-loading (CIPL) scheme. It is also shown that the theoretically derived throughput very well matches the simulation results.