A Flexible Bit Allocation Algorithm Based on Adaptive Method for OFDM Channels

This paper presents a new bit and power allocation scheme for OFDM systems with low computational complexity in which the overall transmission power is minimized by constraining the fixed data rate and bit error rate. The algorithm and simulation include two stages. The first stage involves the application of a target BER and SNR of each sub-carrier for a variable-rate bit pre-allocation. The second stage applies greedy and Campello approach to achieve constant channel rate of bit allocation. In a word, bit allocation with constant rate performs variable rate bit allocation first, and then modifies the overall bits to a constant. The simulation results demonstrate that the scheme has significant computational advantages over the conventional algorithms while providing optimal performance. It also provides considerable universality and flexibility for both the fixed rate voice data and variable rate multimedia data of the broadband wireless communication.