Improved 3-dB Subgroup based Algorithm for Optimal Discrete Bit-Loading

Aggressive trends in higher throughput and QoS demands along with the increasing constraints on resources-at- hand (available bandwidth, peak emission power, processing delay etc.) require efficient and fast algorithms for resource allocation with no compromise in performance. For more than a decade, huge amount of research-work has been dedicated to improve the convergence time of discrete bit-loading algorithms for optimal allocation of bits to different sub-carriers of a multi- carrier system with respect to the channel response. Recently we proposed by Mahmood, A. and Jaffrot, E., (2006) the 3-dB Subgroup based allocation methodology which gives us the first insight into an underlying pattern of allocation, based upon which an algorithm can be devised for optimal discrete bit allocation using the Gap approximation factor for practical systems. In this work, we reduce further the complexity incurred by the 3-dB subgroup algorithm with no compromise on performance. The exact number of execution cycles of our improved algorithm over a simple scalar processor is compared to that of a recently proposed by Papandreou, N. and Antonakopoulos, T., (2005) algorithm for optimal discrete bit-loading to verify the fast convergence of our algorithm.