Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article A Heuristic Optimal Discrete Bit Allocation Algorithm for Margin Maximization in DMT Systems | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 12140 7 pages doi 2007 12140 Research Article A Heuristic Optimal Discrete Bit Allocation Algorithm for Margin Maximization in DMT Systems Li-Ping Zhu 1 Yan Yao 1 Shi-Dong Zhou 1 and Shi-Wei Dong2 1 Department of Electronic Engineering School of Information Science and Technology Tsinghua University Beijing 100084 China 2 National Key Laboratory of Space Microwave Technology Xi an Institute of Space Radio Technology Xi an 710100 China Received 14 July 2006 Revised 24 December 2006 Accepted 25 December 2006 Recommended by Erchin Serpedin A heuristic optimal discrete bit allocation algorithm is proposed for solving the margin maximization problem in discrete multitone DMT systems. Starting from an initial equal power assignment bit distribution the proposed algorithm employs a multistaged bit rate allocation scheme to meet the target rate. If the total bit rate is far from the target rate a multiple-bits loading procedure is used to obtain a bit allocation close to the target rate. When close to the target rate a parallel bit-loading procedure is used to achieve the target rate and this is computationally more efficient than conventional greedy bit-loading algorithm. Finally the target bit rate distribution is checked if it is efficient then it is also the optimal solution else optimal bit distribution can be obtained only by few bit swaps. Simulation results using the standard asymmetric digital subscriber line ADSL test loops show that the proposed algorithm is efficient for practical DMT transmissions. Copyright 2007 Li-Ping Zhu et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Discrete multitone DMT is a modulation technique that has been widely used in various digital .
