الفهرس 
Background of Multicarrier Communication SystemOnly 14 pages are availabe for public view
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Abstract
Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme is the optimum version of the multicarrier transmission scheme which has the capability to achieve high data rate transmission. The fundamental aspect in the design of single-user (SU) OFDM systems is allocation the resources (bits and power) over number of subcarriers. In Multi-User OFDM (MU-OFDM) systems, also called Orthogonal Frequency Division Multiple Access (OFDMA), a subset of subcarriers is assigned to different users. Allocating the resources (subcarriers, bits and power) to users sharing the channel is the key issue of MU-OFDM system. Therefore, the thesis presents an efficient and low complexity power allocation algorithm for SU OFDM systems at first, which is subcarrier gain-based power allocation (SGPA) algorithm. The proposed SGPA algorithm provides a nearly optimal performance in bit rate maximization and greatly reduces the computational complexity compared with the standard greedy power allocation (GPA) algorithm and the other suboptimal discrete bit loading schemes. Finally, the thesis introduces an efficient subcarrier-power allocation algorithm for MUOFDM system, in which the subcarrier-power allocation algorithm is divided into two stages which are subcarrier allocation stage and power allocation stage. The proposed subcarrier allocation algorithm aims to improve the fairness between users and enhance the system capacity. After that, the power allocation algorithm can be applied by using SGPA algorithm or GPA algorithm which is executed for loading the bits and power on the user’s subcarriers. The proposed subcarrier-power allocation algorithm achieves better performance in increasing total system capacity and improving the fairness between the users with slightly high computational complexity compared with other previous algorithms.