Home // International Journal On Advances in Telecommunications, volume 2, number 4, 2009 // View article
Authors:
Liaoyuan Zeng
Sean McGrath
Eduardo Cano
Keywords: Ultra Wideband; Multiband Orthogonal Frequency Division Multiplexing; Bit Error Rate; Cognitive Radio.
Abstract:
A novel dynamic power and bit allocation scheme for spectral efficiency maximization in the Cognitive Ultra Wideband radio system is presented in this paper. A new bit error rate expression is derived based on approximating a sum of independent log-normal random variables as a single log-normal random variable using the Fenton-Wilkinson method in order to analyze the spectral efficiency in the UWB multipath channel. A series of M-ary quadrature amplitude modulation zones can be generated over each UWB subcarrier by manipulating the BER expression. The total transmitted power is optimally distributed among the UWB subcarriers for the use of those zones with a maximum M on each subcarrier. The power and bit allocation is divided into primary allocation and advanced allocation for efficient implementation. The performance of the dynamic allocation algorithm is analyzed over different UWB fading channels. The results show that the spectral efficiency of the system is significantly improved by an optimal power and bit allocation techniques.
Pages: 121 to 130
Copyright: Copyright (c) to authors, 2009. Used with permission.
Publication date: March 17, 2010
Published in: journal
ISSN: 1942-2601