Adaptive Wavelet Modulation with Unequal Power Allocation for DSA Networks

Nowadays, the spread of wireless applications has led to the need of new spectrum resources and to the need to exploit in a more dynamic and efficient way those already in use. Several recent research works have confirmed the presence of unused spectrum portions in the range 30 MHz-3 GHz. As a consequence, developing new techniques to assure the utilization of these unused resources has become a key issue for telecommunications engineers. Wavelet Modulation has some characteristic that makes it suitable to exploit channel opportunities avoiding interferences with the primary users of the spectrum. In this paper we propose an Adaptive Wavelet Modulation with Unequal power allocation. Unequal power allocation is performed according to both channel availability and data sensitivity to channel errors: zero power (i.e., carrier suppression) is assigned to potentially harmful wavelets whereas the power budget is distributed on safe wavelets in order to optimize the minimum square error between transmitted and received data. Genetic Algorithms have been used to solve the optimization problem of the weights.