Signal preprocessing based on gradient operators

There is a common belief that much of the licensed bands lies idle at any given time and location in wireless communications. In the case of high spectrum utilization, it is very vital to find out those spare bands for providing a better chance of opportunistic access in spectrum scarcity environment. In this paper, a novel algorithm based on gradient operators is proposed, which will be used to preprocess signals in wireless networks before detecting those spare bands quickly. After converting signal spectrum to two-dimension gray-scale image, it is time to apply the gradient operator to preprocess the wireless signals. Simulation results prove the practicality of the new algorithm as it can effectively reduce the impact of noise on the signal.