Dynamic spectrum assignment for white space devices with dynamic and heterogeneous bandwidth requirements

In this paper, a TV white space (TVWS) network in which there is a centralized spectrum manager (SM) is considered. The SM is connected to the geo-location database (GLDB) to periodically obtain the available spectrum fragments, and is responsible for assigning the available spectrum to the white space devices (WSDs) in its coverage region. The spectrum available is usually fragmented with different bandwidths, and the bandwidth required by the WSDs can also be diverse. Unlike existing works which assume complete knowledge of all WSDs´ bandwidth requirements before assignment, we consider the more practical settings that WSDs request bandwidth in a sequential manner. Upon the arrival of a bandwidth request, the SM has to determine which fragment the request should be assigned to, without a prior knowledge of the bandwidths of the future requests. We are interested in designing the spectrum assignment policy at the SM upon each arrival of bandwidth request. The above problem is formulated as a stochastic sequential decision-making problem. The optimal spectrum assignment policy to maximize the overall spectrum utilization of the TVWS network is computed through the value iteration method. We demonstrate the performance advantage of our proposed optimal spectrum assignment policy over two heuristic policies through numerical results. To the best knowledge of the authors, this is the first paper that addresses the modeling and design considering the sequential behaviors of WSDs for GLDB-based TVWS network.