A Two-Stage Spectrum Assignment Scheme for Power and QoS Constrained Cognitive CSMA/CA Networks

Opportunistic spectrum access is a key technology for the development of novel applications with stringent QoS requirements on top of wireless sensor networks. However, the many challenges posed by opportunistic spectrum access itself are further exacerbated by the power constrained nature of wireless sensors and the QoS requirements of the applications to be supported. In this work we consider the problem of dynamic spectrum assignment in the context of cognitive CSMA/CA based wireless sensor networks. We propose a two-stage dynamic spectrum assignment scheme that exhibits minimal power consumption and guarantees the QoS requirements of data flows in the network. The proposed scheme utilizes both opportunistic and free access bands via cognitive radio technology and is based on a two-stage stochastic integer program with recourse. Numerical results verify the effectiveness of the proposed dynamic spectrum assignment scheme.