Stochastic Model Based Opportunistic Channel Access in Dynamic Spectrum Access Networks

We present a stochastic model-based opportunistic channel access and transmission scheme for cognitive radio enabled secondary users for single data channel. We refer to this scheme as Residual Idle Time Distribution based Scheme (RIBS). In this scheme, the SU randomly senses the channel and if the channel is sensed idle, then it uses residual idle time distribution to estimate its transmission duration such that the probability of its interference with PU is below a predefined threshold. We derive analytical formulae for various performance metrics of SU and validate them through simulations. Simulation experiments are conducted for two different scenarios. In the first scenario, we use synthetically generated channel occupancy data due to PU transmissions using two standard distributions (2-phase Erlang and Uniform distribution). In the second scenario, we use data collected by simulating a TDMA-based PU network that runs realistic applications (VoIP and Web browsing). A pair of sender and receiver SU uses RIBS to opportunistically transmit on the channel. Our simulation experiments show that SU can use RIBS to opportunistically transmit on the channel without violating the interference probability constraint. We also list some of the challenges in using RIBS in realistic scenarios, and provide a comprehensive methodology to use RIBS in such scenarios.