Dynamic and fair spectrum access for autonomous communications

Most of existing wireless systems are regulated by a fixed spectrum assignment strategy. This policy leads to an undesirable situation that some systems may only use the allocated spectrum to a limited extent while others have very serious spectrum insufficiency situation. Dynamic spectrum access (DSA) is emerging as a promising technology to address the above issue such that the unused licensed spectrum can be opportunistically accessed by the unlicensed users. To enable DSA, the unlicensed user shall have the capability of detecting the unoccupied spectrum, controlling its spectrum access in an adaptive manner, and coexisting with other unlicensed users automatically. In this chapter, we will give an overview on the DSA for sharing open spectrum. And we investigate a radio system transmission opportunity (TXOP)-based spectrum access control protocol, with the aim of improving spectrum access fairness and ensure safe coexistence of multiple unlicensed radio systems. Simulation is carried out to evaluate the TXOP-based scheme with respect to spectrum utilization, fairness, and scalability.