Long Term Fair Scheduling in a Cognitive Wireless Network with Spectrum Underlay

In this paper we study fair rate scheduling in an ad hoc cognitive wireless network with spectrum underlay. Transmissions in the network are allowed provided their interference to the primary network is below a predefined threshold. An optimal scheduling problem is formulated with an objective to achieve proportional fairness (PF) of the long-term average transmission rates among different links in the network. Two scheduling schemes are proposed for achieving PF of the average rates, each using different criteria to make scheduling decisions. Both scheduling schemes can be implemented distributively in the ad hoc cognitive network with limited assistance from the primary network. Our results show that the proposed PF scheduling schemes can achieve high overall throughput and close-to-optimum fairness.