Adversarial Multi-user Bandits for Uncoordinated Spectrum Access

An adversarial multi-user multi-armed bandit framework is used to develop algorithms for uncoordinated spectrum access. It is assumed that the number of users is unknown, and that users receive zero reward on collision. The users do not coordinate with each other, and an adversary chooses different rewards for different users on the same channel. The proposed algorithm combines the Exp3.P algorithm developed in prior work for single user adversarial bandits with a collision resolution mechanism to achieve sub-linear regret. It is shown that if every user employs the proposed algorithm, the system wide regret is of the order Oleft( {Tfrac{3}{4}} right) over a horizon of time T. The algorithm is then extended to the dynamic case where the number of users in the system evolves over time, and it is shown to lead to sub-linear regret.