We consider the decentralized multi-armed bandit problem with distinct arms for each players. Each player can pick one arm at each time instant and can get a random reward from an unknown distribution with an unknown mean. The arms give different rewards to different players. If more than one player select the same arm, everyone gets a zero reward. There is no dedicated control channel for communication or coordination among the user. We propose an online learning algorithm called dUCB4 which

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... hieves a near-O(log 2 T ). The motivation comes from opportunistic spectrum access by multiple secondary users in cognitive radio networks wherein they must pick among various wireless channels that look different to different users.