A novel co-existence algorithm for unlicensed variable power devices

In the unlicensed spectrum, any device is free to transmit without a license. Such a spectrum has significant benefits, but serious challenges must first be overcome. Foremost is the risk of drastic performance degradation due to a lack of incentive to conserve shared resources. Previous work has identified this problem for devices that transmit for longer duration than necessary. This paper demonstrates this problem for devices that always transmit at maximum power to maximize throughput. For devices that can vary transmission power, the problem is solved if devices reduce transmission power when received interference exceeds defined thresholds. We propose a co-existence algorithm to optimize system throughput when each of two such devices can transmit up to the maximum power allowed on a given channel. We show the device performance with current unlicensed band regulations is rarely optimal, and that the proposed algorithm is better.