A Cyclic-Executive-Based QoS Guarantee over USB

Universal Serial Bus (USB) is a popular standard for PC peripheral devices because of its versatile peripheral interconnection specifications. USB not only provides simplified hardware connectors but also supports for various bus traffics, such as isochronous and bulk transfer activities. Although the USB specifications provide a way for users to specify the upper bound on the number of bytes for each data transfer in a 1ms time frame, little work is done to provide QoS guarantees for devices (e.g., the lower bound on the bytes for each device type in a 1ms time frame) and a mechanism in enforcing the guarantees. In this paper, we propose a cyclic-executive-based bandwidth reservation and scheduling method to support QoS guarantees over USB, especially for those isochronous bus activities. The proposed bandwidth reservation and scheduling method could reserve USB bandwidth for devices in an ondemand fashion. The capability of the proposed scheme was shown by the implementation and demonstration of a USBbased surveillance system prototype which adopted the pro-