Providing Variable TXOP for IEEE 802.11e HCCA Real-Time Networks
Quality of Service (QoS) provided by the IEEE 802.11e amendment and by the proposed HCF Controlled Channel Access (HCCA) reference scheduler is tailored for Constant Bit Rate traffic streams. Moreover the numerous alternative scheduling algorithms are not suitable to serve Variable Bit Rate (VBR) traffic streams with the required QoS and real-time guarantees. This paper presents Immediate Dynamic TXOP HCCA (IDTH), a new scheduling algorithm based on a bandwidth reclaiming mechanism suitable to cooperate with a HCCA real-time scheduler. IDTH recovers the portion of the transmission time unused by the scheduled stations to provide a further capacity for the next variable bit rate traffic streams.