A Delay Optimal Scheduling Policy for Real Time Services in WCDMA Systems

Enhanced Uplink operation of WCDMA-UMTS systems utilizes fast Node B scheduling and a short Transmission Time Interval (TTI) of 2ms. The scheduling decisions are based on Scheduling Information (SI) sent from each User Equipment (UE) to the Node B. The weakness of the existing scheduling framework is that the SI does not include information regarding the delay sensitivity of each traffic flow, as well as the actual delay that the buffered data have experienced, especially for real-time services. In this paper, we propose the inclusion of such information in SI by introducing modifications into the respective 3GPP specifications. Thus, we propose a Delay Aware Channel Prioritization (DACP) criterion optimized for real-time services. Furthermore, we propose a DACP-based packet Scheduler (DACP-S)which is able to dynamicallymanage the EnhancedDedicated Channel’s (E-DCH) transmissions and offer Quality of Service differentiation. The performance of the proposed scheme is evaluated by means of system level simulations.