A Practical Method for Improving Delay Performance of Time Slot Allocation in DVB-RCS

In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay performance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (VBR). From the proposed models, it is found that the time slot location plays a leading role in affecting the traffic delay performance, which ameliorates more when the time slot location is more uniform in frame. Compared with the traditional mode of consecutive time slot allocation, the mode of uniform time slot allocation can effectually reduce the average delay and jitter, which will not vary with the frame length. Furthermore, with the mode of uniform time slot allocation increasing bandwidth assignment could promote the delay performance more effectually. This article also puts forward a practical time slot uniform allocation method (TUAM), which is based on the DVB-RCS standard and compatible with it. The computer simulation, apart from testifying to the validity of the model, shows that it leads to efficacious reduction of the mean traffic delay and jitter. By adopting the method, the real-time traffic-like voice over IP (VoIP) trafficʹs packets will not suffer from dropping due to an overlong end-to-end delay, thus improving quality of service (QoS) provision for real-time traffics in DVB-RCS systems.