IP Telephony over Satellite Networks: Control of the Playout Delay to Maximize the Perceived Quality

In streaming applications, playout buffering is operated at the receiver side to compensate network delay variations. This function allows the receiver to reduce packet lateness at the expenses of an increase in the end-to-end delay. IP Telephony is one of the applications where this function is crucial since transmission delays heavily affect the interactivity and significant losses injure the signal quality. Many approaches have been proposed in the last decade to control the playout delay in IP Telephony, where the most recent ones rely on the use of the ITU-T E-Model to evaluate the quality perceived by the end-user. However, none of these specifically deals with the scenario where the service is provided over satellite networks. Indeed, nowadays, this scenario is quite frequent with the reduction of the costs of the satellite channels and equipments. In this case, there are some specific issues that need to be dealt with to improve the effectiveness of the playout control algorithms. These issues are related to the delays that are encountered when satellite links are involved. These aspects are described in this paper, which also presents a new quality-based playout algorithm that provides better results with respect to alternative approached when satellite transmissions are involved.