Performance of VoIP and Mixed Traffic over HSPA

Abstract:
VoIP is expected to become an increasingly important service type in the packet domain, and may on the longer term even replace circuit-switched speech services in future mobile network generations. High Speed Downlink Packet Access (HSDPA) and Enhanced uplink Dedicated Channel (E-DCH) are regarded as the preferred transmission mode for Wideband Code Division Multiple Access (WCDMA) packet data, promising improved system capacity and link performance. This paper provides performance values for pure VoIP and mixed traffic services over HSPA (High Speed Packet Access). Major problems of voice data transmission over data bearers are the inherent small packet sizes for VoIP together with strong packet delay requirements. For this purpose, system level simulations are configured to consider HSPA features as well as Quality of Service (QoS) aware scheduling functionalities. It was found that a scheduler with a packet aggregation feature can increase the VoIP performance in the DL. Additionally it is shown that the applied scheduler concept is able to provide a common serving of VoIP and Hypertext Transfer Protocol (http) data. In the UL simulations it becomes obvious that a pure VoIP capacity is limited by the noise rise (NR). Furthermore it is shown that it is possible to serve real time and non-real time users even if they have different scheduling approaches.