HSDPA Flow Control and Congestion Control

The flow control and congestion control are the key TNL features which have been developed to enhance the overall end-to-end performance for the downlink of the HSPA network. The motivation and theoretical aspects of flow control are described in this section. A new adaptive credit-based flow control algorithm is introduced for HSDPA. This enhanced flow control scheme has been implemented, tested and validated using the detailed HSPA simulator. Comprehensive simulation results and analysis of the flow control are presented in this chapter. Since the flow control scheme itself cannot avoid congestion in the transport network, a new congestion control concept has been introduced combined with the adaptive flow control scheme. First the concept of congestion control is described in detail and next, the different variants of congestion control algorithms are presented that have been implemented, tested and validated within the HSPA simulator for the downlink.