Analytical TCP throughput model for high-speed downlink packet access

This study deals with the throughput analysis of data services over high-speed downlink packet access (HSDPA) systems. The achievable throughput is calculated with an approximate analytical method based on the Padhye model that has two input parameters: the packet loss probability and the transmission control protocol (TCP) round trip time. The proposed solution is to calculate these parameters with an equivalent queuing network model of the HSDPA system that takes into account the possible congestion points in the system and the protocol layers that have dominant impact on the delay and packet drop. The modelling considerations and the analysis method are described in detail. Finally, the model is validated with a performance study of the HSDPA system that is executed with detailed NS2-based simulations too. The proposed method is found to be reasonably accurate requiring less computational effort than the simulations.