Cross-Layer Backpressure to Improve HSDPA Performance

High speed downlink packet access (HSDPA) is providing increased user data rate by introducing additional functionalities at the Node B. To achieve optimal radio resource utilization HSDPA flow control is applied to control the amount of data sent from the radio network controller (RNC) to the Node B over the Iub transport network. HSDPA flow control is not taking into account the available transport resources which can lead to situations when HSDPA packets are dropped due to congestion. These drops are triggering Radio link control (RLC) protocol retransmissions that are decreasing the HSDPA performance. We propose a cross-layer backpressure in the RNC to prevent HSDPA packet drops at the transport; we consider the impact of this enhancement on the system performance and evaluate it with NS2 simulations