A cross-layer flow control algorithm over HSDPA networks

High Speed Downlink Packet Access (HSDPA) employed in 3G networks considerably augments wireless bandwidth, which enables a variety of mobile services based on TCP. However, the fundamental assumptions of TCP are disrupted by the properties hold by wireless network, such as high bit error rate, large delay and drastic bandwidth oscillation, which lead to the consequences of spurious time outs, spurious retransmission, and sending rate lagging behind the variation of bandwidth, degrading the wireless utilization greatly. To solve the problem, we design a cross-layer flow control algorithm which based on the bandwidth information of the current network environment and calculate a reference value to adjust the sending rate of the multiple senders. The experimental results show that the wireless bandwidth resource is sufficiently utilized, the queue length is stable and the sending rate is insensitive to the round trip time when using this algorithm.