Tau-AIMD for Asynchronous Receiver Feedback

In this work we first describe an asynchronous-feedback model which corresponds to the diverse roundtrip times (RTTs) of competing flows within the same communication channel. We show that even when the feedback of the receivers/network is asynchronous, the duration of a congestion epoch represents ‘common knowledge’ for the competing flows. Based on this property, we propose a diverse linear increase scheme in proportion to the RTT of each flow and we adjust periodically the windows of the competing flows accordingly, in order to enhance fairness of asynchronous-feedback environments. We name this scheme tAIMD and show that fairness of flows in asynchronous systems is improved since the increase-rate diversity of long and short RTT flows is largely canceled. We use the max–min notion of fairness to show that t-AIMD can constitute the foundation for other window-based, end-to-end algorithms that target a good balance between efficiency and fairness. Copyright # 2004 John Wiley & Sons, Ltd.