ST-XCP: A Stable XCP Protocol

XCP is one of the most commonly used protocols in modern congestion control implementations. XCP can provide the available transmission rate to applications. It is well known fact that one of the issues of XCP is that the time-delay of its traditional implementation (TR-XCP) is twice the time-delay of its flow model. This leads to unstable behaviors when controlling the congestion in networks with heterogeneous propagation delays. This paper proposes an improvement of TR-XCP called the stable XCP (ST-XCP). ST-XCP decreases the control interval of XCP implementations and brings the behavior of the congestion control system back to the stability region. It is demonstrated in this paper, theoretically and through simulations, that ST-XCP outperforms TR-XCP as far as the queue size is concerned, and that it is also stable even while controlling the congestion in networks with heterogeneous propagation delays.