TCP Congestion Control Characteristics and Their Impacts in QoS over Mobile Broadband Networks

One of TCP's key task is to react and avoid network congestion episodes which normally arise in packet switched networks. A wide literature is existed in many different scenarios concerning the behaviour of congestion control algorithms and several congestion control algorithms have been proposed in order to improve performances. WLAN links have already been studied extensively in the literature. In this paper we focus on Mobile Broadband (MBB) networks that are in use today. We used NorNet Edge node which is connected to 3 different 3g ISP's (UMTS and CDMA2000). We also use three different TCP congestion control algorithms: TCP NewReno, TCP CUBIC as loss-based algorithms and TCP Vegas as delay based algorithms and try to see the impact of each TCP congestion control algorithm on the QoS characteristics. In the other word, we want to see how each MBB provider could affect the same TCP connection with same characteristics. We present QoS characteristics (e.g. Godput, delay) and discuss our observations. Our results could be used later for improvements in multi-path congestion controls