A simulation-based study of TCP dynamics over HFC networks

New broadband access technologies such as Hybrid Fiber Coaxial (HFC) are likely to provide fast and cost e ective support to a variety of applications including Video on Demand (VoD), inter-active computer games, and internet-type applications such as Web browsing, ftp, email, and telephony. Since most of these applications, use TCP as the transport layer protocol, the key to their eÆciency largely depends on TCP protocol performance. We investigate the performance of TCP in terms of e ective throughput in an HFC network environment using di erent load conditions and network bu er sizes. We nd that TCP experiences low throughput as a result of the well known problem of ACK compression. An algorithm that controls ACK spacing is introduced to improve TCP performance.