TCP/IP is the de facto standard of the networking world. It dynamically adjusts routing of packets to accommodate the failures in channels and allows construction of very large networks with less central management. But, IP packets are based on the datagram model and are not really suited to real-time traffic. In order to overcome the drawbacks, a new network technology, ATM, is proposed. ATM provides Quality of Service (QOS) guarantee for various classes of application and in-order delivery of packets via connection oriented virtual circuit. Unfortunately, when ATM is to be internetworking with the existing network infrastructure, some special signaling, addressing and routing protocols are needed. IP over ATM is one of methods proposed by IETF. It allows existing TCP/IP applications to run on ATM end-stations and ATM networks to interconnect with existing LAN/WAN Technologies. But, the poor performance of TCP/IP over ATM leaves something to be desired. Partial Packet Discard (PPD) and Early Packet Discard (EPD) are two famous schemes to improve its performance.

This thesis proposes a "selective packet retransmission" scheme for improving HTTP/TCP performance when transmitting through ATM networks. In selective packet retransmission, we utilize the property of human's perception tolerance for errors to determine whether to retransmit a corrupted TCP segment or not. For lossable data, such as image, when error occurs because of cell lost, it will not be retransmitted. The simulations show that, for the same buffer size and traffics load, selective packet retransmission results in higher throughput than PPD, EPD, and plain TCP over ATM.