“Improving TCP Performance over Wireless Networks” Mahendra Singh #1 Pankaj Kumar Goyal #2 Shrey Parashar #3 SIIT Jaipur BMIT-Jaipur SIIT-Jaipur mahendra1188@gmail.com pankajgoyal2000@gmail.com shreypositivesideofworld@yahoo.in ABSTRACT:- Reliable transport protocols such as TCP are tuned to perform well in traditional networks where packet losses occur mostly because of congestion. However, networks with wireless and other lossy links also suffer from significant non-congestion-related losses due to reasons such as bit errors and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in degraded end-to-end performance in wireless and lossy systems. In this paper, we compare several schemes designed to improve the performance of TCP in such networks. These schemes are classified into three broad categories: end-toend protocols, where the sender is aware of the wireless link; link-layer protocols, that provide local reliability; and split-connection protocols,that break the end-to-end connection into two parts at the base station. We present the results of several experiments performed in both LAN and WAN environments, using throughput and good put as the metrics for comparison. Our results show that a reliable link-layer protocol with some knowledge of TCP provides very good performance. Furthermore, it is possible to achieve good performance without splitting the end-to-end connection at the base station. We also demonstrate that selective acknowledgments and explicit loss notifications result in significant performance improvements. INTRODUCTION:- TCP/IP is a set of protocols developed to allow cooperating computers to share resources across a network. It was developed by a community of researchers centered around the ARPAnet. Certainly the ARPAnet is the best- known TCP/IP network. However as of June, 87, at least 130 different vendors had products that support TCP/IP, and thousands of networks of all kinds use it. First some basic definitions. The most accurate name for the set of protocols we are describing is the "Internet protocol suite". TCP and IP are two of the protocols in this suite. (They will be described below.) Because TCP and IP are the best known of the protocols, it has become common to use the term TCP/IP or IP/TCP to refer to the whole family. It is probably not worth fighting this habit. However this can lead to some oddities. For example, I find myself talking about NFS as being based on TCP/IP, even though it doesn't use TCP at all. (It does use IP. But it uses an alternative protocol, UDP, instead of TCP. All of this alphabet soup will be unscrambled in the following pages.)