TCP/IP is the main and most widely used transport protocol for reliable communication. Actual use of TCP/IP protocol on wireless links in the Internet has found some serious performance issues. Different versions of the TCP have been planned to improve the performance of data transmission. Due to its widespread need, researchers have been proposing and studying new various TCP variants trying to improve its behavior. Different variants of TCP named TAHOE, RENO, New RENO, compound TCP, TCP Vegas, HS (High Speed) TCP, etc.