TCP was mainly developed considering assumption of wired network, ignoring the properties of wireless transmission. Wireless transmission links are highly unreliable causing loss of packets all the time. The proper approach to dealing with lost packets is to send them again, and as quickly as possible. This paper aims at studying the effects of unidirectional and bidirectional networks on various TCP variants. The effect of application of SNOOP and ECN on the performance enhancement of TCP along with TCP variants is assessed, improving the performance of TCP over wireless network by implementing cross layer design protocol (Snoop). ECN is used to avoid congestion and Snoop aims at retransmitting the lost