  Noise is the major problem while working with wireless LAN. In this paper we
analyze the noise by using active receiving antenna and also propose the
detection mechanism based on RF energy duration. The standard back off
mechanism of 802.11 wireless LAN (WLAN) increases the contention window when a
transmission failure occurs in order to alleviate contentions in a WLAN. In
addition, many proposed schemes for 802.11 WLAN behave adaptively to
transmission failures. Transmission failures in WLANs occur mostly by two
causes: collision and channel noise. However, in 802.11 WLAN, a station cannot
know the cause of a transmission failure, thus the adaptive schemes assume the
ideal situation in which all transmission failures occur by only one of two
causes. For this reason, they may behave erroneously in a real world where
transmission failures occur by both causes. In this paper, we propose a novel
scheme to detect collision, which utilizes transmission time information and RF
energy duration on the channel. By detecting collisions, a station can
differentiate the causes of transmission failures and the adaptive schemes can
operate correctly by using the detection information.
