| Popis: |
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. |
