Effect of Flat Fading in 802.11 MAC for Cross Layer Evaluation Using Channel Emulator

WLAN 802.11 operating in 2,4 GHz are being intensely implanted mainly in public environments. In these environments mobility is always a present characteristic. The objective of this work is to analyze the behavior of 802.11 MAC with flat fading. To reach this objective an emulation system was developed to create the flat fading channel phenomenon. With a WLAN and the emulator was possible to show the cross layer effect, evaluating the WLAN performance analyzes in mobility conditions. The experiments evaluated: rate of transmission in each modulation level, data rate in the transport layer, network efficiency, jitter and throughput. The network information was obtained through SNMP. The results show that the 802.11 MAC had problems to support services that need high performance, as VoIP and Streaming. Therefore when the receiver is in movement the degradation does not allow the quality required by these types of services.