Empirical investigation on the dependence of TCP upstream throughput on SNR in an IEEE802.11b WLAN system

An empirical investigation on the dependence of TCP upstream throughput against signal to noise ratio (SNR) in an IEEE802.11b WLAN system was carried out in various environments and varieties of QoS traffic. The TCP upstream throughput (TCP_upT) was measured for various SNR observed. An Infrastructure based IEEE802.11b WLAN system having networked computers on which measurement software were installed, was set up consecutively in various environments (open corridor, small offices with block walls and plaster boards and free space). Empirical models describing the TCP_upT against SNR for different signals ranges (all ranges of signals, strong signals only, grey signals only and weak signals only) were statistically generated and validated. Our results show a strong dependence of TCP_upT on the received SNR which varied as the SNR values changed from high (strong signals) through low (grey signals) to very low (weak signals). Our models showed lower RMS errors when compared with other similar models. We observed RMS errors of 0.5431955Mbps, 0.447938789Mbps, 1.04536603Mbps and 0.4503096Mbps for all SNR model, strong signals model, Grey signals model and Weak signals model respectively. Our models will provide researchers and WLAN systems users with a tool to estimate TCP_upT in a real network in various environments by monitoring the SNR.