The dependence of TCP downstream throughput (TCP down T) on signal to noise ratio (SNR) in an IEEE802.11b WLAN system was investigated in various environments and varieties of QoS traffic. TCP down T 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 TCP down T against SNR for different signal ranges (all ranges of signals, strong signals only, grey signals only and weak signals only) were statistically generated and validated. As the SNR values changed from high (strong signals) through low (grey signals) to very low (weak signals), our results show a strong dependence of TCP down T on the received SNR. Our models showed lower RMS errors when compared with other similar models. We observed RMS errors of 0.6734791 Mbps, 0.472209 Mbps, 0.9111563 Mbps and 0.5764460 Mbps for general (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 the TCP downstream throughput in a real network in various environments by monitoring the received SNR. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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 up T) 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 up T 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 up T 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 up T in a real network in various environments by monitoring the SNR.

An empirical investigation on the dependence of TCP upstream throughput (TCPupT) against signal to noise ratio (SNR) in an IEEE802.11b WLAN system was carried out in various environments and varieties of QoS traffic using an Infrastructure based IEEE802.11b WLAN system set up consecutively in various environments (open corridor, small offices with block walls or plaster boards and free space). Empirical models describing the TCPupT against SNR for different signal ranges (all signals, strong signals, grey signals and weak signals) were developed and validated for both single and multiple users on the network. Our results show a strong dependence of TCPupT 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 they and other similar models were compared with validation data. We observed RMS errors of 0.5605471Mbps, 0.4479389Mbps, 1.04536603Mbps and 0.5813471Mbps for the General, Strong signals, Grey signals and Weak signals models respectively for the single user scenario. We also observed RMS errors of 1.3319396Mbps, 0.9457431Mbps, 0.8092979Mbps and 0.4220292Mbps for the multiple users scenario. An appreciable difference was observed between the throughput behavior for single and multiple users on the network showing the inefficiency of the distributed coordination function and Point coordination function used in WLANs as access mechanisms. Our models will provide researchers and WLAN systems users with a tool to estimate the TCP upstream throughput in a real network in various environments by monitoring the SNR.

This paper presents the performance analysis of a quarter-wave monopole antenna radiating at a frequency of 2.4 GHz. Two antenna models were proposed. The whip monopole antenna (WMA) at length l-equal to λ / 4 , and the improved whip monopole antenna (IWMA) at a length slightly less than λ / 4 . To get the IWMA, the length of the antenna was gradually reduced by a factor of 0.25 mm until the optimum length of the antenna was achieved. The antennas were modelled and analyzed using a 3D electromagnetic solver known as HFSS. Simulation results show that the IWMA has excellent performance over the WMA. The WMA resonated at 2.3 GHz, with a reflection coefficient of -12.36 dB, a VSWR of 1.65, an impedance bandwidth of 2.17–2.47 GHz and a gain of 5.9 dB. But by slightly reducing the length of the monopole antenna, the IWMA resonated at 2.4 GHz. The reflection coefficient of the IWMA was 1.99 dB better than the WMA. The IWMA had a wider impedance bandwidth than the WMA. It was only in the antenna gain that the WMA was better. The IWMA can function as a tyre pressure monitoring system (TPMS) antenna because it is compact and have excellent antenna parameters.