VoIP over IEEE 802.11 wireless local area network (WLAN) is growing very fast and is providing a cost effective alternative for voice communications. WLANs were initially set up to handle bursty nonreal time type of data traffic. Therefore, the wireless access protocols initially defined are not suitable for voice traffic. Subsequently, updates in the standard have been made to provision for QoS requirements of data, especially the real time traffic of the type voice and video. Despite these updates, however, transmitting voice traffic over WLAN does not utilize the available bandwidth (BW) efficiently, and the number of simultaneous calls supported in practice is significantly lower than what the BW figures would suggest. Several modifications have been proposed to improve the call capacity, and recently isochronous coordination function (ICF) was introduced to mitigate the problem of low call capacity. In this paper, we propose a modified ICF which further improves the performance in terms of the call capacity. The proposed scheme uses multiplexing and multicasting in the downlink to substantially increase the call capacity.
Herbal medicines have been commonly used for the treatment and prevention of disease, health promotion and for the enhancement of the life span. The Curcuma species viz., C. Roxb., C. longa Linn and C. amada are used as medicine in traditional therapeutic practices. The remedy for various diseases including cough, diabetes and hepatic disorders. The efficiency of turmeric fractions, such as petroleum ether, chloroform, benzene, methanol and aqueous were evaluated for their inhibitory effect on clinical and standard strains of pathogenic bacteria. The methanolic fraction of Curcuma longa rhizome had high potential to inhibit some pathogenic bacteria i.e. S. aureus to a greater degree than other fractions of Curcuma longa. In our study the results show that the different fractions (petroleum ether, methanol etc.) of Curcuma caesia rhizome were more effective antimicrobial agents than the crude extract of Curcuma longa. The bacteria isolates include E. coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424), and Staphylococcus aureus (MTCC96) Antimicrobial activities were estimated by Disc diffusion method. The results were pointed as the methanol, acetone and petroleum ether, extract was more effective on all three pathogenic bacteria.
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