Abstract
The concept of a virtual contention window for assessment of temporal and probabilistic characteristics of the processes occurring in the wireless LAN 802.11 is considered. The relations for determining the transmission time delay of the data package, the uneven of transmission time, throughput of wireless channel, the probability of packet loss for networks with saturated load are proposed in this paper.
Highlights
The wireless local area networks (WLAN) of 802.11 standard are widely use for privet nets on the one hand and corporative nets with large number of users on the other hand.If we shall analyze the development of 802.11 standard during a time, we shall see different changes on physical and channel levels (802.11 a, b, g, n), which was done in order to improve some characteristics of local wireless telecommunication systems
Virtual Contention Window as a parameter VCW is a stochastic parameter of unplanned wireless network standard 802.11 (BSS), which is numerically equal to the averaged number of elementary time intervals during which the backoff counter provides a delay interval after transmitting the previous frame before transmitting the data frame of one station
Based on the analysis of the process of collisions, the ratios of (2) – (5), we can conclude that with the increase in the number of active stations in the network divergence values of collision probability during the various attempts to transmit a frame of information will decrease. This phenomenon is due to the fact that in addition to those stations that have experienced conflict during the transmission data frame within a virtual contention window all other stations will transmit at the first stage and will use some numbers with CW1 range to load the delay counter
Summary
The wireless local area networks (WLAN) of 802.11 standard are widely use for privet nets on the one hand and corporative nets with large number of users on the other hand. There we can see the most of models proposed for wireless network description It possible to estimate the accuracy of different models and it’s convenience on practice. Some of this models [1] give us a general description of probable events on 802.11 wireless networks by using of integral expressions. Because W may be equal to 8, 16 or 32 corresponding with different specifications of 802.11 standard, the calculated meaning of successful transmitting will be significantly less «one» Such result take place because formula (1) was proposed for estimation of Электроника и связь 6’ 2011 successful transmitting probability for process, which has begun during some elementary time slot. Due to considered problems and some other problems many scientists make their efforts in order to improve approaches for wireless networks performance estimation
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