Modeling Channel Access Delay and Jitter of IEEE 802.11 DCF

Abstract

With the ever-increasing requirement of WLAN to support real-time services, it is becoming important to study the delay properties of WLAN protocols. This paper constructs a new model to analyze the channel access delay and delay jitter of IEEE 802.11 DCF in saturation traffic condition. Based on this analytical model, average channel access delay and delay jitter are derived for both basic access and RTS/CTS-based access scheme. The accuracy of the analytical model is validated by simulations and furthermore we discuss the impact of initial contention window, maximal backoff stage, and packet size on channel access delay and delay jitter of 802.11 DCF using the proposed model.

Deriving the Suspended Backoff Counter Value Distribution in CSMA/CA

“…Therefore, (13) It is important to note that for each variate w of W', P{F < w | W' = w} represents the sum of (w − 1) component probability terms P F (f) | W' = w , one for each variate f of F satisfying the condition f < w. For example, P{F < w | W' = 3} is the sum of P F (1) | W'=3 and P F (2) | W'=3 . Furthermore, since the event of a non-transmitting node having its counter suspended is independent of the event of it selecting a particular variate of W', all the component probability terms of P{F < w | W' = w} are equal regardless of the value of w. As such, the following equation relating P F (f) for the 1st type of suspended backoff samples to the component probability P F (f) | W'=w, w>f is valid: (14) Since the probability of suspensions in this case is equivalent to the sum of all the component probabilities across all possible values of f and w restricted to the condition f < w, we get the following expression relating it to the component probability: (15) Eliminating the component probability term from Eqs. …”

A comprehensive DCF performance analysis in noisy industrial wireless networks

“…Most of the models have extended the Bianchi's model to account for other parameters and situations, such as nonsaturated traffic and finite buffer size , finite retransmission attempts , error‐prone channel , channel capture , hidden terminal , and improving the accuracy of the model in predicting performance metrics by considering backoff freezing and so on . From a traffic point of view, most papers assume the saturation condition; each node always has a packet waiting to be transmitted . This can be considered as the worst‐case scenario that simplifies the network analysis and also results in an upper (lower) bound estimation about the normal/noncongested situation of the network delay (throughput).…”

The Idle Period Distribution for CSMA/CA Networks for Spectrum Sensing Applications

“…In [5] and [6] done by Foh et al and Hu et al, respectively, this shortcoming was addressed independently. Building on the results of these early works, two more characteristicstransmission delay and delay jitter -were derived in [7] by Chatzimisios et al,in [8] by Li et al,and in [9] by T. Sakurai and Hai L. Vu.…”

“…Taking this into consideration, and incorporating Eqs. (7,8), we finalize the expression for P F (f) thus:…”