A queueing model for HTTP traffic over IEEE 802.11 WLANs

Miorandi, Daniele; Kherani, Arzad A.; Altman, Eitan

doi:10.1016/j.comnet.2005.04.004

Cited by 55 publications

(51 citation statements)

References 23 publications

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“…Before concluding this review of related work, it is useful to notice that alternative approaches have been proposed to model the interactions of TCP with the IEEE 802.11 MAC protocol. A simpler analysis is conducted in [33], where the statistics of the number of stations with nonempty buffers are obtained by assuming that they follow a Bernoulli distribution law.…”

Section: Related Workmentioning

confidence: 99%

“…However, this is not seen as a limitation because previous work [13] and the outcomes of our experiments show that packet losses may be negligible in high-speed WLANs with a limited channel interference. In addition, many of our modeling assumptions are commonly adopted in previous papers [30], [32], [33] on analyzing the TCP dynamics in 802.11 WLANs.…”

Section: Modeling Assumptionsmentioning

confidence: 99%

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Throughput Analysis and Measurements in IEEE 802.11 WLANs with TCP and UDP Traffic Flows

Bruno

Conti

Gregori

2008

IEEE Trans. on Mobile Comput.

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Abstract-There is a vast literature on the throughput analysis of the IEEE 802.11 media access control (MAC) protocol. However, very little has been done on investigating the interplay between the collision avoidance mechanisms of the 802.11 MAC protocol and the dynamics of upper layer transport protocols. In this paper, we tackle this issue from an analytical, simulative, and experimental perspective. Specifically, we develop Markov chain models to compute the distribution of the number of active stations in an 802.11 wireless local area network (WLAN) when long-lived Transmission Control Protocol (TCP) connections compete with finite-load User Datagram Protocol (UDP) flows. By embedding these distributions in the MAC protocol modeling, we derive approximate but accurate expressions of the TCP and UDP throughput. We validate the model accuracy through performance tests carried out in a real WLAN for a wide range of configurations. Our analytical model and the supporting experimental outcomes show that 1) the total TCP throughput is basically independent of the number of open TCP connections and the aggregate TCP traffic can be equivalently modeled as two saturated flows and 2) in the saturated regime, n UDP flows obtain about n times the aggregate throughput achieved by the TCP flows, which is independent of the overall number of persistent TCP connections.

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Section: Related Workmentioning

confidence: 99%

Section: Modeling Assumptionsmentioning

confidence: 99%

Throughput Analysis and Measurements in IEEE 802.11 WLANs with TCP and UDP Traffic Flows

Bruno

Conti

Gregori

2008

IEEE Trans. on Mobile Comput.

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“…Hence the number of STAs that are active with a high probability is insensitive to N for large N . See also [4], [18]. Hence with the above observations and assumptions, S k is modeled as a Markov chain, over all nonnegative integers.…”

Section: The Mathematical Model and Its Analysismentioning

confidence: 99%

Analytical models for capacity estimation of IEEE 802.11 WLANs using DCF for internet applications

et al. 2007

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Abstract-We provide analytical models for capacity evaluation of an infrastructure IEEE 802.11 based network carrying TCP controlled file downloads or full-duplex packet telephone calls. In each case the analytical models utilize the attempt probabilities from a well known fixed-point based saturation analysis. For TCP controlled file downloads, following [3], we model the number of wireless stations (STAs) with ACKs as a Markov renewal process embedded at packet success instants. In our work, analysis of the evolution between the embedded instants is done by using saturation analysis to provide state dependent attempt probabilities. We show that in spite of its simplicity, our model works well, by comparing various simulated quantities, such as collision probability, with values predicted from our model. Next we consider N constant bit rate VoIP calls terminating at N STAs. We model the number of STAs that have an uplink voice packet as a Markov renewal process embedded at so called channel slot boundaries. Analysis of the evolution over a channel slot is done using saturation analysis as before. We find that again the AP is the bottleneck, and the system can support (in the sense of a bound on the probability of delay exceeding a given value) a number of calls less than that at which the arrival rate into the AP exceeds the average service rate applied to the AP. Finally, we extend the analytical model for VoIP calls to determine the call capacity of an 802.11b WLAN in a situation where VoIP calls originate from two different types of coders. We consider N1 calls originating from Type 1 codecs and N2 calls originating from Type 2 codecs. For G711 and G729 voice coders, we show that the analytical model again provides accurate results in comparison with simulations.Index Terms-TCP throughput on WLAN, VoIP on WLAN, capacity of WLAN, performance modeling of DCF.

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“…Then we need to find the AP service rate (μ) In table 1, we define the IEEE 802.11b parameter value that will be used in our simulation and then we calculate the AP service rate based on the defined parameter value. The AP service rate (μ), TCP data transmission time (T TCP data ), and TCP ACK transmission time (T TCP ACK ) are as follows [6].…”

Section: Calculating Maximum Window Sizementioning

confidence: 99%

A Scheme for Enhancing TCP Fairness and Throughput in IEEE 802.11 WLANs

Lee

Lim

Seok

et al. 2007

NETWORKING 2007. Ad Hoc and Sensor Networks, Wireless Networks, Next Generation Internet

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Abstract. In this paper, we consider two fairness problems that occur in the infrastructure network (fairness between TCP uplink/downlink flows and fairness between competing TCP uplink flows). A large number of existing works have studied the TCP fairness issues and greatly solved the TCP unfairness problems. However, these solutions suffer from the drawback of TCP throughput degradation even though the TCP unfairness problem can be solved. In order to solve these problems effectively, we propose a scheme that modifies the receiver window size on the basis of maximum window size which is able to maximize link utilization. We have evaluated our scheme with ns-2 simulator and the results demonstrate that our scheme greatly improves both the TCP fairness and total throughput.

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A queueing model for HTTP traffic over IEEE 802.11 WLANs

Cited by 55 publications

References 23 publications

Throughput Analysis and Measurements in IEEE 802.11 WLANs with TCP and UDP Traffic Flows

Throughput Analysis and Measurements in IEEE 802.11 WLANs with TCP and UDP Traffic Flows

Analytical models for capacity estimation of IEEE 802.11 WLANs using DCF for internet applications

A Scheme for Enhancing TCP Fairness and Throughput in IEEE 802.11 WLANs

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