Voice transmission in an IEEE 802.11 WLAN based access network

Köpsel, Andreas; Wolisz, Adam

doi:10.1145/605992.605995

Cited by 8 publications

(6 citation statements)

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“…One such example is [3], in which physical layers supporting only 1 and 2 Mbps were considered. In [4], a wider range of data rates was considered, as well as varying channel conditions; however, in this paper, the metric of interest was mean channel access delay, rather than capacity. In [5], the capacity of an IEEE 802.11a network was evaluated, taking into account loss at the playout buffer, for a single delay constraint scenario.…”

Section: Introductionmentioning

confidence: 99%

Capacity of an IEEE 802.11b wireless LAN supporting VoIP

Hole

Tobagi

2004

2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577)

187

122

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Abstract-In this paper we evaluate the capacity of an IEEE 802.11b network carrying voice calls in a wide range of scenarios, including varying delay constraints, channel conditions and voice call quality requirements. We consider both G.711 and G.729 voice encoding schemes and a range of voice packet sizes.We first present an analytical upper bound and, using simulation, show it to be tight in scenarios where channel quality is good and delay constraints are weak or absent. We then use simulation to show that capacity is highly sensitive to the delay budget allocated to packetization and wireless network delays. We also show how channel conditions and voice quality requirements affect the capacity. Selecting the optimum amount of voice data per packet is shown to be a trade-off between throughput and delay constraints: by selecting the packet size appropriately given the delay budget and channel conditions, the capacity can be maximized.Unless a very high voice quality requirement precludes its use, G.729 is shown to allow a capacity greater than or equal to that when G.711 is used, for a given quality requirement.

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Section: Introductionmentioning

confidence: 99%

Capacity of an IEEE 802.11b wireless LAN supporting VoIP

Hole

Tobagi

2004

2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577)

187

122

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“…The former is designed for data services and the latter for real-time services like voice. Much of the previous work with respect to voice in 802.11 networks considers simulation of the PCF mode, as in [6] and [7]. However, many manufacturers are choosing not to implement the optional PCF mode, claiming that it inhibits interoperability with other access points and does not, in fact, always allocate bandwidth better than DCF [8] [9].…”

Section: Related Workmentioning

confidence: 99%

Voice performance in WLAN networks - an experimental study

Anjum¹,

Elaoud²,

Famolari³

et al.

GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489)

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-In this work, we measure Wireless Local Area Network (WLAN) voice performance and capacity. While most WLAN applications today are data centric, the growing popularity of Voice over IP (VoIP) applications and the trend towards convergence with cellular networks will catalyze increased voice traffic. Since voice applications compete not only with each other, but also with data applications for WLAN bandwidth, quantifying voice performance and capacity in the presence of simultaneous data traffic is an important issue. We offer a practical investigation of the 802.11b MAC layer's ability to support simultaneous voice and data applications. We quantify VoIP capacity for standard WLAN networks, indicative of those already in the field, as well as evaluate the practical benefits of implementing backoff control and priority queuing at the access point. Conclusions are drawn based on an extensive set of real-world measurements conducted using off-theshelf equipment in an experimental testbed. I INTRODUCTIONOnce only seen within the enterprise, Wireless Local Area Networks (WLANs) are increasingly making their way into residential, commercial, industrial and public areas. Examples of such environments are hotels, airports and coffee shops, which typically have a floating end user population. University campuses and conference settings also benefit from WLANs since they provide flexible connectivity and network access at reduced costs. While the majority of traffic in WLAN deployments is data, we expect that voice will be an increasingly important application and a significant driver for WLAN adoption and integration, particularly as voice over IP (VoIP) applications flourish. Additionally, voice will be especially important in vertical industries such as construction, healthcare, and banking, etc. Therefore it is crucial to understand voice performance in WLANs. Furthermore, since WLAN endpoints share a common transmission medium, voice applications must compete with data applications for access and bandwidth. As such, voice quality and capacity can be significantly affected by the simultaneous transmission of data traffic in these networks. So it is also critical to understand the effects of data transmissions on voice performance and capacity.We focus exclusively on IEEE 802.11b [1], the most popular and prominently deployed WLAN standard. We measure the achievable voice performance and capacity using an experimental testbed consisting of commercially available, off-the-shelf components indicative of those that have already been deployed. With such a large legacy base for 802.11b equipment, especially among residential and enterprise customers, we believe that this approach provides the most immediately relevant results.In addition to standard 802.11b, we investigate MAClayer and queuing mechanisms , which can be easily implemented and can improve voice performance. Specifically, we measure the effects of backoff control and priority queuing (BC-PQ), as provided by [2]. Using both the standard and additional...

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“…There are some works related to voice transmission in IEEE 802.11 [16] We will analyze the transmission of real-time traffic that shares resources with background traffic between a mobile ad hoc network and a fixed IP network.…”

Section: Quality Of Service Provision In Wireless Ad Hoc Networkmentioning

confidence: 99%

An Adaptive Gateway Discovery Algorithm to support QoS When Providing Internet Access to Mobile Ad Hoc Networks

Domingo

Prior²

2007

JNW

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When a node in an ad hoc network wants Internet access, it needs to obtain information about the available gateways and it should select the most appropriate of them. In this work we propose a new gateway discovery scheme suitable for real-time applications that adjusts the frequency of gateway advertisements dynamically. This adjustment is related to the percentage of real-time sources that have quality of service problems because of excessive end-to-end delays. The optimal values for the configuration parameters (time interval and threshold) of the proposed adaptive gateway discovery mechanism for the selected network conditions have been studied with the aid of simulations. The scalability of the proposed scheme with respect to mobility as well as the impact of best-effort traffic load have been analyzed. Simulation results indicate that the proposed scheme significantly improves the average end-to-end delay, jitter and packet delivery ratio of real-time flows; the routing overhead is also reduced and there is no starvation of best-effort traffic.

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Voice transmission in an IEEE 802.11 WLAN based access network

Cited by 8 publications

References 0 publications

Capacity of an IEEE 802.11b wireless LAN supporting VoIP

Capacity of an IEEE 802.11b wireless LAN supporting VoIP

Voice performance in WLAN networks - an experimental study

An Adaptive Gateway Discovery Algorithm to support QoS When Providing Internet Access to Mobile Ad Hoc Networks

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