M. A. Visser and M. E. Zarki, Voice and data transmission over an  Home/Search   Document Not in Database   Summary   Related Articles   Check

....such as low medium utilization, risk of collisions and problem of providing differentiation between different types of traffic. There is a mode of operation in IEEE 802.11 that can be used to provide service differentiation, but it has been shown to perform poorly and give poor link utilization [15], so several new service differentiation schemes have been proposed. We study and evaluate four schemes for providing Quality of Service (QoS) over IEEE 802.11 wireless LANs: the PCF mode of the IEEE 802.11 standard [8] Distributed Fair Scheduling [14] Blackburst [12] and Enhanced DCF [2] ....

M.A. Visser and M. El Zarki, Voice and data transmission over an 802.11 wireless network, in: Proceedings of PIMRC'95, Toronto, Canada (1995.

....more than best effort service for the mobile hosts. To support real time services, the standard provides a polling based media access in the point coordination function (PCF) mode. However, PCF is not supported by most wireless vendors and has been shown to perform poorly in the presence of DCF [29]. As a result, the 802.11 Working Group is considering proposals for introducing QoS enhancements into the standard. One of these proposals calls for the use of per flow resource based admission control combined with prioritized data transmission for real time traffic [3] However, this scheme ....

M. A. Visser and M. E. Zarki. Voice and Data Transmission over an 802.11 Wireless Network. In Proc. PIMRC'95, pages 648--652, September 1995.

....method for the transmission of voice and data is attractive. In this paper we investigate the suitability of IEEE 802.11 for the parallel usage for voice and data in an IEEE 802.11 WLAN using DCF and PCF mode of operation. Previous research has postulated a high overhead in PCF mode of operation [2, 3, 4, 5], so providing real time support is still an open issue in wireless LANs. Several approaches currently compete for providing QoS enhancements in IEEE 802.11 : 1. Quality of Service might be achieved by using a distributed or centralized coordination scheme. In [6] a QoS enhanced signaling scheme ....

....their conversation; this e ect is known as Talkspurt. This behavior is independent from the codec used and is modeled by a two State Markov chain. The resulting packet train has exponentially distributed on and o periods with mean values talk = 1:35 ms and silence = 1:15 ms according to [2]. During TALK periods an audio ow is represented as an isochronous source with xed interarrival times that are determined by the audio codec. According to the employed audio codec the amount of data for conveying speech data and the interarrival times vary as shown in table 1. 3.1.0.2 Audio QoS ....

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M.Visser and M.ElZarki, \Voice and data transmission over an 802.11 wireless network," in Proceedings of IEEE Personal., Indoor & Mobile Radio Conf. (PIMRC)

....differentiation and consequently avoids starvation of low priority traffic. 1. Introduction The IEEE 802.11 standard [5] for WLANs is the most widely used WLAN standard today. It has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly [7]. We study and evaluate four schemes for providing QoS over IEEE 802.11 wireless LANs; the PCF mode of the IEEE 802.11 standard [5] Distributed Fair Scheduling [6] Blackburst [4] and Enhanced DCF [1] This paper is a continuation of previous work where some initial comparisons between QoS ....

M. A. Visser and M. El Zarki. Voice and data transmission over an 802.11 wireless network. In Proceedings of PIMRC'95, Toronto, Canada, pages 648--652, September 1995.

....low bandwidth in these networks, the introduction of Quality of Service is indispensable. The IEEE 802.11 standard [6] for WLANs is the most widely used WLAN standard today. It contains a mode for service differentiation, but that has been shown to perform badly and give poor link utilization [8]. We study and evaluate four schemes for providing QoS over IEEE 802.11 wireless LANs, the PCF mode of the IEEE 802.11 standard [6] Distributed Fair Scheduling [7] Blackburst [4] and a scheme proposed by Deng et al. 1] 1.1 IEEE 802.11 IEEE 802.11 has two different access methods, the ....

M. A. Visser and M. El Zarki. Voice and data transmission over an 802.11 wireless network. In Proceedings of PIMRC'95, Toronto, Canada, pages 648--652, September 1995. 3 ON-OFF sources with ON and OFF periods from a Pareto distribution

....we have chosen the most basic form of communication, voice. A twoState Markov model is used to simulate PCM style 64 kbps audio sources with talkspurts. The resulting packet train has exponentially distributed on and o periods with mean values talk = 1:35 ms and silence = 1:15 ms according to [5]. An audio ow represents an isochronous source with xed interarrival times of 20 ms emitting speech samples containing a payload of 160 bytes. During state Talk, packets are generated with a frequency of 50 Hz and are stored in a non blocking transmission queue. A deadline and a maximum lifetime ....

....protocol overhead, but the coordinated medium access in PCF mode outperforms the DCF medium access at a certain load level. 5 Capacity of PCF for audio ows IEEE 802.11 supports time bounded services by introducing a contention free polling based medium access scheme. Earlier papers (see [1, 5]) have shown a high overhead and low absolute number of conveyable audio streams in PCF mode. With the increasing WLAN bandwidth up to 54Mbps in the near future the use of the DCF for real time communication will become attractive. Therefore, we have compared the overall WLAN performance ....

M. Visser and M. ElZarki. Voice and data transmission over an 802.11 wireless network. In Proceedings of IEEE Personal., Indoor & Mobile Radio Conf. (PIMRC) 1995, Toronto, Canada, pages 648-652, Sept. 1995.

.... difficult (but somewhat tedious) to take noise into consideration; also, hidden terminals require a separate model and, in any case, should be analyzed together with RTS CTS because the two are closely related [BFO, CG, HC] In contrast to previous simulation studies of the 802.11 MAC protocols [BFO, NI, VE], the performance analysis we present here is based on a mathematical model. This model not only differs from previous analytic models of the 802.11 protocols [CG, HC] it is also different from the other techniques in the CSMA literature [AS, HLR, KT, PSP, S, TT, TK] Our technique is simple, yet ....

M. Visser and M. El Zarki, Voice and data transmission over an 802.11 wireless network, Proc. PIMRC, Toronto, Canada (Sept. 1995), 648--652. 22

....5. Related Work The IEEE 802.11 standard [1] is an emerging MAC standard that aims to provide real time network access by switching channel access modes for CSMA CA LANs. 802.11 switches to a polled mode of operation to support performance guarantees, which is reported not to perform very well [4] [8] An additional constraint is that neighboring cells can not be in the polling mode simultaneously. A related work at Bell Labs [8] aims at providing real time guarantees on a wireless network by equipping individual stations with the ability to jam the channel with pulses of energy of ....

M.A.Visser and M. Zarki. Voice and data transmission over an 802.11 wireless network. PIMRC, pages 648--652, September 1995.

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M. A. Visser and M. E. Zarki, Voice and data transmission over an

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M. A. Visser and M. E. Zarki, Voice and data transmission over an

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M. Visser, M. Zarki, Voice and data transmission over an 802.11 wireless network, Proceedings of IEEE PIMRC (1995) 648 -- 652.

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M. A. Visser and M. El Zarki. Voice and data transmission over an 802.11 wireless network. In 6th IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications, volume 2, pages 648--652. Institute of Electrical and Electronics Engineers, 1995.

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Matthijs A. Visser and Magda El Zarki. Voice and Data transmission over an 802.11 Wireless network. Proc. of IEEE PIMRC `95.

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Visser MA and Zarki ME. Voice and data transmission over an 802.11 wireless network, in Proceedings of PIMRC, Toronto, Canada, Sept. 1995

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Matthijs A. Visser and Magda El Zarki. Voice and data transmission over an 802.11 wireless network. In Proceedings of PIMRC'95, Toronto, Canada, pages 648--652, September 1995.

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