Martin Kappes

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— In this paper, we study the inherent limitations of the 802.11 (a/b) distributed coordination function (DCF) in supporting VoIP calls over a wireless LAN. Specifically, we evaluate the upper bound on the number of simultaneous VoIP calls that can be placed in a single cell of an 802.11(a/b) network. Making one additional VoIP call in that cell would(More)
—In this paper, we present experimental studies on the throughput of IEEE 802.11b wireless networks for UDP and VoIP traffic. Our experiments show that the maximum data throughput of a single station sending out UDP traffic is 6.1 Mbps. The maximum number of VoIP calls in a single cell of an IEEE 802.11b network is six if the ITU G711a-Law codec is used(More)
— In this paper, we propose a metric for measuring the utilization of an IEEE 802.11b wireless network and outline how this metric can be accurately estimated using data that is readily available in most Access Points. We furthermore describe how this metric can be used to perform admission control for VoIP traffic and describe experiences with a prototype(More)
Over the last 30 years or so many results have appeared on the descriptional complexity of machines with limited resources. Since these results have appeared in a variety of different contexts, our goal here is to provide a survey of these results. Particular emphasis is put on limiting resources (e.g., nondeterminism, ambiguity, lookahead, etc.) for(More)
— Current " best practice " recommendations for enterprise wireless deployments suggest the use of VPNs from a wireless client for both authentication and privacy. In this paper, we demonstrate a security issue with such deployments, which we refer to as the hidden wireless router vulnerability. This vulnerability is inherent in the VPN-based wireless LAN(More)
In this paper, we present experimental studies on the use of MAC multicast in IEEE 802.11b wireless networks. Our experiments show that the maximal throughput achievable in such networks is 1.76 Mbps for an 802.11 Data Rate of 2 Mbps. We study the behavior of VoIP traffic over MAC multicast in such networks in multi-hop scenarios with and without hidden(More)