32 research outputs found
Cross-layer Design for Interference Mitigation and Mobility Support in Wireless Access Networks
No full textStony Brook University Libraries.
SBU Graduate School in Computer Science.
Lawrence Martin (Dean of Graduate School), Dr. Samir R. Das
Advisor
Associate Professor of Computer Science, Dr. Tzi-cker Chiueh
Professor of Computer Science, Dr. Himanshu Gupta
Assistant Professor of Computer Science, Dr. Samrat Ganguly
Research Staff Member
NEC Labs America at Princeton
Cross-layer Design for Interference Mitigation and Mobility Support in Wireless Access Networks
No full text[to be added
Design and evaluation of iMesh: An infrastructure-mode wireless mesh network
No full textWe design and evaluate iMesh, an infrastructure-mode 802.11-based mesh network. Here, 802.11 access points double as routers making the network architecture completely transparent to mobile clients, who view the network as a conventional wireless LAN. Layer-2 handoffs between access points trigger routing activities inside the network, which can be thought of as layer-3 handoffs. We describe the design rationale, and a testbed implementation of iMesh. We present results related to the handoff performance. The results demonstrate excellent handoff performance, the overall latency varying between 50-100ms depending on different layer-2 techniques, even when a fivehop long route update is needed. Various performance measurements also demonstrate the clear superiority of a flat routing scheme relative to a more traditional, mobile IPlike scheme to handle layer-3 handoff.
Using channel hopping to increase 802.11 resilience to jamming attacks
No full textAbstract—802.11a, b, and g standards were designed for deployment in cooperative environments, and hence do not include mechanisms to protect from jamming attacks. In this paper, we explore how to protect 802.11 networks from jamming attacks by having the legitimate transmission hop among channels to hide the transmission from the jammer. Using a combination of mathematical analysis and prototype experimentation in an 802.11a environment, we explore how much throughput can be maintained in comparison to the maintainable throughput in a cooperative, jam-free environment. Our experimental and analytical results show that in today’s conventional 802.11a networks, we can achieve up to 60 % of the original throughput. Our mathematical analysis allows us to extrapolate the throughput that can be maintained when the constraint on the number of orthogonal channels used for both legitimate communication and for jamming is relaxed. I
A measurement study of inter-vehicular communication using steerable beam directional antenna
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DiversiFi: Robust Multi-Link Interactive Streaming
No full textABSTRACT Real-time, interactive streaming for applications such as audio-video conferencing (e.g., Skype) and cloud-based gaming depends critically on the network providing low latency, jitter, and packet loss, much more so than on-demand streaming (e.g., YouTube) does. However, WiFi networks pose a challenge; our analysis of data from a large VoIP provider and from our own measurements shows that the WiFi access link is a significant cause of poor streaming experience. To improve streaming quality over WiFi, we present DiversiFi, which takes advantage of the diversity of WiFi links available in the vicinity, even when the individual links are poor. Leveraging such cross-link spatial and channel diversity outperforms both traditional link selection and the temporal diversity arising from retransmissions on the same link. It also provides significant gains over and above the PHY-layer spatial diversity provided by MIMO. Our experimental evaluation shows that, for a client with two NICs, enabling replication across two WiFi links helps cut down the poor call rate (PCR) for VoIP by 2.24x. Finally, we present the design and implementation of DiversiFi, which enables it to operate with single-NIC clients, and with either minimally modified APs or unmodified APs augmented with a middlebox. Over 61 runs, where the baseline average PCR is 4.9%, DiversiFi running with a single NIC, switching between two links, helps cut the PCR down to 0%, while duplicating wastefully only 0.62% of the packets and impacting competing TCP throughput by only 2.5%. Thus, DiversiFi provides the benefit of multi-link diversity for real-time interactive streaming in a manner that is deployable and imposes little overhead, thereby ensuring coexistence with other applications
