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16
R2D2: Regulating Beam Shape and Rate as Directionality meets Diversity
, 2009
"... We design, implement, and evaluate a vehicular communication system that improves uplink connectivity through multi-lobe beam pattern switching on a smart antenna. Directionality and base station-diversity are two well-known, independently developed mechanisms for improving the uplink connectivity o ..."
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Cited by 13 (3 self)
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We design, implement, and evaluate a vehicular communication system that improves uplink connectivity through multi-lobe beam pattern switching on a smart antenna. Directionality and base station-diversity are two well-known, independently developed mechanisms for improving the uplink connectivity of mobile clients. In this paper, we highlight that a system combining both mechanisms can achieve significant improvement in performance with multi-lobe beams that strike a tradeoff between directionality and diversity. This is in contrast to the mere steering of narrow beams used in conventional smart antenna systems. For tractability at vehicular speeds, our R2D2 system searches through a limited set of beam patterns with different numbers of lobes, and includes a two-stage algorithm that uses both runtime adaptation and cached candidate patterns. We design and evaluate several variants of run-time adaptation that tune the number and angle of lobes in the beam, and the bit rate. The design of these algorithms is guided by both analysis and real-world measurements with a smart antenna system mounted on a vehicle. These measurements with our prototype implementation show that R2D2 can achieve an uplink throughput increase of up to 154 % over pure beamsteering and 45 % over pure basestation diversity.
Inter-vehicular communication systems, protocols and middleware
- IEEE International Conference on Networking, Architecture, and Storage
, 2010
"... Abstract—Inter-vehicular communication is an important research area that is rapidly growing due to considerable advances in mobile and wireless communication technologies, as well as the growth of microprocessing capabilities inside today’s cars, and other moving vehicles. A good amount of research ..."
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Abstract—Inter-vehicular communication is an important research area that is rapidly growing due to considerable advances in mobile and wireless communication technologies, as well as the growth of microprocessing capabilities inside today’s cars, and other moving vehicles. A good amount of research has been done to exploit the different services that can be provided to enhance the safety and comfort of the driver. Additional functions provide the car electronics and the passengers with access to the Internet and other core network resources. This paper provides a survey of the latest advances in the area of inter-vehicular communication (IVC) including vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) functions and services. In addition, the paper presents the most important projects and protocols that are involved in IVC systems as well as the different issues and challenges that exist at each layer of the networking model.
Experimental Characterization of Sectorized Antennas in Dense 802.11 Wireless Mesh Networks
"... Sectorized antennas can increase wireless network capacity through greater spatial reuse. Despite their increasing popularity, their real-world performance characteristics in dense wireless mesh networks are not well understood. This paper conducts a systematic experimental study on a mesh network t ..."
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Sectorized antennas can increase wireless network capacity through greater spatial reuse. Despite their increasing popularity, their real-world performance characteristics in dense wireless mesh networks are not well understood. This paper conducts a systematic experimental study on a mesh network testbed using commodity 802.11 hardware and multisector antennas. Our study results in the following main observations. (i) Sector selection should be based on explicit measurement in all sectors, though the measurement overhead can be significantly reduced by exploiting spatio-temporal characteristics of the best sector. (ii) Multi-sector activation typically reduces the signal strength of a link compared to single sector activations due to antenna design constraints. (iii) Spatial reuse is constrained by characteristics of antenna radiation pattern in different sectors (iv) Physical layer capture reduces the effect of directional hidden terminal problem. Finally, we discuss the implications of these observations on the design of practical directional MAC and topology control protocols.
Coding-Based System Primitives for Airborne Cloud Computing
, 2011
"... The recent proliferation of sensors in inhospitable environments such as disaster or battle zones has not been matched by in situ data processing capabilities due to a lack of computing infrastructure in the field. We envision a solution based on small, low-altitude unmanned aerial vehicles (UAVs) t ..."
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The recent proliferation of sensors in inhospitable environments such as disaster or battle zones has not been matched by in situ data processing capabilities due to a lack of computing infrastructure in the field. We envision a solution based on small, low-altitude unmanned aerial vehicles (UAVs) that can deploy elastically-scalable computing infrastructure anywhere, at any time. This airborne compute cloud— essentially, micro-data centers hosted on UAVs—would communicate with terrestrial assets over a bandwidth-constrained wireless network with variable, unpredictable link qualities. Achieving high performance over this ground-to-air mobile radio channel thus requires making full and efficient use of every single transmission opportunity. To this end, this dissertation presents two system primitives that improve throughput and reduce network overhead by using recent distributed coding methods to exploit natural properties of the airborne environment (i.e., antenna beam diversity and anomaly sparsity).
BeamSwitch: System Solution for Energy-Efficient Directional Communication on Mobile Devices
"... Abstract: Directional communication has the potential to improve the energy efficiency of wireless communication without sacrificing its quality. We present a system solution, BeamSwitch, for directional communication on mobile devices. BeamSwitch employs a special multi-antenna system that consists ..."
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Abstract: Directional communication has the potential to improve the energy efficiency of wireless communication without sacrificing its quality. We present a system solution, BeamSwitch, for directional communication on mobile devices. BeamSwitch employs a special multi-antenna system that consists of multiple identical directional antennas 1, or beams, a single regular omni-directional antenna, and a single RF chain. It uses one of the directional beams for transmitting data frames and receiving their acknowledgements and the regular antenna for all other transceiving. BeamSwitch tracks the signal strength of incoming frames and selects the right beam for data transmission. We report an extensive evaluation of BeamSwitch including both measurements with a prototype with three beams and Qualnet-based simulation. Our evaluation shows that BeamSwitch with three 6 dBi directional antennas can improve the energy efficiency of a commercial 802.11 network interface card (NIC) by up to 20 % and simultaneously provide better or close communication quality. BeamSwitch achieves this under diverse radio propagation environments and extreme mobility (up to 360 ° per second direction change). 1.
A Trust-based Message Evaluation and Propagation Framework in Vehicular Ad-Hoc Networks
"... I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii In this paper, we propose a trust-based message propag ..."
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I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii In this paper, we propose a trust-based message propagation and evaluation frame-work to support the effective evaluation of information sent by peers and the immediate control of false information in a VANET. More specifically, our trust-based message prop-agation collects peers trust opinions about a message sent by a peer (message sender) during the propagation of the message. We improve on an existing cluster-based data routing mechanism by employing a secure and efficient identity-based aggregation scheme for the aggregation and propagation of the senders message and the trust opinions. These trust opinions weighted by the trustworthiness of the peers modeled using a combination of role-based and experience-based trust metrics are used by cluster leaders to compute a ma jority opinion about the senders message, in order to proactively detect false informa-
On the performance of STDMA Link Scheduling and Switched Beamforming Antennas in Wireless Mesh Networks
, 2009
"... Wireless Mesh Networks (WMNs) aim to revolutionize Internet connectivity due to its high throughput, cost-effectiveness and ease deployment by providing last mile connectivity and/or backhaul support to different cellular networks. In order not to jeopardize their successful deployment, several key ..."
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Wireless Mesh Networks (WMNs) aim to revolutionize Internet connectivity due to its high throughput, cost-effectiveness and ease deployment by providing last mile connectivity and/or backhaul support to different cellular networks. In order not to jeopardize their successful deployment, several key issues must be investigated and overcome to fully realize its potential. For WMNs that utilize Spatial Reuse TDMA as the medium access control, link scheduling still requires further enhancements. The first main contribution of this thesis is a fast randomized parallel link swap based packing (RSP) algorithm for timeslot allocation in a spatial time division mul-tiple access (STDMA) wireless mesh network. The proposed randomized algorithm extends several greedy scheduling algorithms that utilize the physical interference model by applying a local search that leads to a substantial improvement in the spatial timeslot reuse. Numerical simulations reveal that compared to previously scheduling schemes the proposed randomized algorithm can achieve a performance gain of up to 11%. A significant benefit of the proposed scheme is that the com-
R2D2: Regulating Beam Shape and Rate as
, 2016
"... All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
AdaptiveAntennaAdjustmentfor3D UrbanWirelessMeshNetworks
"... Abstract—We design and evaluate a new type of wireless mesh nodes called Dyntenna nodes that are equipped with steerable omnidirectionalantenna.Designedfor3D wirelessmeshnetworks, these nodes adaptively adjust the antenna orientation to increase throughput by improving the Received Signal Strength I ..."
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Abstract—We design and evaluate a new type of wireless mesh nodes called Dyntenna nodes that are equipped with steerable omnidirectionalantenna.Designedfor3D wirelessmeshnetworks, these nodes adaptively adjust the antenna orientation to increase throughput by improving the Received Signal Strength Indicator (RSSI) reading between nodes. We demonstrate the importance of being able to programmatically orient the antenna, by presenting the measurement results from our 3D urban mesh testbed. We propose a simple antenna adjustment algorithm that can improve the throughput for 26 % of one-hop paths and 35 % of multi-hop paths by a median value of 31 % and 46%, respectively. Our algorithm converges quickly and typically probes less than 10% of all possible antenna orientations on average. I.
An Overview of Inter-Vehicular Communication Systems, Protocols and Middleware
"... Abstract — Inter-vehicular communication is an important research area that is rapidly growing due to considerable advances in mobile and wireless communication technologies, as well as the growth of microprocessing capabilities inside today’s cars, and other moving vehicles. A good amount of resear ..."
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Abstract — Inter-vehicular communication is an important research area that is rapidly growing due to considerable advances in mobile and wireless communication technologies, as well as the growth of microprocessing capabilities inside today’s cars, and other moving vehicles. A good amount of research has been done to exploit the different services that can be provided to enhance the safety and comfort of the driver. Additional functions provide the car electronics and the passengers with access to the Internet and other core network resources. This paper provides a survey of the latest advances in the area of inter-vehicular communication (IVC) including vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) functions and services. In addition, the paper presents the most important projects and protocols that are involved in IVC systems as well as the different issues and challenges that exist at each layer of the networking model.
