The Experts below are selected from a list of 1341 Experts worldwide ranked by ideXlab platform
Kannan Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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vidyut exploiting power line infrastructure for enterprise wireless networks
ACM Special Interest Group on Data Communication, 2015Co-Authors: Vivek Yenamandra, Kannan SrinivasanAbstract:Global synchronization across time and frequency Domains significantly benefits wireless communications. Multi-Cell (Network) MIMO, interference alignment solutions, opportunistic routing techniques in ad-hoc networks, OFDMA etc. all necessitate synchronization in either time or frequency Domain or both. This paper presents sysname, a system that exploits the easily accessible and ubiquitous power line infrastructure to achieve synchronization in time and frequency Domains across nodes distributed beyond a Single-Collision Domain. sysname uses the power lines to transmit a reference frequency tone to which each node locks its frequency. sysname exploits the steady periodicity of delivered power signal itself to synchronize distributed nodes in time. We validate the extent of sysname's synchronization and evaluate its effectiveness. We verify sysname's suitability for wireless applications such as OFDMA and multi-cell MIMO by validating the benefits of global synchronization in an enterprise wireless network. Our experiments show a throughput gain of 8.2x over MegaMIMO, 7x over NemoX and 2.5x over OFDMA systems. Enterprise wireless networks are supported by an Ethernet backbone. Researchers have been exploring techniques over the backbone to enable and assist in improving the performance of the wireless networks. Recent work also showed the benefit of sharing information in the air between the nodes to enable higher performance of the network. Even sharing information as little as synchronization information has been demonstrated to open new avenues (such as MU-MIMO, Physical Network Coding, Opportunistic routing, etc.) for the wireless networks to enhance its performance. However, another medium shared by majority of the nodes in the enterprise network - the power line infrastructure - has been largely left untapped to assist the wireless network. While the power lines are noisy and have a frequency selective transmission characteristic, its uniqueness is that its range can extend beyond that over air while it is unburdened by switching and other responsibilities of the Ethernet backbone. This paper poses the following question: How best to exploit the opportunity presented by the power lines to further enhance enterprise wireless networks? The key contributions of this paper are the following: Identify and demonstrate the feasibility of utilizing power lines as a medium to achieve synchronization (in time and frequency Domains) between nodes in the network; Demonstrate the scalability of this technique by achieving synchronization between nodes beyond the transmission range of any of the individual nodes. The paper presents empirical results pertaining to the accuracy of synchronization and the benefit of the proposed synchronization method to existing distributed wireless techniques by virtue of extension across multiple Collision Domains.
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SIGCOMM - Vidyut: exploiting power line infrastructure for enterprise wireless networks
ACM SIGCOMM Computer Communication Review, 2015Co-Authors: Vivek Yenamandra, Kannan SrinivasanAbstract:Global synchronization across time and frequency Domains significantly benefits wireless communications. Multi-Cell (Network) MIMO, interference alignment solutions, opportunistic routing techniques in ad-hoc networks, OFDMA etc. all necessitate synchronization in either time or frequency Domain or both. This paper presents sysname, a system that exploits the easily accessible and ubiquitous power line infrastructure to achieve synchronization in time and frequency Domains across nodes distributed beyond a Single-Collision Domain. sysname uses the power lines to transmit a reference frequency tone to which each node locks its frequency. sysname exploits the steady periodicity of delivered power signal itself to synchronize distributed nodes in time. We validate the extent of sysname's synchronization and evaluate its effectiveness. We verify sysname's suitability for wireless applications such as OFDMA and multi-cell MIMO by validating the benefits of global synchronization in an enterprise wireless network. Our experiments show a throughput gain of 8.2x over MegaMIMO, 7x over NemoX and 2.5x over OFDMA systems. Enterprise wireless networks are supported by an Ethernet backbone. Researchers have been exploring techniques over the backbone to enable and assist in improving the performance of the wireless networks. Recent work also showed the benefit of sharing information in the air between the nodes to enable higher performance of the network. Even sharing information as little as synchronization information has been demonstrated to open new avenues (such as MU-MIMO, Physical Network Coding, Opportunistic routing, etc.) for the wireless networks to enhance its performance. However, another medium shared by majority of the nodes in the enterprise network - the power line infrastructure - has been largely left untapped to assist the wireless network. While the power lines are noisy and have a frequency selective transmission characteristic, its uniqueness is that its range can extend beyond that over air while it is unburdened by switching and other responsibilities of the Ethernet backbone. This paper poses the following question: How best to exploit the opportunity presented by the power lines to further enhance enterprise wireless networks? The key contributions of this paper are the following: Identify and demonstrate the feasibility of utilizing power lines as a medium to achieve synchronization (in time and frequency Domains) between nodes in the network; Demonstrate the scalability of this technique by achieving synchronization between nodes beyond the transmission range of any of the individual nodes. The paper presents empirical results pertaining to the accuracy of synchronization and the benefit of the proposed synchronization method to existing distributed wireless techniques by virtue of extension across multiple Collision Domains.
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MobiCom - BBN: throughput scaling in dense enterprise WLANs with Bind Beamforming and Nulling
Proceedings of the 20th annual international conference on Mobile computing and networking, 2014Co-Authors: Wenjie Zhou, Tarun Bansal, Prasun Sinha, Kannan SrinivasanAbstract:Today's Enterprise Wireless LANs are comprised of densely deployed access points. This paper proposes BBN, an interference nulling scheme that leverages the high density of access points to enable multiple mobile devices to transmit simultaneously to multiple access points (APs), all within a Single Collision Domain. BBN also leverages the capability of the APs to communicate with each other on the wired backbone to migrate most of the decoding complexity to the APs, while keeping the design at the mobile clients simple. Finally, we leverage the static nature of the access points to make BBN more practical in networks where the mobility of clients inhibit the use of traditional interference alignment schemes. We implement a prototype of BBN on USRP testbed showing its feasibility. The experiment results show that BBN provides a throughput gain of 1.48X over omniscient TDMA. Results from our trace-driven simulations show that BBN obtains a throughput of up to 5.6X over omniscient TDMA.
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HotMobile - RobinHood: sharing the happiness in a wireless jungle
Proceedings of the 15th Workshop on Mobile Computing Systems and Applications, 2014Co-Authors: Tarun Bansal, Wenjie Zhou, Kannan Srinivasan, Prasun SinhaAbstract:Today's Enterprise Wireless LANs are comprised of densely deployed access points. This paper proposes RobinHood, an interference nulling scheme that leverages the high density of the access points to enable multiple mobile devices to transmit simultaneously to multiple access points (APs), all within a Single Collision Domain. RobinHood also leverages the capability of the APs to communicate with each other on the wired backbone to migrate most of the complexity to the APs, while keeping the design at the mobile clients simpler. Finally, we leverage the static nature of the access points to make RobinHood more practical in networks where the mobility of clients inhibit the use of traditional interference alignment schemes. Results from our trace-driven simulations show that RobinHood obtains a throughput improvement of 6.08x and 24.2x over omniscient TDMA and IEEE 802.11, respectively.
Anthony Rowe - One of the best experts on this subject based on the ideXlab platform.
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IPSN - Demonstration abstract: how many lights do you see?
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:We demonstrate a Visual Light Communication (VLC) system that enables LED lighting luminaires to communicate with cameras on mobile devices. Each LED pulses at a frequency above the humanly perceivable flicker threshold where cameras and photodiodes can still detect changes in light intensity. Our modulation scheme supports multiple light sources in a Single Collision Domain, and works for both, line-of-sight (LOS) operation as well as from reflected surfaces like those found in architectural lighting. The spatial confinement of light makes this system ideal for use as localization landmarks. Our demonstration includes four LED ambient lights acting as location landmarks transmitting modulated data. A mobile device receiving and processing the signal displays the ID and RSSI of the closest landmark. Interacting with the system will allow users to see the practical effects of multiple-access, frequency of operation, distance from the lights, camera parameters and camera motion.
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IPSN - Visual light landmarks for mobile devices
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobile devices. In this paper, we present a communication scheme that enables interior ambient LED lighting systems to send data to mobile devices using either cameras or light sensors. By exploiting rolling shutter camera sensors that are common on tablets, laptops and smartphones, it is possible to detect high-frequency changes in light intensity reflected off of surfaces and in direct line-of-sight of the camera. We present a demodulation approach that allows smartphones to accurately detect frequencies as high as 8kHz with 0.2kHz channel separation. In order to avoid humanly perceivable flicker in the lighting, our system operates at frequencies above 2kHz and compensates for the non-ideal frequency response of standard LED drivers by adjusting the light's duty-cycle. By modulating the PWM signal commonly used to drive LED lighting systems, we are able to encode data that can be used as localization landmarks. We show through experiments how a binary frequency shift keying modulation scheme can be used to transmit data at 1.25 bytes per second (fast enough to send an ID code) from up to 29 unique light sources simultaneously in a Single Collision Domain. We also show how tags can demodulate the same signals using a light sensor instead of a camera for low-power applications.
Niranjini Rajagopal - One of the best experts on this subject based on the ideXlab platform.
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Visual Light Landmarks for Mobile Devices
2018Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony G. RoweAbstract:The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobiledevices. In this paper, we present a communication scheme that enables interior ambient LED lightingsystems to send data to mobile devices using either cameras or light sensors. By exploiting rolling shutter camera sensors that are common on tablets, laptops and smartphones, it is possible to detect high-frequency changes in light intensity reflected off of surfaces and in direct line-of-sight of the camera. We present a demodulation approach that allows smartphones to accurately detect frequencies as high as 8kHz with 0.2kHz channel separation. In order to avoid humanly perceivable flicker in the lighting, our system operates at frequencies above 2kHz and compensates for the non-ideal frequency response of standard LED drivers by adjusting the light's duty-cycle. By modulating the PWM signal commonly used to drive LED lighting systems, we are able to encode data that can be used as localization landmarks. We show through experiments how a binary frequency shift keying modulation scheme can be used to transmit data at 1.25 bytes per second (fast enough to send an ID code) from up to 29 unique light sources simultaneously in a Single Collision Domain. We also show how tags can demodulate the same signals using a light sensor instead of a camera for low-power applications.
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IPSN - Demonstration abstract: how many lights do you see?
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:We demonstrate a Visual Light Communication (VLC) system that enables LED lighting luminaires to communicate with cameras on mobile devices. Each LED pulses at a frequency above the humanly perceivable flicker threshold where cameras and photodiodes can still detect changes in light intensity. Our modulation scheme supports multiple light sources in a Single Collision Domain, and works for both, line-of-sight (LOS) operation as well as from reflected surfaces like those found in architectural lighting. The spatial confinement of light makes this system ideal for use as localization landmarks. Our demonstration includes four LED ambient lights acting as location landmarks transmitting modulated data. A mobile device receiving and processing the signal displays the ID and RSSI of the closest landmark. Interacting with the system will allow users to see the practical effects of multiple-access, frequency of operation, distance from the lights, camera parameters and camera motion.
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IPSN - Visual light landmarks for mobile devices
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobile devices. In this paper, we present a communication scheme that enables interior ambient LED lighting systems to send data to mobile devices using either cameras or light sensors. By exploiting rolling shutter camera sensors that are common on tablets, laptops and smartphones, it is possible to detect high-frequency changes in light intensity reflected off of surfaces and in direct line-of-sight of the camera. We present a demodulation approach that allows smartphones to accurately detect frequencies as high as 8kHz with 0.2kHz channel separation. In order to avoid humanly perceivable flicker in the lighting, our system operates at frequencies above 2kHz and compensates for the non-ideal frequency response of standard LED drivers by adjusting the light's duty-cycle. By modulating the PWM signal commonly used to drive LED lighting systems, we are able to encode data that can be used as localization landmarks. We show through experiments how a binary frequency shift keying modulation scheme can be used to transmit data at 1.25 bytes per second (fast enough to send an ID code) from up to 29 unique light sources simultaneously in a Single Collision Domain. We also show how tags can demodulate the same signals using a light sensor instead of a camera for low-power applications.
Paolo Santi - One of the best experts on this subject based on the ideXlab platform.
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Maximizing throughput in MIMO networks with variable rate streams
2010 European Wireless Conference (EW), 2010Co-Authors: Ramya Srinivasan, Douglas M Blough, Luis Miguel Cortes-pena, Paolo SantiAbstract:The problem that we consider is that of maximizing throughput in a MIMO network while accounting for variable rate streams on MIMO links. The stream rates on a link depend on the channel conditions of the link, and the manner in which the diversity-multiplexing tradeoff is handled. In this work, we use the dependence of stream rates on the channel to develop methods of link selection and stream allocation that approximately maximize the aggregate throughput. Maximizing throughput is closely tied to the problem of allocating streams based on the stream rates of the selected links. Doing this optimally is very complex even for networks with 10 or fewer links. We develop a stream allocation heuristic that approximately maximizes the throughput over a given set of links. Simulation results for Single Collision Domain networks show that our stream allocation heuristic is within 7% of optimal in networks with up to 10 links (in a typical case where the maximum concurrency allowed is 15 links). The algorithm also cuts the difference between heuristic and optimal results in half, compared to a simple greedy algorithm. Our research has also identified the feasibility checking problem for general MIMO networks as being a computationally hard problem. However, we also identify several practical special cases, e.g. when interference suppression is done only at the receiver side, for which feasibility checking remains a polynomial-time operation.
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optimal one shot stream scheduling for mimo links in a Single Collision Domain
Sensor Mesh and Ad Hoc Communications and Networks, 2009Co-Authors: Ramya Srinivasan, Douglas M Blough, Paolo SantiAbstract:This paper considers the problem of scheduling the maximum number of streams in a Single time slot under the MIMO degrees of freedom (DOF) model, when all links are in a Single Collision Domain. In the DOF model, nodes can use degrees of freedom provided by their antenna arrays to multiplex multiple streams on a Single link and/or cancel interference between concurrently transmitting links. Given a set of links with data to transmit that are free of primary interference, we provide optimal constructions for both the case where only spatial reuse (from interference cancellation) is allowed and the case where both spatial reuse and spatial multiplexing can be done simultaneously. Our analysis allows deriving clean throughput performance trends when the number of available DOFs is arbitrarily increased. These trends show that combining spatial multiplexing with spatial reuse can arbitrarily increase throughput compared to spatial reuse only, and that close to two-fold throughput increases can be achieved compared to spatial multiplexing only. Finally, we show how the approach can be extended to deal with primary interference and optimally solve the one-shot stream scheduling problem for an arbitrary set of MIMO links in a Single Collision Domain.
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SECON - Optimal One-Shot Stream Scheduling for MIMO Links in a Single Collision Domain
2009 6th Annual IEEE Communications Society Conference on Sensor Mesh and Ad Hoc Communications and Networks, 2009Co-Authors: Ramya Srinivasan, Douglas M Blough, Paolo SantiAbstract:This paper considers the problem of scheduling the maximum number of streams in a Single time slot under the MIMO degrees of freedom (DOF) model, when all links are in a Single Collision Domain. In the DOF model, nodes can use degrees of freedom provided by their antenna arrays to multiplex multiple streams on a Single link and/or cancel interference between concurrently transmitting links. Given a set of links with data to transmit that are free of primary interference, we provide optimal constructions for both the case where only spatial reuse (from interference cancellation) is allowed and the case where both spatial reuse and spatial multiplexing can be done simultaneously. Our analysis allows deriving clean throughput performance trends when the number of available DOFs is arbitrarily increased. These trends show that combining spatial multiplexing with spatial reuse can arbitrarily increase throughput compared to spatial reuse only, and that close to two-fold throughput increases can be achieved compared to spatial multiplexing only. Finally, we show how the approach can be extended to deal with primary interference and optimally solve the one-shot stream scheduling problem for an arbitrary set of MIMO links in a Single Collision Domain.
Patrick Lazik - One of the best experts on this subject based on the ideXlab platform.
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Visual Light Landmarks for Mobile Devices
2018Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony G. RoweAbstract:The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobiledevices. In this paper, we present a communication scheme that enables interior ambient LED lightingsystems to send data to mobile devices using either cameras or light sensors. By exploiting rolling shutter camera sensors that are common on tablets, laptops and smartphones, it is possible to detect high-frequency changes in light intensity reflected off of surfaces and in direct line-of-sight of the camera. We present a demodulation approach that allows smartphones to accurately detect frequencies as high as 8kHz with 0.2kHz channel separation. In order to avoid humanly perceivable flicker in the lighting, our system operates at frequencies above 2kHz and compensates for the non-ideal frequency response of standard LED drivers by adjusting the light's duty-cycle. By modulating the PWM signal commonly used to drive LED lighting systems, we are able to encode data that can be used as localization landmarks. We show through experiments how a binary frequency shift keying modulation scheme can be used to transmit data at 1.25 bytes per second (fast enough to send an ID code) from up to 29 unique light sources simultaneously in a Single Collision Domain. We also show how tags can demodulate the same signals using a light sensor instead of a camera for low-power applications.
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IPSN - Demonstration abstract: how many lights do you see?
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:We demonstrate a Visual Light Communication (VLC) system that enables LED lighting luminaires to communicate with cameras on mobile devices. Each LED pulses at a frequency above the humanly perceivable flicker threshold where cameras and photodiodes can still detect changes in light intensity. Our modulation scheme supports multiple light sources in a Single Collision Domain, and works for both, line-of-sight (LOS) operation as well as from reflected surfaces like those found in architectural lighting. The spatial confinement of light makes this system ideal for use as localization landmarks. Our demonstration includes four LED ambient lights acting as location landmarks transmitting modulated data. A mobile device receiving and processing the signal displays the ID and RSSI of the closest landmark. Interacting with the system will allow users to see the practical effects of multiple-access, frequency of operation, distance from the lights, camera parameters and camera motion.
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IPSN - Visual light landmarks for mobile devices
IPSN-14 Proceedings of the 13th International Symposium on Information Processing in Sensor Networks, 2014Co-Authors: Niranjini Rajagopal, Patrick Lazik, Anthony RoweAbstract:The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobile devices. In this paper, we present a communication scheme that enables interior ambient LED lighting systems to send data to mobile devices using either cameras or light sensors. By exploiting rolling shutter camera sensors that are common on tablets, laptops and smartphones, it is possible to detect high-frequency changes in light intensity reflected off of surfaces and in direct line-of-sight of the camera. We present a demodulation approach that allows smartphones to accurately detect frequencies as high as 8kHz with 0.2kHz channel separation. In order to avoid humanly perceivable flicker in the lighting, our system operates at frequencies above 2kHz and compensates for the non-ideal frequency response of standard LED drivers by adjusting the light's duty-cycle. By modulating the PWM signal commonly used to drive LED lighting systems, we are able to encode data that can be used as localization landmarks. We show through experiments how a binary frequency shift keying modulation scheme can be used to transmit data at 1.25 bytes per second (fast enough to send an ID code) from up to 29 unique light sources simultaneously in a Single Collision Domain. We also show how tags can demodulate the same signals using a light sensor instead of a camera for low-power applications.