The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

H.v. Poor - One of the best experts on this subject based on the ideXlab platform.

  • A Cross-Layer Approach to Collaborative Beamforming for Wireless Ad Hoc Networks
    IEEE Transactions on Signal Processing, 2008
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a medium access control-physical (MAC-PHY) cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each collaborating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. Analyses of the average beampattern, networking performance, and symbol error probability corresponding to the proposed scheme are provided.

  • PIMRC - Energy efficient communication using cooperative beamforming: A game theoretic analysis
    2008 IEEE 19th International Symposium on Personal Indoor and Mobile Radio Communications, 2008
    Co-Authors: S.m. Betz, H.v. Poor
    Abstract:

    In this paper, a game-theoretic model for studying power control in large data networks using cooperative beamforming is analyzed. Cooperating nodes form clusters to retransmit local signals to faraway destinations. Within each cluster, nodes multiply the received Analog Waveform by a complex weight chosen in a distributed fashion to maximize the received SNR. This work analyzes the scenario in which multiple such clusters are transmitting at the same frequency at the same time. A game where each cluster chooses its average transmit power to optimize the total number of bits it transmits per unit of transmit energy is proposed and the resulting unique Nash equilibrium is described.

  • Cooperative Beamforming and Power Control
    2007 Conference Record of the Forty-First Asilomar Conference on Signals Systems and Computers, 2007
    Co-Authors: S.m. Betz, H.v. Poor, Athina P. Petropulu
    Abstract:

    This work presents an energy efficient, low-overhead scheme for cooperative beamforming in ad hoc networks. Collaborating nodes retransmit local signals to faraway destinations, multiplying the received Analog Waveform by a complex weight chosen (in a distributed fashion) to maximize the received SNR. The improvement in SNR is explicitly derived for a large number of cooperating nodes.

  • CISS - A High-Throughput Cross-Layer Scheme for Distributed Wireless Ad Hoc Networks
    2007 41st Annual Conference on Information Sciences and Systems, 2007
    Co-Authors: Athina P. Petropulu, Lun Dong, H.v. Poor
    Abstract:

    In wireless ad hoc networks, distributed nodes can collaboratively form an antenna array for long-distance communications to achieve high energy efficiency. In recent work, Ochiai, et al., have shown that such collaborative beamforming can achieve a statistically nice beampattern with a narrow main lobe and low side lobes. However, the process of collaboration introduces significant delay, since all collaborating nodes need access to the same information. In this paper, a technique that significantly reduces the collaboration overhead is proposed. It consists of two phases. In the first phase, nodes transmit locally in a random access fashion. Collisions, when they occur, are viewed as linear mixtures of the collided packets. In the second phase, a set of cooperating nodes acts as a distributed antenna system and beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex number, which is independently computed by each cooperating node, and which enables separation of the collided packets based on their final destination. The scheme requires that each node has global knowledge of the network coordinates. The proposed scheme can achieve high throughput, which in certain cases exceeds one.

  • GLOBECOM - Cooperative Beamforming for Wireless Ad Hoc Networks
    IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a MAC-PHY cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each cooperating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. An analysis of the symbol error probability corresponding to the proposed scheme is provided.

Wooley - One of the best experts on this subject based on the ideXlab platform.

  • A 700-MHz switched capacitor Analog Waveform sampling circuit
    Symposium on VLSI Circuits, 1993
    Co-Authors: Haller, Wooley
    Abstract:

    Analog switched capacitor memory devices are suitable for use in a wide range of applications where Analog Waveforms and signals must be captured or delayed. A switched-capacitor Analog memory circuit intended for use in high-speed, low-power data acquisition systems operating at frequencies up to 700 MHz is described. A two-channel version of the circuit with 32 memory cells for each channel has been integrated in a 2 /spl mu/m CMOS technology with poly-poly capacitors. One memory channel dissipates 0.9 mW while operating from a single +5 V supply.

Athina P. Petropulu - One of the best experts on this subject based on the ideXlab platform.

  • A Cross-Layer Approach to Collaborative Beamforming for Wireless Ad Hoc Networks
    IEEE Transactions on Signal Processing, 2008
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a medium access control-physical (MAC-PHY) cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each collaborating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. Analyses of the average beampattern, networking performance, and symbol error probability corresponding to the proposed scheme are provided.

  • A High-Throughput Cross-Layer Scheme for Distributed Wireless Ad Hoc Networks
    arXiv: Information Theory, 2007
    Co-Authors: Athina P. Petropulu, Lun Dong, H. Vincent Poor
    Abstract:

    In wireless ad hoc networks, distributed nodes can collaboratively form an antenna array for long-distance communications to achieve high energy efficiency. In recent work, Ochiai, et al., have shown that such collaborative beamforming can achieve a statistically nice beampattern with a narrow main lobe and low sidelobes. However, the process of collaboration introduces significant delay, since all collaborating nodes need access to the same information. In this paper, a technique that significantly reduces the collaboration overhead is proposed. It consists of two phases. In the first phase, nodes transmit locally in a random access fashion. Collisions, when they occur, are viewed as linear mixtures of the collided packets. In the second phase, a set of cooperating nodes acts as a distributed antenna system and beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex number, which is independently computed by each cooperating node, and which enables separation of the collided packets based on their final destination. The scheme requires that each node has global knowledge of the network coordinates. The proposed scheme can achieve high throughput, which in certain cases exceeds one.

  • Cooperative Beamforming and Power Control
    2007 Conference Record of the Forty-First Asilomar Conference on Signals Systems and Computers, 2007
    Co-Authors: S.m. Betz, H.v. Poor, Athina P. Petropulu
    Abstract:

    This work presents an energy efficient, low-overhead scheme for cooperative beamforming in ad hoc networks. Collaborating nodes retransmit local signals to faraway destinations, multiplying the received Analog Waveform by a complex weight chosen (in a distributed fashion) to maximize the received SNR. The improvement in SNR is explicitly derived for a large number of cooperating nodes.

  • CISS - A High-Throughput Cross-Layer Scheme for Distributed Wireless Ad Hoc Networks
    2007 41st Annual Conference on Information Sciences and Systems, 2007
    Co-Authors: Athina P. Petropulu, Lun Dong, H.v. Poor
    Abstract:

    In wireless ad hoc networks, distributed nodes can collaboratively form an antenna array for long-distance communications to achieve high energy efficiency. In recent work, Ochiai, et al., have shown that such collaborative beamforming can achieve a statistically nice beampattern with a narrow main lobe and low side lobes. However, the process of collaboration introduces significant delay, since all collaborating nodes need access to the same information. In this paper, a technique that significantly reduces the collaboration overhead is proposed. It consists of two phases. In the first phase, nodes transmit locally in a random access fashion. Collisions, when they occur, are viewed as linear mixtures of the collided packets. In the second phase, a set of cooperating nodes acts as a distributed antenna system and beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex number, which is independently computed by each cooperating node, and which enables separation of the collided packets based on their final destination. The scheme requires that each node has global knowledge of the network coordinates. The proposed scheme can achieve high throughput, which in certain cases exceeds one.

  • GLOBECOM - Cooperative Beamforming for Wireless Ad Hoc Networks
    IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a MAC-PHY cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each cooperating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. An analysis of the symbol error probability corresponding to the proposed scheme is provided.

Lun Dong - One of the best experts on this subject based on the ideXlab platform.

  • A Cross-Layer Approach to Collaborative Beamforming for Wireless Ad Hoc Networks
    IEEE Transactions on Signal Processing, 2008
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a medium access control-physical (MAC-PHY) cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each collaborating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. Analyses of the average beampattern, networking performance, and symbol error probability corresponding to the proposed scheme are provided.

  • A High-Throughput Cross-Layer Scheme for Distributed Wireless Ad Hoc Networks
    arXiv: Information Theory, 2007
    Co-Authors: Athina P. Petropulu, Lun Dong, H. Vincent Poor
    Abstract:

    In wireless ad hoc networks, distributed nodes can collaboratively form an antenna array for long-distance communications to achieve high energy efficiency. In recent work, Ochiai, et al., have shown that such collaborative beamforming can achieve a statistically nice beampattern with a narrow main lobe and low sidelobes. However, the process of collaboration introduces significant delay, since all collaborating nodes need access to the same information. In this paper, a technique that significantly reduces the collaboration overhead is proposed. It consists of two phases. In the first phase, nodes transmit locally in a random access fashion. Collisions, when they occur, are viewed as linear mixtures of the collided packets. In the second phase, a set of cooperating nodes acts as a distributed antenna system and beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex number, which is independently computed by each cooperating node, and which enables separation of the collided packets based on their final destination. The scheme requires that each node has global knowledge of the network coordinates. The proposed scheme can achieve high throughput, which in certain cases exceeds one.

  • CISS - A High-Throughput Cross-Layer Scheme for Distributed Wireless Ad Hoc Networks
    2007 41st Annual Conference on Information Sciences and Systems, 2007
    Co-Authors: Athina P. Petropulu, Lun Dong, H.v. Poor
    Abstract:

    In wireless ad hoc networks, distributed nodes can collaboratively form an antenna array for long-distance communications to achieve high energy efficiency. In recent work, Ochiai, et al., have shown that such collaborative beamforming can achieve a statistically nice beampattern with a narrow main lobe and low side lobes. However, the process of collaboration introduces significant delay, since all collaborating nodes need access to the same information. In this paper, a technique that significantly reduces the collaboration overhead is proposed. It consists of two phases. In the first phase, nodes transmit locally in a random access fashion. Collisions, when they occur, are viewed as linear mixtures of the collided packets. In the second phase, a set of cooperating nodes acts as a distributed antenna system and beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex number, which is independently computed by each cooperating node, and which enables separation of the collided packets based on their final destination. The scheme requires that each node has global knowledge of the network coordinates. The proposed scheme can achieve high throughput, which in certain cases exceeds one.

  • GLOBECOM - Cooperative Beamforming for Wireless Ad Hoc Networks
    IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007
    Co-Authors: Lun Dong, Athina P. Petropulu, H.v. Poor
    Abstract:

    Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a MAC-PHY cross-layer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access time-slotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received Analog Waveform to one or more faraway destinations. This step requires multiplication of the received Analog Waveform by a complex weight, which is independently computed by each cooperating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. An analysis of the symbol error probability corresponding to the proposed scheme is provided.

Bruce A. Wooley - One of the best experts on this subject based on the ideXlab platform.

  • A 700-MHz switched-capacitor Analog Waveform sampling circuit
    IEEE Journal of Solid-State Circuits, 1994
    Co-Authors: Gunther Haller, Bruce A. Wooley
    Abstract:

    Analog switched-capacitor memory circuits are suitable for use in a wide range of applications where Analog Waveforms must be captured or delayed, such as the recording of pulse echo events and pulse shapes. Analog sampling systems based on switched-capacitor techniques offer performance superior to that of flash A/D converters and charge-coupled devices with respect to cost, density, dynamic range, sampling speed, and power consumption. This paper proposes an architecture with which sampling frequencies of several hundred megahertz can be achieved using conventional CMOS technology. Issues concerning the design and implementation of an Analog memory circuit based on the proposed architecture are presented. An experimental two-channel memory with 32 sampling cells in each channel has been integrated in a 2-/spl mu/m CMOS technology with poly-to-poly capacitors. The measured nonlinearity of this prototype is 0.03% for a 2.5 V input range, and the memory cell gain matching is 0.01% rms. The dynamic range of the memory exceeds 12 b for a sampling frequency of 700 MHz. The power dissipation for one channel operated from a single +5 V supply is 2 mW. >