89,324 research outputs found
Using carry-save adders in low-power multiplier blocks
For a simple multiplier block FIR filter design, we compare the effects on power consumption of using direct versus transposed direct forms, tree versus linear structures and carry-save (CS) versus carry-ripple (CR) adders (for which multiplier block algorithms have been designed). We find that tree structures offer power savings, as expected, as does transposition in general but not always. Selective use of CS adders is shown to offer power savings provided that care is taken with their deployment. Our best result is with a direct form CWCS hybrid.
The need for new multiplier-block design algorithms is
identified
State of the art: iterative CT reconstruction techniques
Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limitations in CT imaging
Power Efficient MISO Beamforming for Secure Layered Transmission
This paper studies secure layered video transmission in a multiuser
multiple-input single-output (MISO) beamforming downlink communication system.
The power allocation algorithm design is formulated as a non-convex
optimization problem for minimizing the total transmit power while guaranteeing
a minimum received signal-to-interference-plus-noise ratio (SINR) at the
desired receiver. In particular, the proposed problem formulation takes into
account the self-protecting architecture of layered transmission and artificial
noise generation to prevent potential information eavesdropping. A
semi-definite programming (SDP) relaxation based power allocation algorithm is
proposed to obtain an upper bound solution. A sufficient condition for the
global optimal solution is examined to reveal the tightness of the upper bound
solution. Subsequently, two suboptimal power allocation schemes with low
computational complexity are proposed for enabling secure layered video
transmission. Simulation results demonstrate significant transmit power savings
achieved by the proposed algorithms and layered transmission compared to the
baseline schemes.Comment: Accepted for presentation at the IEEE Wireless Communications and
Networking Conference (WCNC), Istanbul, Turkey, 201
A Dynamic Real-time Scheduling Algorithm for Reduced Energy Consumption
In embedded real-time systems, Dynamic Power Management (DPM) techniques have traditionally focused on reducing the dynamic power dissipation that occurs when a CMOS gate switches in a processor. Less attention has been given to processor leakage power or power consumed by I/O devices and other subsystems. I/O-based DPM techniques, however, have been extensively researched in non-real-time systems. These techniques focus on switching I/O devices to low power states based on various policies and are not applicable to real-time environments because of the non-deterministic nature of the policies. The challenge in conserving energy in embedded real-time systems is thus to reduce power consumption while preserving temporal correctness. To address this problem, we introduce three scheduling algorithms of increasing complexity: Energy-Aware EDF (EA-EDF), Enhanced Energy-Aware EDF (EEA-EDF) and Slack Utilization for Reduced Energy (SURE). The first two algorithms are relatively simple extensions to the Earliest Deadline First (EDF) scheduling algorithm that enable processor, I/O device, and subsystem energy conservation. The SURE algorithm utilizes slack to create a non-work-conserving approach to reducing power consumption. An evaluation of the three approaches shows that all three yield significant energy savings with respect to no DPM technique. The actual savings depends on the task set, shared devices, and the power requirements of the devices. When the cost of switching power states is low, the EA-EDF and EEA-EDF algorithms provide remarkable power savings considering their simplicity. In general, however, the higher the energy cost to switch power states, the more benefit SURE provides
A Dynamic Real-time Scheduling Algorithm for Reduced Energy Consumption
In embedded real-time systems, Dynamic Power Management (DPM) techniques have traditionally focused on reducing the dynamic power dissipation that occurs when a CMOS gate switches in a processor. Less attention has been given to processor leakage power or power consumed by I/O devices and other subsystems. I/O-based DPM techniques, however, have been extensively researched in non-real-time systems. These techniques focus on switching I/O devices to low power states based on various policies and are not applicable to real-time environments because of the non-deterministic nature of the policies. The challenge in conserving energy in embedded real-time systems is thus to reduce power consumption while preserving temporal correctness. To address this problem, we introduce three scheduling algorithms of increasing complexity: Energy-Aware EDF (EA-EDF), Enhanced Energy-Aware EDF (EEA-EDF) and Slack Utilization for Reduced Energy (SURE). The first two algorithms are relatively simple extensions to the Earliest Deadline First (EDF) scheduling algorithm that enable processor, I/O device, and subsystem energy conservation. The SURE algorithm utilizes slack to create a non-work-conserving approach to reducing power consumption. An evaluation of the three approaches shows that all three yield significant energy savings with respect to no DPM technique. The actual savings depends on the task set, shared devices, and the power requirements of the devices. When the cost of switching power states is low, the EA-EDF and EEA-EDF algorithms provide remarkable power savings considering their simplicity. In general, however, the higher the energy cost to switch power states, the more benefit SURE provides
Resource Allocation for Secure Communication in Systems with Wireless Information and Power Transfer
This paper considers secure communication in a multiuser multiple-input
single-output (MISO) downlink system with simultaneous wireless information and
power transfer. We study the design of resource allocation algorithms
minimizing the total transmit power for the case when the receivers are able to
harvest energy from the radio frequency. In particular, the algorithm design is
formulated as a non-convex optimization problem which takes into account
artificial noise generation to combat potential eavesdroppers, a minimum
required signal-to-interference-plus-noise ratio (SINR) at the desired
receiver, maximum tolerable SINRs at the potential eavesdroppers, and a minimum
required power delivered to the receivers. We adopt a semidefinite programming
(SDP) relaxation approach to obtain an upper bound solution for the considered
problem. The tightness of the upper bound is revealed by examining a sufficient
condition for the global optimal solution. Inspired by the sufficient
condition, we propose two suboptimal resource allocation schemes enhancing
secure communication and facilitating efficient energy harvesting. Simulation
results demonstrate a close-to-optimal performance achieved by the proposed
suboptimal schemes and significant transmit power savings by optimization of
the artificial noise generation.Comment: 7 pages, 5 figures, and 1 table. Submitted for possible conference
publicatio
- …