Real-time Low Power Research Articles

Localization in 2D Using Beacons of Low Frequency Magnetic Field

In this work we propose methods for object localization in 2D using beacons of low frequency quasi-static magnetic field. From a practical point of view, localization in 2D is sufficient for many applications, requiring much less calculations than in 3D, making it more robust and easier to implement in real-time low power applications. The low frequency magnetic field may penetrate foliage, soil, buildings, and many other types of media. This is an important advantage over traditional localization methods such as sonar or radar, where effective operation requires line-of-sight. Another advantage of the low frequency magnetic fields is that there is no direct influence by bad weather conditions and diurnal variations. Opposite to traditional electromagnetic methods, where operational range is usually more than a wavelength, low frequency induction approach results in a relatively limited localization range. Each beacon comprises a coil generating a magnetic field of a unique frequency in the ULF band. The generated magnetic fields are sensed by a search-coil magnetometer. The magnetometer readings are processed to estimate the magnitude and phase of the received beacons signals, which are used to localize the magnetometer. For a moving object, we propose to combine localization together with tracking algorithm using a data fusion approach. The proposed methods have been tested using numerous computer simulations, showing accurate localization results. A prototype was developed and used in field experiments, validating simulation results. The good accuracy together with a simple implementation makes the proposed methods attractive to many real-time low power field applications.

Low Power Industrial Weigh Measuring Device

This paper presents ultra-low power measuring system for portable industrial jack with weigh measurement. Paper describes real-time low power system issues and suggests solution for small battery measurement systems. The main aim of the research work is the implementation of a prototype low power measuring device. Measured data from sensor are collected and processed in embedded system. Data are displayed in real time on LCD display after signal processing.

Joint Algorithm-Architecture Optimization of CABAC

This paper uses joint algorithm and architecture design to enable high coding efficiency in conjunction with high processing speed and low area cost. Specifically, it presents several optimizations that can be performed on Context Adaptive Binary Arithmetic Coding (CABAC), a form of entropy coding used in H.264/AVC, to achieve the throughput necessary for real-time low power high definition video coding. The combination of syntax element partitions and interleaved entropy slices, referred to as Massively Parallel CABAC, increases the number of binary symbols that can be processed in a cycle. Subinterval reordering is used to reduce the cycle time required to process each binary symbol. Under common conditions using the JM12.0 software, the Massively Parallel CABAC, increases the bins per cycle by 2.7 to 32.8× at a cost of 0.25 to 6.84% coding loss compared with sequential single slice H.264/AVC CABAC. It also provides a 2× reduction in area cost, and reduces memory bandwidth. Subinterval reordering reduces the critical path delay by 14 to 22%, while modifications to context selection reduces the memory requirement by 67%. This work demonstrates that accounting for implementation cost during video coding algorithms design can enable higher processing speed and reduce hardware cost, while still delivering high coding efficiency in the next generation video coding standard.

An Enhanced Reservation-Based MAC Protocol for IEEE 802.15.4 Networks

The IEEE 802.15.4 Medium Access Control (MAC) protocol is an enabling standard for wireless sensor networks. In order to support applications requiring dedicated bandwidth or bounded delay, it provides a reservation-based scheme named Guaranteed Time Slot (GTS). However, the GTS scheme presents some drawbacks, such as inefficient bandwidth utilization and support to a maximum of only seven devices. This paper presents eLPRT (enhanced Low Power Real Time), a new reservation-based MAC protocol that introduces several performance enhancing features in comparison to the GTS scheme. This MAC protocol builds on top of LPRT (Low Power Real Time) and includes various mechanisms designed to increase data transmission reliability against channel errors, improve bandwidth utilization and increase the number of supported devices. A motion capture system based on inertial and magnetic sensors has been used to validate the protocol. The effectiveness of the performance enhancements introduced by each of the new features is demonstrated through the provision of both simulation and experimental results.

A Significance of VLSI Techniques for Low Power Real Time Systems

In microelectronics design, power consumption, speed of operation, are crucial constraints. Propagation delay of circuit component has an impact on such factors. Pipelining and parallel processing strategies are utilized for desirable propagation delays and hence for clock and throughput variation respectively. To some extent variation in propagation delay is responsible for power consumption reduction. In this paper, pipelining and parallel processing concepts are analyzed with reference to task scheduling in real time system. Power consumption and speed of operation issues of such systems are analyzed.

An all binary sub-pixel motion estimation approach and its hardware architecture

Motion estimation (ME) is the most computationally intensive part of a video coding system. Therefore it is very important to reduce its computational complexity. In this paper, a novel all-binary approach for reducing the computational complexity of sub-pixel accurate ME is proposed. An efficient hardware architecture for the proposed all-binary sub-pixel accurate motion estimation approach is also presented. The proposed hardware architecture has significantly low hardware complexity and therefore very low power consumption. It can process 720p video frames at 30 fps in a pipelined fashion together with the integer ME hardware. Therefore, it can be used in real-time low power video coding systems required by many mobile consumer electronics devices.

A high-quality digital filter instrument

A high-quality real-time low power dissipation 12-bit low-pass digital-filter instrument is described. It is a hardware version of a recently proposed multirate ladder structure which can be implemented entirely without digital multipliers. The frequency response of the filter is user programmable and is determined by an operating sequence stored in a read-only memory. A numerical technique is described for determining the operating sequence corresponding to a particular low-pass response. Measured frequency responses are shown for four different cutoff frequencies between 2 and 5.5 kHz) for the fifth-order filter instrument.