Processing Power Requirements Research Articles

Application of Mixed-radix FFT Algorithms in Multi-band GNSS Signal Acquisition Engines

Due to their fast operation, Fast Fourier Transform (FFT)-based coarse signal synchronization methods are an attractive option for Global Navigation Satellite System (GNSS) receiver baseband signal processing. However, there are several reasons why the utility of FFT-based methods is dependent on understanding the trade-off between synchronization speed and the required processing power. Firstly, the new signals of the GNSS family, for instance Galileo and GPS modernization, employ longer period Pseudo Random Noise (PRN) codes and higher signal bandwidths, which demand FFTs of large transform lengths. Secondly, to gain an advantage in positioning performance, next generation receivers target multiple GNSS signals, and since each signal has its own code length (and hence a minimum sampling frequency), the receiver should accommodate FFT blocks of varying lengths. This paper discusses the requirements of FFT-based algorithms for such a multiband receiver and analyzes the application of primefactor and mixed-radix FFT algorithms. A novel way of factorizing different transform lengths into smaller transforms and then combining these smaller-point FFTs to compute the larger required FFTs is described. It is shown that the use of the proposed architecture reduces the computational load (or processor cycles) and increases the re-usability of the acquisition search engine to process different signals.

EFFICIENT COMBINED SCHEDULING OF HARD AND SOFT REAL-TIME TASKS IN MULTIPROCESSOR SYSTEMS UNDER A PROCESSING POWER-SHARE STRATEGY

Increasingly, real-time systems are being used in applications that contain tasks that have deadlines and require predictable performance. Many complex real-time applications require modern operating systems capable of scheduling multiple classes of tasks in an integrated way. These applications require scheduling that result in high utilization of available processing power to accommodate as many tasks as possible while satisfying the required deadlines of each task. In this paper, we propose a combined heuristic approach to schedule a set of independent soft and hard real-time tasks in multiprocessor computing systems. Each of these tasks is characterized by its arrival time, deadline and required processing power. The proposed approach distributes the total available processing power of any processor, if it is needed and possible, among more than one task, while ensuring that hard real-time tasks are given higher priority and enough processing power to meet deadlines. This strategy can be used as a tool to efficiently guide scheduling processes. In addition, it can help to optimize processor utilization and maintain higher success ratios by maximizing the schedulability of soft tasks without jeopardizing the schedulability of hard tasks.

An Efficient Unit-selection Method for Concatenative Text-to-speech Synthesis Systems

This paper presents a method for selecting speech units for polyphone concatenative speech synthesis, in which the simplification of procedures for search paths in a graph accelerated the speed of the unit-selection procedure with minimum effects on the speech quality. The speech units selected are still optimal; only the costs of merging the units on which the selection is based are less accurately determined. Due to its low processing power and memory footprint requirements, the method is suitable for use in embedded speech synthesizers.

A Fully Integrated SoC with Digital MAC Processor and Transceiver for Ubiquitous Sensor Network at 868/915 MHz

SUMMARY A single-chip ubiquitous sensor network (USN) systemon-a-chip (SoC) for small program memory size and low power has been proposed and integrated in a 0.18-µm CMOS technology. Proposed singlechip USN SoC is mainly consists of radio for 868/915 MHz, analog building block, complete digital baseband physical layer (PHY) and media access control (MAC) functions. The transceiver’s analog building block includes a low-noise amplifier, mixer, channel filter, receiver signal-strength indication, frequency synthesizer, voltage-controlled oscillator, and power amplifier. In addition, digital building block consists of differential binary phase-shift keying (DPSK) modulation, demodulation, carrier frequency offset compensation, auto-gain control, embedded 8-bit microcontroller, and digital MAC function. Digital MAC function supports 128 bit advanced encryption standard (AES), cyclic redundancy check (CRC), intersymbol timing check, MAC frame control, and automatic retransmission. These digital MAC functions reduce the processing power requirements of embedded microcontroller and program memory size by up to 56%. The cascaded noise figure and sensitivity of the overall receiver are 9.5 dB and −99 dBm, respectively. The overall transmitter achieves less than 6.3% error vector magnitude (EVM). The current consumption is 14 mA for reception mode and 16 mA for transmission mode.

Network intrusion detection through Adaptive Sub-Eigenspace Modeling in multiagent systems

Recently, network security has become an extremely vital issue that beckons the development of accurate and efficient solutions capable of effectively defending our network systems and the valuable information journeying through them. In this article, a distributed multiagent intrusion detection system (IDS) architecture is proposed, which attempts to provide an accurate and lightweight solution to network intrusion detection by tackling issues associated with the design of a distributed multiagent system, such as poor system scalability and the requirements of excessive processing power and memory storage. The proposed IDS architecture consists of (i) the Host layer with lightweight host agents that perform anomaly detection in network connections to their respective hosts, and (ii) the Classification layer whose main functions are to perform misuse detection for the host agents, detect distributed attacks, and disseminate network security status information to the whole network. The intrusion detection task is achieved through the employment of the lightweight Adaptive Sub-Eigenspace Modeling (ASEM)-based anomaly and misuse detection schemes. Promising experimental results indicate that ASEM-based schemes outperform the KNN and LOF algorithms, with high detection rates and low false alarm rates in the anomaly detection task, and outperform several well-known supervised classification methods such as C4.5 Decision Tree, SVM, NN, KNN, Logistic, and Decision Table (DT) in the misuse detection task. To assess the performance in a real-world scenario, the Relative Assumption Model, feature extraction techniques, and common network attack generation tools are employed to generate normal and anomalous traffic in a private LAN testbed. Furthermore, the scalability performance of the proposed IDS architecture is investigated through the simulation of the proposed agent communication scheme, and satisfactory linear relationships for both degradation of system response time and agent communication generated network traffic overhead are achieved.

Thermal integration of trigeneration systems

Trigeneration can be considered as a special case of the application of cogeneration systems where a fraction of the shaft work or residual heat is used for running a refrigeration system. This work focuses on trigeneration schemes where a gas turbine is used as a prime mover for power production and cooling is generated by a typical compression–refrigeration system. In most applications, a gas turbine will meet either the process power requirements or the heating needs, but it is unlikely that both would be satisfied simultaneously in the most efficient manner. The selection of the gas turbine that minimizes the heat losses to the ambient while supplying the required power can be readily accomplished by superimposing the turbine exhaust gas temperature profile to the process streams profile in a T vs enthalpy curve. This is because the maximum overall efficiency depends on the process heat and power demands and on the shape of the heat demand profile of the process. The use of the thermodynamic model helps to simulate the main components of the system and permits a fast and interactive way to design the optimum trigeneration scheme using the performance data of commercial gas turbines.

Efflcient implementation of MPEG-4 video encoder on RISC core

MPEG-4 simple profile video is being used as the video compression standard in mobile video communications. MPEG-4 video requires more computational power because of its high complexity. Currently, RISC cores are widely used in mobile applications because of their low power consumption. Design of fully standard-complaint MPEG-4 video encoder with real time performance on a RISC processor for embedded applications entails optimizations at all levels to the maximum extent possible. This paper describes in detail about the implementation of MPEG-4 simple profile video encoder on efficient RISC processor core requiring 50 Mega Cycles to encode QCIF resolution video at 15 frames per second with minimum processing power and memory requirements.

A stability analysis of a decentralized adaptive feedback active control system of sinusoidal sound in free space.

In some cases, the implementation of active control of sound in free space requires a large number of secondary sources and error sensors. In terms of control hardware, this may translate into considerable processing power requirement. A practical method to decrease processing power is to decentralize the control; that is, implement many single-input, single-output independent controllers operating simultaneously instead of a large multiple-input, multiple-output system. The main drawback of decentralized control is the risk of global instability. The purpose of this paper is to derive conditions under which globally stable control system behavior can be obtained in the case of adaptive feedback decentralized control for a sinusoidal disturbance. The main objective is to give practical conditions derived from the small gain theorem and the Nyquist criterion for the stability of the control system. These conditions only take into account the geometrical arrangement of the secondary sources and error sensors. This analysis involves a new parameter beta called "performance index," which is associated with both the convergence of the individual controllers and the global stability of the system. Simulation and experimental results are shown to illustrate the effectiveness of the developed analytical tools.

Optimum analog-to-digital converters for a laser speckle correlation-based displacement and strain sensor with optical preprocessing

We present a novel noncontact measurement procedure to determine displacements of and engineering strains within specimens at very high measurement rates. Appropriate hybrid optical and digital sig- nal processing can be employed to realize two dimensional (2D) corre- lation processing. Due to appropriate optical signal processing, the data acquisition can be performed in one dimension through CCD line-scan cameras. As a result, only 1D digital signal processing algorithms have to be executed and hence the processing power requirements decrease greatly. In this way, the measuring rates are substantially increased. It is shown that optimal Lloyd-Max quantizers implemented in the analog-to- digital converter (ADC) used in combination with a particular digital cor- relation algorithm are able to yield a further increase of the measurement rates compared with standard digital correlation techniques. © 2001 Soci-

Programmable implementations of xDSL transceiver systems

After a background on digital subscriber line (DSL) technology, this article evaluates the trade-offs between programmable and custom implementations of communications products with an emphasis on xDSL modems. These trade-offs include time to market, risk, flexibility, power consumption, and cost. A key issue is the processing power required to implement the modem. The article takes a detailed look at the processing power required to implement an ADSL or VDSL modem on a programmable platform. It is demonstrated that today's digital signal processors meet the processing power requirements for an ADSL modem, and it is estimated that the processing requirements of a VDSL modem will be met in the near future.

Broadband MPEG-2 Client with Network Configuration Capability

MPEG-2 is a standard for high quality-content compression and data delivery used in digital television and DVD. MPEG-2 is computationally complex but recently it has become possible to perform MPEG-2 decoding in software using multimedia instruction sets of modern microprocessors. This is an important step for the convergence of computers with television and entertainment. In this paper we describe operation and performance of a broadband video client which is MPEG-2 transport stream decoder with network interfaces, implemented on Sun UltraSparc processor using VIS multimedia instruction set. The decoder performs demultiplexing, synchronized video and audio decompression and display in realtime. It is implemented as a Netscape plug-in and it has flexible network interface allowing to configure it for different broadband networks which might be available: ATM PVC, SVC, IP over ATM and Fast Ethernet. Implementation of the decoder in multithreaded and multiprocessing environment is studied. Experimental data regarding the performance of the decoder in different conditions are presented and basing on them conclusions for the processing power requirements are formulated.

IMAGE: a low cost, low power video processor for high quality motion estimation in MPEG-2 encoding

A low cost low power architecture dedicated to perform high quality motion estimation on MPEG-2 CCIR 601 sequences is presented. The chip implements a new high performance motion estimation algorithm based on a modified genetic search strategy that can be enhanced by tracking motion vectors through successive frames. When tested on several sequences at different bit rates, the algorithm delivers nearly full search quality (less than -0.1 dB for a /spl plusmn/75 H/V search range) while decreasing the processing power to 0.5%. The proposed MIMD processor exposes software programmability at different levels allowing the user to define his own searching strategy and combine multiple chips in Master-Salve configuration to meet the required processing power. Moreover post-processing of motion vectors, computation of dual prime vectors for low delay coding and selection of macroblock prediction mode can be programmed on this architecture. A low power strategy was also developed that mainly relies on an adaptive clocking scheme and low power caches implementation. The chip has been integrated in a 0.35 /spl mu/m 5L CMOS technology on an area of 50 mm/sup 2/.

Efficient Multi-Resolution Multi-Stream Video Systems withStandard Codecs

The availability of international standards based video codecs for inexpensive platforms is reducing the cost of desk-top video systems to a level which makes their wide deployment possible. The current systems, however, are tuned for processing a single video stream only and their use in multiple video applications, such as continuous presence video teleconferencing and digital picture-in-picture, is difficult and inefficient. In this paper, we discuss two systems for efficient generation and display of multi-resolution, multiple compressed video material. Based on simple additions to standard codecs, both systems are capable of generating multiple bit streams corresponding to different resolutions of a single video source and they can decode such streams from multiple sources and display the resulting video sequences simultaneously. Both systems provide multiple video functionality to standard codecs with almost no extra memory or processing power requirements. Also, they make it possible for the users to customize the placement and size of their video windows, just as text and graphics windows can be manipulated.

Intelligent paging strategies for third generation mobile telecommunication systems

Location management procedures, in conjunction with the millions of users expected to subscribe to third generation mobile telecommunication systems, will generate a huge signaling load. In this paper, we propose a method which aims at the reduction of signaling overhead on the radio link produced by the paging procedure. The key idea is the application of a multiple step paging strategy which operates as follows: at the instance of a call terminating to a mobile user who roams within a certain location area, paging is initially performed in a portion of the location area (the paging area) that the so-called "paging related information" indicates. On no paging response, the mobile user is paged in the complementary portion of the location area-this phase can be completed in more than one (paging) step. Various "paging related information" elements (e.g. recent interaction information, high mobility flag, etc.) can be used and several "intelligent" paging strategies can be defined. Representative paging strategies are analyzed in terms of network performance and quality of service (paging signaling, paging delay, processing power requirements), via a simulation tool which models a realistic city area environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sofiware Partitioning for Distributed, Sequential, Pipelined Applications

Investigation into real-time performance analysis and allocation of system resources to meet throughout and response time requirements has resulted in a proposed methodology for structuring software for real-time distributed systems. A queueing network model is used to estimate real-time performance for alternative software partitions, and those partitions which can satisfy user performance requirements while requiring minimal resources are determined. The current work is limited to feed-forward, pipelined structures. Partition blocks are formed by merging user-specified modules, and the required processing power to meet user requirements is then determined. A two queue model, representing module service and communications, is analyzed using queueing network approximation. The results show that the optimal solution set can be determined using a branch and bound approach. An example of the application of the results to a real system is provided. The results have been implemented as a user-interactive software structuring tool.

Oxygen Transfer in Membrane‐Ceramic Composite Materials For Immobilized‐Cell Monolithic Reactors

A novel bioreactor concept is described for facilitated gas-liquid mass transfer, specifically oxygen supply, at low shear rates and low power input. The cross flow monolithic reactor is a single piece of ceramic consisting of continuous flow passages manifolded in a cross flow arrangement. Liquid medium circulates through the passages in one direction and gas circulates through the passages in an orthogonal direction; thus, the two streams are contacted across a large area of a porous ceramic, gas permeable membrane composite.A test cell was designed and used to measure the rate of oxygen transfer across such a composite. High oxygen transfer rates (6.62g O(2) x l(-1) x hr(-1)), with minimal power requirements (estimated below 5 x 10(-3) watts/l reactor volume), were found. This corresponds to a transfer efficiency of greater than 1000 kg O(2)/kW . hr, orders of magnitude greater than the values reported by Serieys, et al.(14) due to the low flow rates and low pressure drops required in a cross flow monolith. This contacting configuration could be employed with highly aerobic, immobilized-cell fermentations to enhance oxygen transfer rates with a parallel decrease of process power requirements.