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Real-time Services (real-time + services)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

Ultralow-power CMOS/SOI circuit technology

ELECTRICAL ENGINEERING IN JAPAN, Issue 3 2008
Yuichi Kado
Abstract We have introduced an example of a system that embodies the concept of a ubiquitous communication service and explained the importance of low power consumption in the communicator that will serve as the bridge between the real world and the network for real-time services in which sensor data is acquired every second. An effective solution to the problem of high energy efficiency is to employ the synergy of combining low-voltage analog circuit technology and FD-SOI devices. Taking advantage of that synergy to reduce the power consumption of the communicator during operation to about 10 mW and employing intermittent operation with an activity rate of less than l% would make it possible to support operation for 1 year or more with a commercial coin-type lithium battery. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(3): 38,43, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20543 [source]

On the efficiency of PGPS-based packet and cell switching technologies for traffic with guaranteed delay

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003
Fulvio Risso
Circuit switching, suited to providing real-time services due to the low and fixed switching delay, is not cost effective for building integrated services networks because it is based on static allocation of resources which is not efficient with bursty data traffic. Moreover it cannot handle flows that are not integer multiple of 64,Kb/s, preventing the usage of low bit rate codecs. This work explores the most suitable alternatives to the circuit switching technology (i.e. packet/cell switching) from the efficiency point of view, assuming that a PGPS scheduler is deployed in the network nodes. The paper defines an index to measure the efficiency of packet telephony, i.e. the volume of real-time traffic with deterministically guaranteed quality plus the amount of data carried related to the amount of network resources used. Furthermore it determines the maximum efficiency obtainable by packet networks, compares different network technologies and explores the problems of the deploying of low bit-rate codecs. Copyright © 2003 AEI. [source]

Modelling multi-dimensional QoS: some fundamental constraints

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2004
Nelson X. Liu
Abstract In this paper, we model multi-dimensional QoS in a unified framework, and study some fundamental constraints from the network and the traffic on realizing multiple QoS goals. Multi-dimensional QoS requirements are quantitatively represented using a QoS region. Based on the theory of effective bandwidths, the framework connects the throughput, the delay, and the loss rate in a uniform formula. Important traffic and network factors, namely, the burst size and the link speed, are involved. With this framework, it is found that the burst size sets hard limit on the QoS region that can be achieved, and that the matching between the link speed and the node processing power can greatly improve the limit. It is also made clear that while pure load imbalance among links does not affect the QoS region, the heterogeneities of burst size or link speed may severely degrade the QoS performance. Applying the theory to real-time services in differentiated services architecture, we show it provides a useful tool for QoS prediction and network dimensioning. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Using a multiple priority reservation MAC to support differentiated services over HFC systems,

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2002
J. D. Angelopoulos
Abstract The successful commercial deployment of Hybrid Fibre/Coaxial (HFC) access networks in the residential market has so far been driven by demand for faster Internet access and the prospects of a host of new services based on real-time voice and video. To sustain their growth rates and compete with alternative approaches, such as ADSL, they must be enhanced with the capability to efficiently handle quality-intensive real-time services. The new multi-service paradigm mandates isolation of traffic classes, conditioning of entering traffic and preventive control in addition to traditional closed-loop control. The differentiated services (DiffServ) architecture with its relevant traffic control tools and the bundling of behaviour aggregates is particularly suited to the H/W-based MAC of HFC systems. It constitutes a suitable framework enabling the support of proliferating real-time voice- and video-based services while aligning the system to the emerging Internet strategy of scalable service differentiation. The implementation of such a solution in the ACTS 327AROMA research project is presented in this paper. The performance of the system is evaluated using computer simulation. Copyright © 2002 John Wiley & Sons, Ltd. [source]