Search results for "Real-time computing"
showing 10 items of 366 documents
Improved heuristics for the regenerator location problem
2014
Telecommunication systems use optical signals to transmit information. The strength of a signal in an optical network deteriorates and loses power as it goes farther from the source, mainly due to attenuation. Therefore, to enable the signal to arrive its intended destination with good quality, it is necessary to regenerate the signal periodically using regenerators. These components are relatively expensive and therefore it is desirable to deploy as few of them as possible in the network. In the regenerator location problem (RLP), we are given an undirected graph, positive edge lengths, and a parameter specifying the maximum length that a signal can travel before its quality deteriorates a…
Pervasive access to MRI bias artifact suppression service on a grid.
2009
Bias artifact corrupts magnetic resonance images in such a way that the image is afflicted by illumination variations. Some of the authors proposed the Exponential Entropy Driven - Homomorphic Unsharp Masking (E2D-HUM) algorithm that corrects this artifact without any a priori hypothesis about the tissues or the Magnetic Resonance image modality. Moreover, E2D-HUM does not care about the body part under examination and does not require any particular training task. People who want to use this algorithm, which is Matlab-based, have to set their own computers in order to execute it. Furthermore, they have to be Matlab-skilled to exploit all the features of the algorithm. In our work we propos…
A vision agent for mobile robot navigation in time-variable environments
2002
We present an architecture for mobile robot navigation based on Bayesian networks. The architecture allows a robot to plan the correct path inside an environment with dynamic obstacles. Interactions between the robot and the environment are based on a powerful vision agent. The results of simulations, showing the effectiveness of the approach, are described.
Tracking control of network distributed systems in presence of variable time delay and loss of information
2006
This paper deals with the control of network distributed systems which has been at the centre of interest in a wide area of research in the last few year. The control of such systems is very difficult because the communication networks inevitably introduce variable time delays and possible lost of samples. In particular, it is proposed an extension of the approach, derived in the contest of the optimal stochastic regulator problem [1], [2], to the remote tracking problem considering a distributed control system in which the signals from the transducers to the controller and from the controller to the actuator are transmitted through a communication network with variable delays and possible …
Velocity estimation in wideband mobile stations equipped with multiple antennas
2009
©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Article also available from publisher: http://dx.doi.org/10.1109/VETECS.2009.5073907 A new method is proposed for estimating the velocity of wideband mobile stations (MSs) equipped with multiple antennas. The MS speed is determined using the well-known relationship between the direction-of-arrivals (DOAs) and the Doppler frequency shifts experienced by the mult…
An Embedded Real-Time Lane-Keeper for Automatic Vehicle Driving
2008
Automatic vehicle driving involves several issues, such as the capability to follow the road and keep the right lane, to maintain the distance between vehicles, to regulate vehiclepsilas speed, to find the shortest route to a destination. In this paper a real-time automatic lane-keeper is proposed. The main features of the system are the lane markers location process as well as the computation of the vehiclepsilas steering lock. The above techniques require high elaboration speed to execute, check and complete an operation before a prearranged time. Clearly if system processing exceeds the deadline, the whole operation became meaningless or, in the meantime, the vehicle can reach a critical…
Dynamic Packet Bundling for VoIP Transmission Over Rel'7 HSUPA with 10ms TTI Length
2007
In this paper, the system level optimization of the voice over IP transmission in the HSUPA system, configured with a 10 ms TTI length, is analyzed. The study considers the release 7 improvements to HSUPA, in terms of the DPCCH gating concept. A dynamic activated MAC layer bundling of two VoIP packets in a single frame is proposed and compared against the single packet per frame transmission by means of quasi-static system level simulations.
VoIP end-to-end performance in HSPA with packet age aided HSDPA scheduling
2008
In this paper, we present an enhanced VoIP scheduling for the high speed downlink packet access (HSDPA) in UMTS, which takes the age of the VoIP packet into account. The downlink capacity can be significantly improved by this way, especially for shorter uplink transmission delay. In order to quantify the achievable performance improvement, we present results obtained from extensive system-level uplink and downlink simulations. Inter alia, it is shown that using the proposed scheme can lead to an increase in the downlink cell capacity of up to 16%. By applying the proposed method, the downlink performance can be improved considerably while the uplink performance remains the same, which ensur…
Optimal configuration for size-based burst assembly algorithms at the edge node for video traffic transmissions over OBS networks
2008
Optical burst switching (OBS) has been proposed to be a technology for implementing the next generation optical Internet. In this architecture, burst assembly algorithms have an important influence in the pattern traffic that characteristic this sort of optical networks. On the other hand, traffic coming from new applications (such as video on demand, Voice over IP, online gaming or Grid computing) that have real time and bandwidth constraints, has been experimented a rapid increment. Consequently, we consider important to evaluate the performance of traffic from real time applications over OBS networks. In this paper, we evaluate the effects of implementing a size-based burst assembly sche…
Effect and optimization of burst assembly algorithms for video traffic transmissions over OBS networks
2008
Optical burst switching (OBS) has been proposed to be a technology for implementing the next generation optical Internet. In this architecture, burst assembly algorithms have an important influence in the traffic pattern that characterizes this sort of optical networks. On the other hand, traffic coming from new applications (such as video on demand, Voice over IP, online gaming or Grid services) that have real time and bandwidth constraints has been experimented a rapid increment. Consequently, we consider important to evaluate the performance of the real time traffic over OBS networks. In this paper, we evaluate the video transmissions performance (MPEG4/RTP/UDP) over OBS networks, for bo…