作者:
S. GyoriHigh Speed Networks Laboratory
Department of Computer Science and Information Theory Budapest University슠of슠Technology슠and슠Economics Hungary
The problem of signature coding for a multiple access OR channel is studied. For the binomial model of the activity of the users, the Kautz-Singleton code and a random code are compared. The minimal code length of the...
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The problem of signature coding for a multiple access OR channel is studied. For the binomial model of the activity of the users, the Kautz-Singleton code and a random code are compared. The minimal code length of the random code is proved to be better than the existing bounds.
In this paper, the Intelligent Space concept is applied for helping disabled or blind persons in crowded environments such as train stations, or airports. The main contribution of this paper is a general mathematical ...
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In this paper, the Intelligent Space concept is applied for helping disabled or blind persons in crowded environments such as train stations, or airports. The main contribution of this paper is a general mathematical (fuzzy-neuro) description of obstacle avoidance method (walking habit) of moving objects (human beings) in a limited area scanned by the Intelligent Space. A mobile robot with extended functions is introduced as a mobile haptic interface, which is assisted by the Intelligent Space. The mobile haptic interface can guide and protect a blind person in a crowded environment with the help of the Intelligent Space. The Intelligent Space learns the obstacle avoidance method (walking habit) of dynamic objects (human beings) by tracing their movements and helps to the blind person to avoid the collision. The prototype of the mobile haptic interface and simulations of some basic types of obstacle avoidance method (walking habit) are presented.
Intelligent Space is a space which has distributed sensory intelligence and is equipped with actuators. The various devices of sensory intelligence cooperate with each other autonomously, and the whole space has high ...
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Intelligent Space is a space which has distributed sensory intelligence and is equipped with actuators. The various devices of sensory intelligence cooperate with each other autonomously, and the whole space has high intelligence, where we can easily interact with computers and robots, and get useful services from them. The most important sensors are video cameras achieving stereo vision, where stereo matching is necessary. This paper presents an artificial neural network for the adjustment of two cameras in order to picture the same spot for means of stereoscopic vision. The two cameras are in a master-slave relationship, where the optical center of the slave camera is adjusted to picture the same point as the optical center of the master camera. The task is performed by a biologically inspired artificial neural network, which can be embedded in an analog neural hardware to produce a real time solution for camera control in stereo vision that is faster than existing solutions.
The analysis, design aspects and numerical results of a current controlled three-phase space vector modulated (SVM) voltage source converter (VSC) are presented. The aim of the current controller of VSC is to track th...
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The analysis, design aspects and numerical results of a current controlled three-phase space vector modulated (SVM) voltage source converter (VSC) are presented. The aim of the current controller of VSC is to track the balanced three-phase sinusoidal reference currents. The current controller includes a complex saturation function in order to avoid overmodulation in the SVM. Due to this strong nonlinearity the study leads to rather unexpected system states. An approximate Poincare" map is derived using stroboscopic sampling with the modulation period of the SVM. Selecting eigenvalues of the system linearized around the desired fixed point is not sufficient to the proper operation. Other stable fixed points or limit cycles can appear. Chaotic states also can develop in the unstable region of the desired fixed point. The main objectives arc to develop the tools for describing the nonlinear behavior, for designing the digital PI controller and to present numerical results.
This paper presents a performance analysis of high-speed downlink packet access (HSDPA) for TCP/IP applications in WCDMA systems with smart packet dispatching (SPD). The focus is on energy efficiency over burst-error ...
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This paper presents a performance analysis of high-speed downlink packet access (HSDPA) for TCP/IP applications in WCDMA systems with smart packet dispatching (SPD). The focus is on energy efficiency over burst-error correlated fading channels. The fading-channel characterization thereof is due to low user mobility of the primarily targeted environments for HSDPA applications. Using theoretical analysis and simulation, we show that in burst-error correlated fading channels adapting the time instant of scheduling/dispatching retransmission to fading-channel conditions: (i) significantly reduces the number of retransmissions; and (ii) helps closing the gap of bad channel states allowing the system to operate with much lower fade margin or transmit-power. It thus improves the efficiency of resource utilization in HSDPA. This method is referred to as SPD. In our modeling, we study the impact of fading based on fade duration statistics. The effects of diversity, mobility, and QoS constraints (such as timer for discarding out-of-date packets) are taken into account. The results are used to develop simple and energy-efficient adaptive SPD mechanisms.
In today's networks there is a convergence to an integrated IP-based network. lETF's mobile IP handles global macromobility in the IP based infocommunication networks. It is, however, not adapted to micromobil...
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In today's networks there is a convergence to an integrated IP-based network. lETF's mobile IP handles global macromobility in the IP based infocommunication networks. It is, however, not adapted to micromobility environment; in this local mobility management there are several proposals both for IPv4 and IPv6. These approaches use local entities to support mobility in a well-defined area (domain), and hide the movements inside the domain from mobile IP. Future communication networks will transport not only voice calls but also other multimedia traffic. This type of data is sensible for packet delay, delay variation, packet loss, etc. To meet the requirements of users transmitting such data through the network we have to support better quality of service. In this paper we introduce an efficient solution for improving quality of service in cellular IP micromobility domains. We also show simulation results for our new method.
In this paper we propose a method to linearize a nonlinear dynamic system: the nonlinear distortion is reduced, and the linear dynamics are corrected to a flat amplitude and linear phase in a user defined frequency band.
In this paper we propose a method to linearize a nonlinear dynamic system: the nonlinear distortion is reduced, and the linear dynamics are corrected to a flat amplitude and linear phase in a user defined frequency band.
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