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Virtual prototyping for large scalable systems such as networks and services are inherently expensive. On the other hand, extensive multi-domain simulation and virtual prototyping based design can be a beneficial from quality of design perspective. Thus detailed prototyping for a system under design is often a question of design economics. In this paper, we create a cost modeling framework (MUDCOM)...
Switching fabric is a hardware mechanism used inside packet switches and routers to provide an interconnection among I/O ports and possibly a CPU. The ideal switching fabric scales to handle a high data rate on a given port, and scales to handle many ports. Because practical switching fabrics cannot achieve the ideal, a set of architectures has been created of which each represents a trade off in...
The Web services technology enables communication, distributed computation and interoperability in heterogeneous environments. Although the technology is well specified and supported by the programming tools, it is still not widely used. Some of the main reasons are the difficulties which the end users have in searching an adequate Web service to get the required data. Even if found, the Web service...
Noise introduces a fundamental limit on the performance of any communication system. Satellite communication systems are particularly susceptible to noise because of their inherent low received power. During the link budget calculations, noises of the equipment and line loss have to be considered. An alternative, but equivalent way of expressing the noisiness of the equipment and line loss is through...
New and more dynamic services cause significant changes in the traffic distribution of today's transport networks. Thus it is a crucial challenge for network providers to dimension their networks appropriately to be able to satisfy the demands. This paper investigates the traffic portion of entirely uncertain demand requests that do not allow any forecast. We develop mathematical programs to minimize...
The paper presents the designing principles of a management infrastructure for monitoring the capabilities of different network interface cards (gigabit Ethernet, Endace), both for traffic generation and capturing at reception. This evaluation is useful to asses the goodness of captured traffic analysis and QoS performance measurements, using PC based platforms. The idea was to implement the communication...
In order to harmonize providing of IP services and applications by new commercial telecommunication networks and emerging mobile ad hoc networks, tending to be free, some symbiosis is investigated. The way has been already shown by next generation network concept and its interworking with infrastructure wireless LAN. In every fair symbiosis a compromises are required. Telecommunication networks could...
Electromagnetic fields can generate interference on intersystem wiring and cabling. Often this interconnection is in the form of cables and other forms of transmission lines. The simplest model for the system interconnections is a two wire transmission line. Even such a simple case is complex when the wavelength approaches the spacing between the conductors. In such a case one needs to use the full...
The radiation hazard (RADHAZ) survey is commonly done using field strength probes. These probes are inherently wideband and thus non-selective, what makes them a good choice for quick wideband surveys. On the other hand, this characteristic presents a problem when trying to discriminate signals in a multifrequency environment. The most commonly used diode-based probes have another significant drawback:...
This paper presents a study on transmission opportunity (TXOP) mechanism of the new MAC protocol described in the IEEE 802.11e supplement to the standard. A simple algorithm for dynamic configuration of TXOP limit is proposed for the contention channel access mode, called enhanced distributed channel access (EDCA). The proposed scheme aims to define dynamic rules for TXOP duration adjustment in multimode...
We teach electromagnetics as part of a general education course in physics (for non science majors) in which we relate physics to societal issues. The course covers the effects of electromagnetic radiation on human beings. This discussion is limited to at most one class room period (about 50 minutes) usually less. There are several important conceptual issues that must be covered before such a presentation...
Internet shoppers have become widespread comprising 89.1 % of all Internet users in Japan. Moreover, the leakage of personal information from shopping service providers causes a social problem, and requirements for personal information protection are increasing these days. An Internet shopping system is proposed to prevent leaking personal information such as name, home address, age, or gender using...
IP telephony has many advantages over traditional PSTN telephony. These advantages are mostly manifested in the possibility of implementing many new services as well as in the network capacity saving. The focus of this paper is the IP network transfer capacity savings analysis. IP network completely replaces the PSTN network. Also, the influence of the voice activity detection technique and VoIP packet...
High definition (HD) is showing an increasing popularity not only among professional and high cost video communication systems, but also among consumer devices. The aim of this paper is to investigate the adoption of HD in H.264/AVC video codecs for videoconference applications, where real time constraints, like short time delay, must agree with low complexity and computational costs. In order to...
This paper deals with the problem of designing good rate-variable LDPC codes for wireless applications, where fast link adaptation is required in order to maximize the system efficiency. In particular, we show that the so-called "pseudo-puncturing" strategy, recently introduced, can be used as a valid alternative to more conventional solutions, by ensuring good performance while maintaining...
In this paper, we propose a frequency domain (FD) MMSE equalizer for M-ary bi-orthogonal keying direct sequence UWB (MBOK DS-UWB) systems considered as a PHY proposal for high-speed wireless communication in IEEE 802.15.3a. The conventional FD MMSE equalization scheme has a structural limit due to insertion of the cyclic prefix (CP) in all transmit packets, but the proposed scheme is able to equalize...
In forest fire protection systems 24 hour surveillance is of most importance. Real time data must be acquired to react fast enough to suppress fire occurrence or to minimize damage made by forest fires. In forest fire monitoring systems, usually a large area must be controlled. Real time data has to be collected and processed in time. When the amount of data reaches critical volume, modern software...
The rapid spread of new radio access technologies, the ever increasing requirements for security, as well as the required capability for the final users to experience continuous connectivity and uninterrupted services of IP applications as they move about from one access network to another, has stimulated the technical and scientific community to investigate future evolution scenarios for 3G networks,...
Low-density parity-check (LDPC) codes are among the best channel codes known today and are in discussion for current and future communications standards. LDPC codes can be efficiently modeled by Tanner-graphs. In this paper, we present a novel hardware-efficient 2-vector design method of such graphs. We show communications performance results for an exemplary code created by this approach and corresponding...
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