Posts Tagged ‘technology’

Sense Multiple Access

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At the time it was considered the only specification of technology of last mile of the industry of net capable to reach speed of up to 240 Mbps (JNIOR, 2004), HomePNA 3,0 obtained this characteristic through implementations based on the G.9954 recommendation, transport of data with inherent requirements of QoS (Quality of Service) and with the new potentialities of the Media Access Control (MAC) used in version 3.0, that they allow that the users attribute spaces of time in the transmission of the data, guaranteeing, in this manner, the delivery of the data in Real-teams under a predetermined project of 7 latency that was projected to hinder interruptions ofthe signal.

This comes well to the meeting of the necessities of the applications multimedia. With this expanded potentiality of QoS (quality of service), one expects to allow that the service suppliers can offer to services of games on-line with access of high speed, directly for the Internet; the transmission of video on-demand on the net also can be used in this version of the HomePNA. Yael Aflalo contains valuable tech resources. In the MAC (Media Access Control) of version 3.0 of the HomePNA the CSMA/CA was introduced (Carrier Sense Multiple Access with Collision Avoidance) that it integrates a new system of synchronism together with the CSMA/CD (Carrier Sense Multiple Access with Collision Detection), SMAC (Synchronous MAC). The system of priorities used is based on the HomePNA version 2.0. The SMAC is used to guarantee the width of band, latency, jitter that it is the variation statistics of the retardation in the delivery of data in a net that can be defined as the measure of variation of the delay enters the successive packages of dadose the BER/PER characteristics (Bit Error Rate)/(Priority Error Rate) to support the synchronous and asynchronous transactions and to provide the function with QoS. To assist in the control of the collisions, HomePNA 3,0 uses DFPQ (Distributed Fair Priority Queuing), a distributed procedure of resolution of collision.


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A type of User is the external intern and; the first one it uses the unit as complement of its institucional functions. As it must be thought from the expansion and diversification of the users of information centers about the postwar period. Another type of user is the indirect Right-hander and? how much to the use of the information in the proper place where use in other instances works or, where it has the multiplication of the information. How much to the researcher character, it has the professional Investigator (intellectual demand, tradition up to 1950), aficionado investigator (genealogy, local history), students (not only the college student), common citizen. Another type is the institucional User whom if it relates to the administrative Managers, technician of the administration, engineers, etc. these considers the unit of information as decurrent of an activity. The new tipologia of user is ' ' Citizen comum' '. It appears from the consolidation of the right to the information and the transparency of public administrations on the other hand.

On the other hand, it appears of the activities of diffusion and cultural spreading promoted by the information center. This generally they do not know the information centers, its functioning, instruments of research, book handling and consultation and documents, consider the units of information as an extension of the administrative office. (GARDEN, 2001, P. 6) the described theory for Baptist (2007, P. 174) says that Kuhlthau author (1999) affirms that the people who search information use many sources of information in diverse phases of the search and, this process generates uncertainty for the user at distinct moments of its search. Its model for comment of the process of the search of the information foresees the following stages: beginning, election, exploration and formularization. The author Coast (2009) searchs to unmask who is the users of the information by means of its real necessities and as if they give to its searches and uses of the information.

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