نتایج جستجو برای: wireless
تعداد نتایج: 108490 فیلتر نتایج به سال:
Wireless sensor networks are often located in areas where access to them is difficult or dangerous. Today, in wireless sensor networks, cluster-based routing protocols by dividing sensor nodes into distinct clusters and selecting local head-clusters to combine and send information of each cluster to the base station and balanced energy consumption by network nodes, get the best performance ...
سنتز کننده های فرکانسی دیجیتالی مستقیم که به ddfs معروف هستند مدارهای الکترونیکی دیجیتال هستند که برای تولید سیگنال های سینوسی با گستره وسیع فرکانسی مورد استفاده قرار می گیرند و در سیستم های مخابراتی دیجیتال مدرن ، رادار ، روباتیک و سیستم های wireless و ... نقش مهمی را ایفا می کنند[1]. از مزایای این سنتز کننده رنج فرکانسی وسیع، سوئیچینگ فرکانس فاز پیوسته، دقت فرکانسی خوب ،خلوص طیفی بالا و توانا...
Transmission opportunity limit and contention window are two influenced parameters in accessing the media in the networks based IEEE 802.11e standard. In these networks, every wireless station by setting of its contention window value, determines the chance of access to wireless media. Furthermore, a transmission opportunity limit provides a period of transmission without contact for a station....
wireless sensor networks(wsn) have unique properties that distinguished them from other wireless networks and have special challenges. not-chargeable, not-changeable and limited power supplies of sensor nodes is the most important challenge of this networks, and if the power supply of node expired, a part of data maybe lost. because of the importance of covers in wireless sensors, in this work ...
the intelligent transportation system (its) provides wireless and mobile communication between vehicles and infrastructure to improve the safety of transportation and make the journey more enjoyable. this system consists of many fixed and mobile nodes (vehicles, trains, vessels, air planes), wireless and wired telecommunication technologies to exchange information between mobile nodes or betwee...
Wireless sensor networks have many applications in the real world and have been developed in various environments. But the limitations of these networks, including the limitations on the energy and processing power of the sensors, have posed many challenges to researchers. One of the major challenges is the security of these networks, and in particular the issue of authentication in the wireles...
The rapid advancement in wireless over wired has augmented the need for improving theQuality of Service (QoS) over such wireless links. However, the wireless ad hoc networkshave too low bandwidth, and establishing a QoS in these networks is a difficult issue. So,support of quality of service in ad hoc networks is the topical issue among the networkscience researchers. In this research we are go...
This paper proposes an analytical model for evaluating the performance of dense wavelength division multiplexing (DWDM) for all optical orthogonal frequency division multiplexing (AO-OFDM) optical wireless channel. The investigated performance for proposed system is evaluated for the parameters bit error rate (BER) and Q factor .The constellation diagrams, and bit error rate (BER) of the recei...
Wireless sensor networks are often located in areas where access to them is difficult or dangerous. Today, in wireless sensor networks, cluster-based routing protocols by dividing sensor nodes into distinct clusters and selecting local head-clusters to combine and send information of each cluster to the base station and balanced energy consumption by network nodes, get the best performance ...
Introduction: The "Wireless Sensor Network" based rehabilitation is one of the major issue in hospitals. The purpose of this study was to prioritization the criteria of wireless sensor networks in the rehabilitation supervision using the Fuzzy MCDM Approach. Methods: In this descriptive study, the population consisted of all doctors and nurses in Tehran Day's Hospital, with 210 people. From the...
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