miercuri, 23 noiembrie 2011

Scurt istoric despre Acces point

Wireless access point

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Industrial Wireless Access Point
In computer networking, a wireless access point (WAP) is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards. The WAP usually connects to a router (via a wired network), and can relay data between the wireless devices (such as computers or printers) and wired devices on the network.
Industrial grade WAPs are rugged, with a metal cover and a DIN rail mount. During operations they can tolerate a wider temperature range, high humidity and exposure to water, dust, and oil. Wireless security includes: WPA-PSK, WPA2, IEEE 802.1x/RADIUS, WDS, WEP, TKIP, and CCMP (AES) encryption. Unlike some home consumer models, industrial wireless access points can also act as a bridge, router, or a client.

[edit] Introduction

Linksys 802.11g Wireless Access Point
embedded RouterBoard 112 with U.FL-RSMA pigtail and R52 mini PCI Wi-Fi card widely used by wireless Internet service providers (WISPs) across the world
Prior to wireless networks, setting up a computer network in a business, home, or school often required running many cables through walls and ceilings in order to deliver network access to all of the network-enabled devices in the building. With the creation of the Wireless Access Point, network users are now able to add devices that access the network with few or no cables. Today's WAPs are built to support a standard for sending and receiving data using radio frequencies rather than cabling. Those standards, and the frequencies they use are defined by the IEEE. Most WAPs use IEEE 802.11 standards.

[edit] Common WAP applications

A typical corporate use involves attaching several WAPs to a wired network and then providing wireless access to the office LAN. The wireless access points are managed by a WLAN Controller which handles automatic adjustments to RF power, channels, authentication, and security. Further, controllers can be combined to form a wireless mobility group to allow inter-controller roaming. The controllers can be part of a mobility domain to allow clients access throughout large or regional office locations. This saves the clients time and administrators overhead because it can automatically re-associate or re-authenticate.
A hotspot is a common public application of WAPs, where wireless clients can connect to the Internet without regard for the particular networks to which they have attached for the moment. The concept has become common in large cities, where a combination of coffeehouses, libraries, as well as privately owned open access points, allow clients to stay more or less continuously connected to the Internet, while moving around. A collection of connected hotspots can be referred to as a lily-pad network.
The majority of WAPs are used in Home wireless networks.[citation needed] Home networks generally have only one WAP to connect all the computers in a home. Most are wireless routers, meaning converged devices that include the WAP, a router, and, often, an ethernet switch. Many also include a broadband modem. In places where most homes have their own WAP within range of the neighbors' WAP, it's possible for technically savvy people to turn off their encryption and set up a wireless community network, creating an intra-city communication network although this does not negate the requirement for a wired network.
A WAP may also act as the network's arbitrator, negotiating when each nearby client device can transmit. However, the vast majority of currently installed IEEE 802.11 networks do not implement this, using a distributed pseudo-random algorithm called CSMA/CA instead.

[edit] Wireless access point vs. ad hoc network

Some people confuse Wireless Access Points with Wireless Ad Hoc networks. An Ad Hoc network uses a connection between two or more devices without using a wireless access point: the devices communicate directly when in range. An Ad Hoc network is used in situations such as a quick data exchange or a multiplayer LAN game because setup is easy and does not require an access point. Due to its peer-to-peer layout, Ad Hoc connections are similar to Bluetooth ones and are generally not recommended for a permanent installation.
Internet access via Ad Hoc networks, using features like Windows' Internet Connection Sharing, may work well with a small number of devices that are close to each other, but Ad Hoc networks don't scale well. Internet traffic will converge to the nodes with direct internet connection, potentially congesting these nodes. For internet-enabled nodes, Access Points have a clear advantage, with the possibility of having multiple access points connected by a wired LAN.

marți, 22 noiembrie 2011

tema mea pentru lucrarea de atestat

                                                         iPhone

           Compania americană Apple a lansat iPhone, un terminal mobil care combină caracteristicile unui telefon, ale playerului muzical iPod şi funcţii de mesagerie instant.
Telefonul iPhone de la Apple este ultima fita la momentul actual si include optiuni si functii de o calitate excelenta cu un design indraznet si provocator. iPhone este un telefon foarte popular cu un ecran mare de tip touch screen pe care se afla toate tastele de care ai nevoie pentru al putea folosi.
Carcasa are dimensiunile 115 x 61 x 11.6 mm, cantareste 135 grame, iar culorile pe care le include sunt un negru stralucitor bine finisat si o culoare alba la fel de stralucitoare si sofisticata. Telefonul de la Apple are un ecran sensibil la atingere cu o multitudine de culori ce reda imagini foarte clare si de o calitate exceptionala pe ecranul care masoara 3.5 inchi si o rezolutie de 320×48.
iPhone este disponibil in doua variante de memorie, de 4GB si 8GB. Pe langa aceasta memorie inclusa, iPhone mai include o baterie ce ii da posibilitatea utilizatorului sa asculte muzica in continuu tip de 16 ore, iar timpul de vorbire este de aproximativ 5 ore.
Telefonul de la Apple are o agenda telefonica organizata foarte bine si permite adaugarea unei poze fiecarui contact din agenta. Agenda telefonica se poate accesa din meniul principal al telefonului si utilizatorul poate efectua apelul catre numarul ales apasand detaliile contactului pe ecranul sensibil. In timpul apelului, userul are posiblitatea sa puna apelul in asteptare, sa initieze un alt apel, sa umble in agenta sau meniul telefonului si sa faca o conferinta telefonica cu mai multi utilizatori, indiferent de marca telefonului.
Frumosul iPhone Apple are o camera foto/video integrata ce permite captura de imagini si videoclipuri la o calitate de 2 megapixeli. Telefonul are incluse multe optiuni si functii necesare pentru a configura dupa bunul plac capturile foto/video. Utilizatorul se va bucura si se va simti bine cu tastatura tip QWERTY direct pe ecranul sensibil al telefonului Apple, ce permite scrierea foarte rapida de mesaje de tip text (SMS), mesaje multimedia (MMS) si desigur mesaje e-mail. La capitolul e-mail utilizatorul se poate bucura de toate facilitatile pe care le are un client de e-mail adevarat, precum: interfata prietenoasa, atasamente de imagini sau alte fisiere si multele optiuni care sunt pregatite de a fi descoperite.

luni, 17 octombrie 2011

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stecher norma europeana, prize norme SUA, China, cu 2 lamele sau 3 lamele sau 3 pini laptop