What is wi fi зва

What Is Wi-Fi?

Wi-Fi is a wireless networking technology that allows devices such as computers (laptops and desktops), mobile devices (smart phones and wearables), and other equipment (printers and video cameras) to interface with the Internet. It allows these devices—and many more—to exchange information with one another, creating a network. Internet connectivity occurs through a wireless router. When you access Wi-Fi, you are connecting to a wireless router that allows your Wi-Fi-compatible devices to interface with the Internet.

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What does Wi-Fi mean?

Wi-Fi is not an acronym; it is a brand name created by a marketing firm that’s meant to serve as an interoperability seal for marketing efforts.

How does Wi-Fi work?

On the technical side, the IEEE 802.11 standard defines the protocols that enable communications with current Wi-Fi-enabled wireless devices, including wireless routers and wireless access points. Wireless access points support different IEEE standards. Each standard is an amendment that was ratified over time. The standards operate on varying frequencies, deliver different bandwidth, and support different numbers of channels.

What is a wireless access point?

A wireless access point (AP) allows wireless devices to connect to the wireless network. Having a Cisco wireless network makes it easy to bring new devices online and provides flexible support to mobile workers.
What a wireless access point does for your network is similar to what an amplifier does for your home stereo. An access point takes the bandwidth coming from a router and stretches it so that many devices can go on the network from farther distances away. But a wireless access point does more than simply extend Wi-Fi. It can also give useful data about the devices on the network, provide proactive security, and serve many other practical purposes.

What is a wireless router?

Wireless routers are commonly found in homes. They’re the hardware devices that Internet service providers use to connect you to their cable or xDSL Internet network. A wireless router is sometimes referred to as a wireless local area network (WLAN) device. A wireless network is also called a Wi-Fi network. A wireless router combines the networking functions of a wireless access point and a router. Read more about wireless routers.

What is a desktop Wi-Fi router?

The most common way for users to connect to the Internet wirelessly is with a desktop wireless (Wi-Fi) router. These routers look like small boxes with multiple short antennas to help broadcast the signal throughout a home or workplace. The farther a user is from the base Wi-Fi router, the weaker the signal. So multiple wireless routers, called range extenders, usually are placed throughout the workspace. Wi-Fi range extenders, placed in an array, boost or extend Internet coverage.

What is a mobile hotspot?

A mobile hotspot is a common feature on smartphones with both tethered and untethered connections. When you turn on your phone’s mobile hotspot, you share your wireless network connection with other devices that can then access the Internet.

What is portable Wi-Fi hotspot?

A portable Wi-Fi hotspot is a mobile hotspot obtained through a cell phone carrier. It’s a small device that uses cellular towers that broadcast high-speed 3G or 4G broadband signals. Multiple devices, like iPads and laptops, can then connect wirelessly to the device, which in turn seamlessly connects to the Internet where ever you travel. Similar to a cell phone, the portable hotspot’s monthly cost is based on the data usage plan you select. A portable Wi-Fi hotspot is a more reliable way to access the Internet than searching for static public Wi-Fi hotspots.

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Презентации / 1-2 Wireless Intro

• Безопасность – ограничения . • Потребности бизнеса – анализ рисков ( экономия денежная и временная ) Учет рисков • Отказ / Отклонить ( Не произойдет ) • Принять ( Не влияет сильно ) • Передать ( на Out Source / Страхование ) • Снизить / Расшарить ( Поддержка производителя , защита от ..)

Телефония и WiFi • VoIP + WiFi • 1) Через Public mobile • 2) Через корпоративную систему через WiFi • Роуминг ?? В IP- сети ? • GSM – соединения • IP – пакетная передача . Connection less + Best Effort

• Идентификаторы и их приобретение ??

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Особенности • Оптимизированная и автоматизированная сеть – учет интерференции • Как быть с видео ? Multicast? • Функции аналитики • Сеть WiFi не должна быть отдельной , а должна быть полностью интегрированной в проводную сеть . • Единая точка аналитики и управления • Единая точка выгрузка трафика

• Что нужно для обмена по радиосреде ? • Передатчик / приемник / механизмы передачи • A, f , фаза • F=2.4 ГГц – скорость ?

What is Wi-Fi? • Что нужно для обмена по радиосреде ? • Передатчик / приемник / механизмы передачи • A, f , фаза • F=2.4 ГГц – скорость ? • Канал определенной ширины . • 20 – 40 – 80

What is Wi-Fi? • Wi-Fi networks use radio technologies based on IEEE 802.11 standards to provide secure, reliable, fast wireless connectivity, typically within a limited area such as a home or campus. • A Wi-Fi network can connect electronic devices to each other, to the Internet, and to wired networks. • Wi-Fi networks operate primarily in the unlicensed 2.4 and 5 GHz radio bands, and most of the times in both bands (dual-band) now. • Unlicensed is good from the perspective that it is “free” spectrum and anyone can use it. • It is not good from the perspective that, due to its common shared use, the spectrum tends to be crowded, sometimes causing interference among devices.

9607 1997 – 2 mbps of data rate = 1 SD video flow max . (level 2: 352×288, 30 img/sec, Extended profile H.264) 2013 – 870 mbps = 400+ SD video flows, or 50+ HD video flows (Level 3.1: 1280 × 720, 30 img/sec, Extended profile – 14mbps peak) IEEE 802.11ax (160MHz)

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Презентации / 1-2 Wireless Intro

• Безопасность – ограничения . • Потребности бизнеса – анализ рисков ( экономия денежная и временная ) Учет рисков • Отказ / Отклонить ( Не произойдет ) • Принять ( Не влияет сильно ) • Передать ( на Out Source / Страхование ) • Снизить / Расшарить ( Поддержка производителя , защита от ..)

Телефония и WiFi • VoIP + WiFi • 1) Через Public mobile • 2) Через корпоративную систему через WiFi • Роуминг ?? В IP- сети ? • GSM – соединения • IP – пакетная передача . Connection less + Best Effort

• Идентификаторы и их приобретение ??

T??

Особенности • Оптимизированная и автоматизированная сеть – учет интерференции • Как быть с видео ? Multicast? • Функции аналитики • Сеть WiFi не должна быть отдельной , а должна быть полностью интегрированной в проводную сеть . • Единая точка аналитики и управления • Единая точка выгрузка трафика

• Что нужно для обмена по радиосреде ? • Передатчик / приемник / механизмы передачи • A, f , фаза • F=2.4 ГГц – скорость ?

What is Wi-Fi? • Что нужно для обмена по радиосреде ? • Передатчик / приемник / механизмы передачи • A, f , фаза • F=2.4 ГГц – скорость ? • Канал определенной ширины . • 20 – 40 – 80

What is Wi-Fi? • Wi-Fi networks use radio technologies based on IEEE 802.11 standards to provide secure, reliable, fast wireless connectivity, typically within a limited area such as a home or campus. • A Wi-Fi network can connect electronic devices to each other, to the Internet, and to wired networks. • Wi-Fi networks operate primarily in the unlicensed 2.4 and 5 GHz radio bands, and most of the times in both bands (dual-band) now. • Unlicensed is good from the perspective that it is “free” spectrum and anyone can use it. • It is not good from the perspective that, due to its common shared use, the spectrum tends to be crowded, sometimes causing interference among devices.

9607 1997 – 2 mbps of data rate = 1 SD video flow max . (level 2: 352×288, 30 img/sec, Extended profile H.264) 2013 – 870 mbps = 400+ SD video flows, or 50+ HD video flows (Level 3.1: 1280 × 720, 30 img/sec, Extended profile – 14mbps peak) IEEE 802.11ax (160MHz)

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Part 1. Introduction to WiFi

If you’ve been in an airport, coffee shop, library or hotel recently, chances are you’ve been right in the middle of a wireless network. Many people also use wireless networking, also called WiFi or 802.11 networking, to connect their computers at home, and some cities are trying to use the technology to provide free or low-cost Internet access to residents. In the near future, wireless networking may become so widespread that you can access the Internet just about anywhere at any time, without using wires.

WiFi has a lot of advantages. Wireless networks are easy to set up and inexpensive. They’re also unobtrusive ─ unless you’re on the lookout for a place to use your laptop, you may not even notice when you’re in a hotspot. In this article, we’ll look at the technology that allows information to travel over the air. We’ll also review what it takes to create a wireless network in your home.

First, let’s go over a few WiFi basics.

Part 2. What Is WiFi?

A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. Here’s what happens:

1. A computer’s wireless adapter translates data into a radio signal and transmits it using an antenna.
2. A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.

The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer’s wireless adapter.

The radios used for WiFi communication are very similar to the radios used for walkie-talkies, cell phones and other devices. They can transmit and receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s. But WiFi radios have a few notable differences from other radios:

• They transmit at frequencies of 2.4 GHz or 5 GHz. This frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions. The higher frequency allows the signal to carry more data.
• They use 802.11 networking standards, which come in several flavors:

• 802.11a transmits at 5 GHz and can move up to 54 megabits of data per second. It also uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique that splits that radio signal into several sub-signals before they reach a receiver. This greatly reduces interference.
• 802.11b is the slowest and least expensive standard. For a while, its cost made it popular, but now it’s becoming less common as faster standards become less expensive. 802.11b transmits in the 2.4 GHz frequency band of the radio spectrum. It can handle up to 11 megabits of data per second, and it uses complementary code keying (CCK) modulation to improve speeds.
• 802.11g transmits at 2.4 GHz like 802.11b, but it’s a lot faster ─ it can handle up to 54 megabits of data per second. 802.11g is faster because it uses the same OFDM coding as 802.11a.
• 802.11n is the newest standard that is widely available. This standard significantly improves speed and range. For instance, although 802.11g theoretically moves 54 megabits of data per second, it only achieves real-world speeds of about 24 megabits of data per second because of network congestion. 802.11n, however, reportedly can achieve speeds as high as 140 megabits per second. The standard is currently in draft form ─ the Institute of Electrical and Electronics Engineers (IEEE) plans to formally ratify 802.11n by the end of 2009.

Other 802.11 standards focus on specific applications of wireless networks, like wide area networks (WANs) inside vehicles or technology that lets you move from one wireless network to another seamlessly.

WiFi radios can transmit on any of three frequency bands. Or, they can «frequency hop» rapidly between the different bands. Frequency hopping helps reduce interference and lets multiple devices use the same wireless connection simultaneously.

As long as they all have wireless adapters, several devices can use one router to connect to the Internet. This connection is convenient, virtually invisible and fairly reliable; however, if the router fails or if too many people try to use high-bandwidth applications at the same time, users can experience interference or lose their connections.

Next, we’ll look at how to connect to the Internet from a WiFi hotspot.

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