WiMax technology: operating principle, equipment, areas of application. Wireless technologies: Wi-Fi and WiMAX

WiMAX is a telecommunications technology designed to provide wireless communication and data transmission over long distances for a large number of different devices (we are talking not only about base stations, but also about various devices: smartphones, laptops, tablets, etc.).

Developed as alternative telephone lines and DSL technology. Currently the maximum theoretical level of transmission speed achieved is 1 Gbit/s.

How Wimax works

It works on the principle of a traditional mobile network. That is, they are installed base stations, which form the wireless network coverage. This coverage provides continuous telecommunications in a certain area through a permanent radio channel in the microwave range.

How WiMAX works

User device automatically receives the signal from the nearest base station with a stronger signal in the “access zone”.

Distinguish fixed(for stationary devices) and mobile(for portable, moving in space) WiMAX standard.

Each of them has its own characteristics: primarily the operating frequency, as well as access methods and transfers.

Difference between wimax and wifi

The technologies have a lot in common, if we talk about the essence - transmitting data over a distance without the use of wires, cables, etc. using specific radio frequencies. However WiMax is superior Wi-Fi access speeds. Also is different large coverage, due to which it can be used as a backbone channel, which ultimately may make it possible to organize on their basis scalable urban networks with high access speeds.

They also differ in their areas of application, so they can work complementary to each other. It all depends on the target audience and the ability of operators to provide the technology. For WiMAX you need more powerful network infrastructure, which accordingly incurs large material costs for its construction and a longer payback period.

As you know, the Wi-Fi standard is 802.11, and the WiMAX standard is 802.16. Accordingly, there is a difference in their technical characteristics.

The significant difference is that radius of action Wi-Fi does not exceed 100 meters without obstacles (in everyday conditions this is 20-30 meters). If speak about WiMAX, then the maximum declared range 50 km(in reality 5-10 km), which is much more. It is advisable to use Wi-Fi to create local private networks. With WiMAX you can create regional networks. Only devices that support this standard and are equipped with the appropriate module can connect to this network.

Wi-Fi is used much more due to cheapness And you just settings.

Both technologies are easy to use and allow you to easily deploy and scale networks in the shortest possible time.

Why choose wimax

The future is WiMAX. Already now the mobile version allows you to work at speeds of up to 10 Mbit/s. You can use high-speed Internet anywhere – at home, in the car or at work. The connection is different reliability And quality. WiMAX provides universal wireless access for a wide range of devices.

In theory, everything is just fine, but in practice there are still problems with the implementation of the technology due to a shortage of frequency devices, an insufficient legislative framework and the high cost of setup. However, these flaws can be eliminated, and in the next decade, users will become more familiar with this technology, just as Wi-Fi technology conquered the wireless Internet in its time.

WiFi(English) Wireless Fidelity- “wireless precision”) is a trademark of the Wi-Fi Alliance for wireless networks based on the IEEE 802.11 standard.

Any equipment that complies with the IEEE 802.11 standard can be tested by the Wi-Fi Alliance and receive the appropriate certificate and the right to apply the Wi-Fi logo.

Figure 10. WiFi logo

Wi-Fi was created in 1991 by NCR Corporation/AT&T (later Lucent Technologies and Agere Systems) in Nieuwegein, the Netherlands. Products originally intended for point-of-sale systems were introduced to the market under the WaveLAN brand and provided data transfer rates of 1 to 2 Mbit/s.

Typically, a Wi-Fi network diagram contains at least one access point (the so-called infrastructure mode) and at least one client. It is also possible to connect two clients in point-to-point mode, when the access point is not used, and the clients are connected via network adapters “directly”. The access point transmits its network identifier (SSID) using special signaling packets at a speed of 0.1 Mbit/s every 100 ms. Therefore, 0.1 Mbit/s is the lowest data transfer speed for Wi-Fi. Knowing the network's SSID, the client can determine whether a connection to a given access point is possible. When two access points with identical SSIDs are within range, the receiver can choose between them based on signal strength data. The Wi-Fi standard gives the client complete freedom in choosing the criteria for the connection.

Advantages:

Allows you to deploy a network without laying cables, which can reduce the cost of network deployment and/or expansion. Places where cable cannot be installed, such as outdoors and buildings of historical value, can be served by wireless networks.
Allows mobile devices to access the network.
Wi-Fi devices are widely available in the market. Equipment compatibility is guaranteed through mandatory certification of equipment bearing the Wi-Fi logo.

Flaws:

Frequency range and operating restrictions vary from country to country. Many European countries allow two additional channels that are prohibited in the US; Japan has another channel at the top of the band, and other countries, such as Spain, prohibit the use of low-band channels. Moreover, some countries, such as Russia, Belarus and Italy, require registration of all Wi-Fi networks operating outdoors or require registration of the Wi-Fi operator.
In Russia, wireless access points, as well as Wi-Fi adapters with an EIRP exceeding 100 mW (20 dBm), are subject to mandatory registration. Decision of SCRF No. 04-03-04-003 dated December 6, 2004. approves the main technical characteristics of intra-office distribution zones (Appendix No. 1) and contains a list of distribution zones that are subject to registration in a simplified manner, that is, without issuing a permit to use radio frequencies (Appendix No. 2).
High energy consumption compared to other standards, which reduces battery life and increases the temperature of the device.
The most popular encryption standard, WEP, can be broken relatively easily even with the correct configuration (due to the weak strength of the algorithm). Although newer devices support the more advanced data encryption protocol WPA and WPA2, many older access points do not support it and require replacement. The adoption of the IEEE 802.11i (WPA2) standard in June 2004 made a more secure scheme available in new equipment. Both schemes require a stronger password than those typically assigned by users. Many organizations use additional encryption (such as a VPN) to protect against intrusion.
Wi-Fi has a limited range. A typical 802.11b or 802.11g home Wi-Fi router has a range of 45m indoors and 500m outdoors. A microwave or mirror placed between Wi-Fi devices will weaken the signal. The distance also depends on the frequency.
Overlapping signals from a closed or encrypted access point and an open access point operating on the same or adjacent channels may interfere with access to the open access point. This problem can occur when there is a high density of access points, for example, in large apartment buildings where many residents install their own Wi-Fi access points.
Incomplete compatibility between devices from different manufacturers or incomplete compliance with the standard may result in limited connection capabilities or reduced speed.
Reduced network performance during rain.
Equipment overload when transmitting small data packets due to the attachment of a large amount of service information.
Low suitability for applications that use real-time media streams (for example, the RTP protocol used in IP telephony): the quality of the media stream is unpredictable due to possible high losses during data transmission caused by a number of factors uncontrollable by the user (atmospheric interference, landscape and others, in particular those listed above). Despite this drawback, a lot of VoIP equipment based on 802.11b/g devices is produced, which is also aimed at the corporate segment: however, in most cases, the documentation for such devices contains a disclaimer stating that the quality of communication is determined by the stability and quality of the radio channel.

Use of technology:

Commercial access to Wi-Fi-based services is available in places such as Internet cafes, airports and coffee shops around the world (commonly referred to as Wi-Fi cafes), but their coverage can be considered spotty compared to cellular networks.

For industrial use, Wi-Fi technologies are currently offered by a limited number of suppliers. Thus, Siemens Automation & Drives offers Wi-Fi solutions for its SIMATIC controllers in accordance with the IEEE 802.11g standard in the free ISM band of 2.4 GHz and providing a maximum transmission speed of 11 Mbit/s. These technologies are used mainly to control moving objects and in warehouse logistics, as well as in cases where for some reason it is impossible to lay wired Ethernet networks.

WiMAX(English) W orldwideI interoperability forM icrowaveA access) is a telecommunications technology developed to provide universal, long-range wireless communications for a wide range of devices (from workstations and laptop computers to mobile phones). Based on the IEEE 802.16 standard, also called Wireless MAN.

The name "WiMAX" was created by the WiMAX Forum, an organization that was founded in June 2001 to promote and develop WiMAX technology. The forum describes WiMAX as “a standard-based technology that provides high-speed wireless network access as an alternative to leased lines and DSL.” Maximum speeds are up to 1 Gbps.

WiMAX is suitable for solving the following problems:

Connecting Wi-Fi access points to each other and to other segments of the Internet.
Providing wireless broadband access as an alternative to leased lines and DSL.
Providing high-speed data transmission and telecommunications services.
Creating access points that are not tied to geographic location.
Creation of WiMAX remote monitoring systems (monitring systems), as is the case in the system (SCADA)

WiMAX allows you to access the Internet at high speeds, with much greater coverage than Wi-Fi networks. This allows the technology to be used as “trunk channels”, a continuation of which are traditional DSL and leased lines, as well as local networks. As a result, this approach allows the creation of scalable high-speed networks within cities.

Fixed and mobile WiMAX option

The set of advantages is inherent to the entire WiMAX family, but its versions differ significantly from each other. The developers of the standard were looking for optimal solutions for both fixed and mobile applications, but it was not possible to combine all the requirements within one standard. Although a number of basic requirements are the same, the technology's focus on different market niches has led to the creation of two separate versions of the standard (or rather, they can be considered two different standards). Each of the WiMAX specifications defines its operating frequency ranges, bandwidth, radiation power, transmission and access methods, signal coding and modulation methods, principles of radio frequency reuse and other indicators. Therefore, WiMAX systems based on versions of the IEEE 802.16 e and d standard are practically incompatible. Brief characteristics of each version are given below.

802.16-2004 (also known as 802.16d and fixed WiMAX). The specification was approved in 2004. Orthogonal frequency division multiplexing (OFDM) is used and fixed access is supported in areas with or without line of sight. User devices are stationary modems for installation outdoors and indoors, as well as PCMCIA cards for laptops. In most countries, the 3.5 and 5 GHz bands are allocated for this technology. According to the WiMAX Forum, there are already about 175 implementations of the fixed version. Many analysts see it as a competing or complementary technology to wired DSL broadband.

802.16-2005 (also known as 802.16e and mobile WiMAX). The specification was approved in 2005. This is a new stage in the development of fixed access technology (802.16d). Optimized to support mobile users, the version supports a number of specific functions such as handover, idle mode and roaming. Scalable OFDM access (SOFDMA) is used; operation is possible with or without line of sight. The planned frequency ranges for Mobile WiMAX networks are: 2.3-2.5; 2.5-2.7; 3.4-3.8 GHz. Several pilot projects have been implemented around the world, including Scartel, which was the first to deploy its network in Russia. 802.16e's competitors are all third generation mobile technologies (eg EV-DO, HSDPA).

The main difference between the two technologies is that fixed WiMAX allows servicing only “static” subscribers, while mobile is focused on working with users moving at speeds of up to 120 km/h. Mobility means the presence of roaming functions and “seamless” switching between base stations when the subscriber moves (as happens in cellular networks). In a particular case, mobile WiMAX can also be used to serve fixed users

In general, WiMAX networks consist of the following main parts: base and subscriber stations, as well as equipment connecting the base stations with each other, with the service provider and with the Internet.

To connect the base station to the subscriber station, a high-frequency radio wave range from 1.5 to 11 GHz is used. Under ideal conditions, data exchange rates can reach 70 Mbit/s without requiring line-of-sight between the base station and the receiver.

As mentioned above, WiMAX is used both to solve the “last mile” problem and to provide network access to office and district networks.

Line-of-sight connections are established between base stations using the frequency range from 10 to 66 GHz, data exchange speeds can reach 140 Mbit/s. In this case, at least one base station is connected to the provider's network using classic wired connections. However, the greater the number of BSs connected to the provider’s networks, the higher the data transfer speed and reliability of the network as a whole.

The structure of networks of the IEEE 802.16 family of standards is similar to traditional GSM networks (base stations operate at distances of up to tens of kilometers; for their installation it is not necessary to build towers - installation on the roofs of houses is allowed, subject to the conditions of direct visibility between stations)

Mobile and fixed WiMAX networks in Russia are being built by:

Prestige Internet company under the Enforta brand (more than 80 major cities in Russia)
Scartel company under the Yota brand (Moscow, St. Petersburg, Ufa, Krasnodar, Sochi, Samara, Kazan, Chelyabinsk)
Comstar
Synterra
"NTK" (Vladivostok)
"New telecommunications" under the trademarks "WiTe" and "NEX3"
"Interproject" under the brand "Freshtel" (Tula, Novomoskovsk, Chekhov, Serpukhov)
"Trivon Networks" under the brand name "Virgin Connect",
JSC MediaSet company under the brand name “UnitLine”
Sovtest(Kursk)
DARS TELECOM (Ulyanovsk)
GLOBALFON (Ivanovo, Sochi, Kuznetsk)
NewCom (Tyumen)
as well as more than 20 regional Internet providers

Comparisons between WiMAX and Wi-Fi are not uncommon - the terms are similar, the names of the standards on which these technologies are based are similar (standards developed by IEEE, both begin with “802.”), and both technologies use a wireless connection and are used to connect to the Internet (data exchange channel). But despite this, these technologies are aimed at solving completely different problems.

Table 1.

Wireless standards comparison chart.

Wireless Standards Comparison Chart
Technology	Standard	Usage	Bandwidth	Radius of action	Frequencies
WiFi	802.11a	WLAN	up to 54 Mbit/s	up to 100 meters	5.0 GHz
WiFi	802.11b	WLAN	up to 11 Mbit/s	up to 100 meters	2.4 GHz
WiFi	802.11g	WLAN	up to 108 Mbit/s	up to 100 meters	2.4 GHz
WiFi	802.11n	WLAN	up to 300 Mbit/s (in the future up to 450 and then up to 600 Mbit/s)	up to 100 meters	2.4 - 2.5 or 5.0 GHz
WiMax	802.16d	WMAN	up to 75 Mbit/s	6-10 km	1.5-11 GHz
WiMax	802.16e	Mobile WMAN	up to 40 Mbit/s	1-5 km	2.3-13.6 GHz
WiMax	802.16m	WMAN, Mobile WMAN	up to 1 Gbit/s (WMAN), up to 100 Mbit/s (Mobile WMAN)	n/a (standard in development)	n/a (standard in development)
Bluetooth v. 1.1.	802.15.1	WPAN	up to 1 Mbit/s	up to 10 meters	2.4 GHz
Bluetooth v. 1.3.	802.15.3	WPAN	from 11 to 55 Mbit/s	up to 100 meters	2.4 GHz
UWB	802.15.3a	WPAN	110-480 Mbit/s	up to 10 meters	7.5 GHz
ZigBee	802.15.4	WPAN	from 20 to 250 Kbps	1-100 m	2.4 GHz (16 channels), 915 MHz (10 channels), 868 MHz (one channel)
Infrared port	IrDa	WPAN	up to 16 Mbit/s	from 5 to 50 centimeters, one-way communication - up to 10 meters

WiMAX stands for Worldwide Interoperability for Microwave Access or in Russian International Interoperability for Microwave Access. WiMAX technology is based on wireless communication standards that provide high-speed broadband communications over long distances for home (consumer) and business purposes.

WiMAX works on the principle of the orthogonal frequency division modulation method. This is 4th generation wireless mobile access technology.

The operating principle of WiMAX is similar to that of Wi-Fi. A computer or laptop equipped with WiMAX will receive data from the transmitting station using encrypted data keys. A minimum WiMAX system consists of a WiMAX transceiver tower and a WiMAX receiver. The WiMAX tower can provide coverage over a large area, while the WiMAX receiver can be a laptop or PCMCIA card. The tower station can be connected directly to the Internet using a high-speed bandwidth wireless link, a wired connection, or another tower using Line of Sight, Microwave link technologies.

WiMAX connection is available for residential areas through interface options such as RJ-4 Ethernet connection and RJ-11 telephone connection. For business applications, options include a T1/E1 interface with a 10/100 BT Ethernet connection. So, according to the above, WiMax technology is similar to Wifi, so what is the difference?

While Wi-Fi is based on the IEEE 802.11 standard, WiMAX is based on the IEEE 802.16 standard. The IEEE 802.11 standard is used to provide wireless local area network (WLAN) functionality for short-distance wireless communications. Popular versions: IEEE 802.11b, 802.11g and 802.11n. IEEE 802.16 is similar in architecture to IEEE 802.11, but differs in that it enables broadband wireless metropolitan area networks (WMANs). It uses a media access control (mac) as well as physical layer specifications that allow multiple physical layers. Popular versions are 802.16a, 802.16d and 802.16e.

Thus, one of the main differences between WiMAX and Wi-Fi is range. WiMAX provides both line-of-sight and out-of-sight data transmission. For line-of-sight data transmission using powerful antennas, a coverage area of up to 9,300 square kilometers can be achieved. With non-line of sight, WiMAX covers a radius of 50 kilometers. On the other hand, Wi-Fi is a means of wireless communication with a range of up to 30 meters for indoor applications and up to 100 meters for outdoor use. Unlike WiMAX, Wi-Fi provides effective communication only in the direct line of sight.

WiMAX and Wi-Fi also differ in operating frequencies and bandwidths. WiMAX technology in Line of sight mode has an operating frequency range of up to 66 GHz, and in Non-line of sight mode the operating frequency ranges from 2 to 11 GHz. In contrast, Wi-Fi operates in the unlicensed 2.4 GHz and 5 GHz bands. WiMAX networks have a bandwidth of 1.25 MHz to 20 MHz, while Wi-Fi networks have a fixed channel bandwidth of 20 MHz.

WiMAX supports full duplex communication with 256 FFT OFDM (Orthogonal Frequency Division Modulation) along with single carrier and 2048 FFTOFDM technology. On the other hand, Wi-Fi supports half-duplex communication with 52 FFT OFDM technology.

Wi-Fi can transfer data at a maximum speed of up to 54 megabits per second, while the speed for WiMAX can reach 70 megabits per second. The standard currently provides 40 megabits per second per wireless channel for both fixed and mobile applications. WiMAX can provide uplink speeds of 25 megabits per second and downlink speeds of 63 megabits per second. The updated version of WiMAX is expected to provide speeds of up to 1 gigabit per second.

These two technologies also differ in matters of data protection and cryptography. For example, Wi-Fi provides security methods such as Wireless Protected Access (WPA), Wireless Protected Access (WPA2), and Extensible Authentication Protocol (EAP). However, it does not yet have Quality of Service (QoS) management. WiMAX uses security protocols such as Privacy Key Management Protocol 2 (PKMP2), Extensible Authentication Protocol (EAP), and Extensible Encryption Standard (EAS). These protocols provide Quality of Service (QoS) protection for both audio and video streams. This feature allows service providers to manage network traffic based on the subscriber agreement and charge additional fees for quality of service (QoS) protection.

WiMAX appears to be a promising next-generation wireless technology with high data rates and wide coverage. It does not require line-of-sight for data exchange and can efficiently use bandwidth to transmit media such as real-time video. In simple words, using WiMAX, you can listen to music and watch high quality videos on your electronic device without any delay.

Wireless technologies (Wi-Fi, Bluetooth, WiMAX)

Computer science, cybernetics and programming

Currently, there are many wireless technologies, most often known to users by their marketing names such as WiFi WiMAX Bluetooth. 4 GHz operates many devices such as devices supporting Bluetooth, etc., and even microwave ovens, which worsens electromagnetic compatibility.

Wireless technologies subclass information technologies, serve to transmit information over a distance between two or more points, without requiring them to be connected by wires. Can be used to transmit informationinfrared radiation, radio waves , optical or laser radiation.

There are many wireless technologies available today, most commonly known to users by their marketing names such as Wi-Fi, WiMAX, Bluetooth . Each technology has certain characteristics that determine its scope of application.

1) Wi-Fi brand Wi-Fi Alliance for wireless networks based on the standard IEEE 802.11 . Under the abbreviation Wi-Fi (from the English phrase Wireless Fidelity, which can be literally translated as “high precision wireless data transmission”), a whole family of standards for transmitting digital data streams over radio channels is currently being developed.

Any equipment that meets the standard IEEE 802.11 , can be tested in Wi-Fi Alliance and receive the appropriate certificate and the right to apply the Wi-Fi logo.

Story

Wi-Fi was created in 1991 by NCR Corporation/AT&T (later Lucent Technologies and Agere Systems) in Nieuwegein, Netherlands . Products originally intended for point-of-sale systems were introduced to the market under the WaveLAN brand and provided data transfer rates of 1 to 2 Mbit/s. The creator of Wi-Fi Vic Hayes was on the team that participated in the development of standards such as IEEE 802.11b, IEEE 802.11a and IEEE 802.11g. In 2003, Vic left Agere Systems . Agere Systems was unable to compete on equal terms in difficult market conditions, despite the fact that its products occupied the niche of cheap Wi-Fi solutions. Agere's 802.11abg all-in-one chipset (codename: WARP) sold poorly and Agere Systems decided to exit the Wi-Fi market at the end 2004.

IEEE 802.11n standard was approved on September 11, 2009. Its use allows you to increase the data transfer rate almost four times compared to standard devices 802.11g (the maximum speed of which is 54 Mbps), subject to use in 802.11n mode with other 802.11n devices. Theoretically, 802.11n is capable of providing data transfer rates of up to 600 Mbps.

July 27, 2011 Institute of Electrical and Electronics Engineers(IEEE) released the official version of the standard IEEE 802.22 . Systems and devices that support this standard will allow you to transfer data at speeds of up to 22 Mb/s within a radius of 100 km from the nearest transmitter.

origin of name

The term "Wi-Fi" was originally coined as a play on words to attract the consumer's attention with a "hint" of Hi-Fi High Fidelity high accuracy). Despite the fact that at first the phrase “Wireless Fidelity” appeared in some WECA press releases, this wording has now been abandoned, and the term “Wi-Fi” is not deciphered in any way.

Principle of operation

Typically, a Wi-Fi network diagram contains at least one access points and at least one client . It is also possible to connect two clients inpoint-to-point (Ad-hoc), when the access point is not in use and clients connect vianetwork adapters"directly". The access point transmits its network ID ( SSID (English) Russian ) using special signaling packets at a speed of 0.1 Mbit/s every 100 ms. Therefore 0.1 Mbit/s is the smallestbaud ratefor Wi-Fi. Knowing the network SSID, the client can find out whether a connection to a given access point is possible. When two access points with identical SSIDs are within range, the receiver can choose between them based on signal strength data. The Wi-Fi standard gives the client complete freedom in choosing the criteria for connections . The operating principle is described in more detail in the official text of the standard.

However, the standard does not describe all aspects of building wireless local Wi-Fi networks. Therefore, each equipment manufacturer solves this problem in its own way, using those approaches that it considers the best from one point of view or another. Therefore, there is a need to classify methods for constructing wireless local networks.

Based on the method of combining access points into a single system, we can distinguish:

Autonomous access points (also called autonomous, decentralized, smart)
Access points operating under the control of a controller (also called “lightweight”, centralized)
Controllerless, but not standalone (managed without a controller)

Based on the method of organizing and managing radio channels, wireless local networks can be distinguished:

With static radio channel settings
With dynamic (adaptive) radio channel settings
With a “layered” or multilayer structure of radio channels

Benefits of Wi-Fi

Allows you to deploy a network without laying cable , which can reduce the cost of network deployment and/or expansion. Places where cable cannot be installed, such as outdoors and buildings of historical value, can be served by wireless networks.
Allows mobile devices to access the network.
Wi-Fi devices are widely available in the market. Equipment compatibility is guaranteed through mandatory certification of equipment bearing the Wi-Fi logo.
Mobility. You are no longer tied to one place and can use the Internet in a comfortable environment.
Within the Wi-Fi zone, several users can access the Internet from computers, laptops, phones, etc.
The radiation from Wi-Fi devices during data transmission is an order of magnitude (10 times) less than that of a cell phone.

Disadvantages of Wi-Fi

There are many devices operating in the 2.4 GHz band, such as devices that support Bluetooth, etc., and even microwaves, which worsens electromagnetic compatibility.
Equipment manufacturers specify the speed on L1 (OSI), which creates the illusion that the equipment manufacturer is overestimating the speed, but in fact Wi-Fi has a very high overhead. It turns out that the data transfer speed on L2 (OSI) in a Wi-Fi network is always lower than the declared speed on L1 (OSI). The actual speed depends on the share of service traffic, which depends on the presence of physical barriers between devices (furniture, walls), the presence of interference from other wireless devices or electronic equipment, the location of devices relative to each other, etc.
The frequency range and operating restrictions are not the same in different countries. Many European countries allow two additional channels that are prohibited in USA; In Japan there is another channel at the top of the range, and other countries, e.g. Spain , prohibit the use of low-frequency channels. Moreover, some countries, e.g. Russia, Belarus and Italy , require registration of all Wi-Fi networks operating outdoors, or require registration of the Wi-Fi operator.
As mentioned above in Russia, wireless access points, as well as Wi-Fi adapters with EIRP exceeding 100 mW (20 dBm) are subject to mandatory registration.
WEP encryption standard can be relatively easily hacked even with the correct configuration (due to the weak strength of the algorithm). New devices support more advanced data encryption protocol WPA and WPA2 . Adoption of the standard IEEE 802.11i (WPA2) in June 2004 made available a more secure scheme that is available in new equipment. Both schemes require more robust password than those typically assigned by users. Many organizations use additional encryption (for example VPN ) to protect against intrusion. At the moment, the main method of cracking WPA2 is password guessing, so it is recommended to use complex alphanumeric passwords in order to make the password guessing task as difficult as possible.
In mode point-to-point (Ad-hoc)the standard only requires the implementation of speeds of 11 Mbit/s (802.11b). WPA(2) encryption is not available, only the easily crackable WEP.

2) Bluetooth or bluetooth (/bluːtuːθ/ , translated as blue tooth, named after Harald I Bluetooth) wireless production specificationpersonal networks (English) Wireless personal area network, WPAN ). Bluetooth ensures the exchange of information between devices such as personal computers (desktops, pockets, laptops), mobile phones, printers, digital cameras, mice, keyboards, joysticks, headphones, headsets on a reliable, free, universally available radio frequency for short-range communication.

Bluetooth allows these devices to communicate when they are within a radius of up to 100 meters from each other (range varies greatly depending on obstacles and interference), even in different rooms.

History of creation and development

A telecommunications equipment manufacturer has begun work on creating Bluetooth. Ericsson in 1994 as a wireless alternative to cables RS-232 . Initially, this technology was tailored to the needs of the FLYWAY system for a functional interface between travelers and the system.

The Bluetooth specification was developed by the groupBluetooth Special Interest Group(Bluetooth SIG) , which was founded in 1998 . It included companies Ericsson, IBM, Intel, Toshiba and Nokia . Subsequently, the Bluetooth SIG and the IEEE reached an agreement whereby the Bluetooth specification became part of the IEEE 802.15.1 standard (published date June 14, 2002).

Class	Maximum power mW	Maximum power dBm	Radius of action, m

AIRcable has released the Host XR Bluetooth adapter with a range of about 30 km.

Specifications

Bluetooth 1.0

Device versions 1.0 (1998) and 1.0B had poor compatibility between products from different manufacturers. In 1.0 and 1.0B, it was mandatory to transmit the device address (BD_ADDR) at the handshake stage, which made it impossible to implement connection anonymity at the protocol level and was the main drawback of this specification.

Bluetooth 1.1

Bluetooth 1.1 corrected many bugs found in 1.0B, added support for unencrypted channels, indication of the received signal strength level ( RSSI).

Bluetooth 1.2

Version 1.2 added adaptive frequency hopping (AFH) technology, which improves immunity to electromagnetic interference (interference) by using staggered frequencies in the tuning sequence. The transmission speed has also increased and technology has been added eSCO , which improved the quality of voice transmission by repeating damaged packets. IN HCI added support for a three-wire interface UART.

Major improvements include the following:

Fast connection and discovery.
Adaptive frequency hopping with spread spectrum (AFH), which improves immunity to radio interference.
Higher data transfer rates than in 1.1, almost up to 721 kbit/s.
Enhanced Synchronous Coupling (eSCO), which improves the voice quality of an audio stream by allowing damaged packets to be retransmitted, and can optionally increase audio latency to better support parallel data transfers.
Support for a three-wire UART interface has been added to the Host Controller Interface (HCI).
Approved as standard IEEE Standard 802.15.1-2005.
Flow Control and Retransmission Modes have been introduced for L2CAP.

Bluetooth 2.0+EDR

Bluetooth version 2.0 was released on November 10, 2004. It is backward compatible with previous 1.x versions. The main innovation was support Enhanced Data Rate (EDR) to speed up data transfer. The nominal speed of EDR is about 3 Mbit/s, but in practice this allowed increasing the data transfer rate only to 2.1 Mbit/s. Additional performance is achieved using various radio technologies for data transmission.

The standard (base) data transfer rate uses GFSK -radio signal modulation at a transmission speed of 1 Mbit/s. EDR uses a combination of GFSK and PSK modulations with two options, π/4-DQPSK and 8DPSK. They have high data transfer rates over the air 2 and 3 Mbit/s respectively.

The Bluetooth SIG has published the specification as "Bluetooth 2.0 + EDR Technology", which implies that EDR is an optional feature. Besides EDR, there are other minor improvements to the 2.0 specification, and products may comply with "Bluetooth 2.0 Technology" without supporting higher data rates. At least one commercial device, the HTC TyTN Pocket PC, uses "Bluetooth 2.0 without EDR" in its technical specifications.

According to the 2.0+EDR specification, EDR provides the following benefits:

Increase the transfer speed by 3 times (2.1 Mbps) in some cases.
Reduced complexity of multiple simultaneous connections due to additional bandwidth.
Lower energy consumption due to load reduction.

Bluetooth 2.1

2007 Added technology for extended request for device characteristics (for additional filtering of the list when pairing), energy-saving technology Sniff Subrating , which allows you to increase the operating time of the device on a single battery charge by 3×10 times. In addition, the updated specification significantly simplifies and speeds up the establishment of communication between two devices, allows updating the encryption key without breaking the connection, and also makes these connections more secure thanks to the use of technology Near Field Communication.

Bluetooth 2.1+EDR

In August 2008, Bluetooth SIG introduced version 2.1+EDR. The new Bluetooth edition reduces energy consumption by 5 times, improves data security and makes it easier to recognize and connect Bluetooth devices by reducing the number of steps required.

Bluetooth 3.0+HS

3.0+HS was accepted by the Bluetooth SIG on April 21, 2009. It supports theoretical data transfer rates of up to 24 Mbps. Its main feature is the addition of AMP (Asymmetric Multiprocessing) (alternatively MAC/PHY), an addition to 802.11 as a high-speed message. Two technologies were provided for AMP: 802.11 and UWB, but UWB not in the specification.

Modules supporting the new specification combine two radio systems: the first provides data transmission at 3 Mbit/s (standard for Bluetooth 2.0) and has low power consumption; the second is compatible with the 802.11 standard and provides the ability to transfer data at speeds of up to 24 Mbit/s (comparable to network speeds WiFi ). The choice of radio system for data transmission depends on the size of the transmitted file. Small files are transmitted over a slow channel, and large ones over a high-speed channel. Bluetooth 3.0 uses the more generic 802.11 standard (without a suffix), meaning it is not compatible with Wi-Fi specifications such as 802.11b/g or 802.11n.

Bluetooth 4.0

See also: Bluetooth Low Energy

The Bluetooth SIG approved the Bluetooth 4.0 specification on June 30, 2010. Bluetooth 4.0 includes Classic Bluetooth, High Speed Bluetooth, and Bluetooth Low Energy protocols. High Speed Bluetooth is based on Wi-Fi, while Classic Bluetooth consists of protocols from previous Bluetooth specifications.

The Bluetooth Low Energy protocol is intended primarily for miniature electronic sensors (used in sports shoes, exercise equipment, miniature sensors placed on the body of patients, etc.). Low power consumption is achieved through the use of a special operating algorithm. The transmitter is turned on only while sending data, which makes it possible to operate on a single battery CR2032 for several years. The standard provides a data transfer rate of 1 Mbit/s with a data packet size of 8 x 27 bytes. In the new version, two Bluetooth devices will be able to establish a connection in less than 5 milliseconds and maintain it at a distance of up to 100 m. Advanced error correction is used for this, and the necessary level of security is provided by 128-bit AES encryption.

Sensors for temperature, pressure, humidity, speed of movement, etc. based on this standard can transmit information to various control devices: mobile phones, PDAs, PCs, etc.

The first chip supporting Bluetooth 3.0 and Bluetooth 4.0 was released by the company ST-Ericsson at the end of 2009.

Bluetooth 4.0 supported in MacBook Air and Mac mini (since July 2011), iMac (November 2012), iPhone 4S (October 2011) and iPhone 5 (September 2012), iPad 3 (March 2012) and iPad mini (since November 2012), LG Optimus 4X HD smartphones (February 2012), Google Nexus 4, HTC One X, S, V and Samsung Galaxy S III (May 2012), Explay Infinity (August 2012), HTC One X+ (2012), HTC Desire C, HTC Desire V, Google Nexus 7 (2012), Sony VAIO SVE1511N1RSI, Nokia Lumia 920 (September 18, 2012).

Bluetooth protocol stack

Bluetooth has a layered architecture consisting of a core protocol, cable replacement protocols, telephony control protocols, and derived protocols. Mandatory protocols for everyone Bluetooth stacks are: LMP, L2CAP and SDP. Additionally, devices communicating with Bluetooth typically use the HCI and RFCOMM protocols.

Link Management Protocol is used to establish and manage a radio connection between two devices. Implemented by a Bluetooth controller.

Host/controller interface defines the communication between the stack host (i.e. computer or mobile device) with a Bluetooth controller.

AVRCP

A/V Remote Control Profile is commonly used in car navigation systems to control the audio stream via Bluetooth.

L2CAP

Logical Link Control and Adaptation Protocol is used to multiplex local connections between two devices using different higher-level protocols. Allows you to fragment and rebuild packages.

Service Discovery Protocol allows you to discover services provided by other devices and determine their parameters.

RFCOMM

Radio Frequency Communications cable replacement protocol, creates a virtual serial data stream and emulates control signals RS-232.

BNEP

Bluetooth Network Encapsulation Protocol is used to transfer data from other protocol stacks over the L2CAP channel. Used for transmission IP packets in your Personal Area Networking profile.

AVCTP

Audio/Video Control Transport Protocol is used in the Audio/Video Remote Control profile to transmit commands over the L2CAP channel.

AVDTP

Audio/Video Distribution Transport Protocol is used in the Advanced Audio Distribution profile to transmit stereo audio over the L2CAP channel.

Telephony Control Protocol Binary protocol that defines call control signals for establishing voice and data connections between Bluetooth devices. Only used in the Cordless Telephony profile.

Borrowed protocols include: Point-to-Point Protocol ( PPP), TCP/IP, UDP, Object Exchange Protocol (OBEX ), Wireless Application Environment (WAE), Wireless Application Protocol (WAP).

3) WiMAX (W orldwide Interoperability for Microwave Access) telecommunicationstechnology developed to provide universalwireless communicationover long distances for a wide range of devices (from workstations and laptop computers before mobile phones). Based on standard IEEE 802.16 , which is also called Wireless MAN (WiMAX should be considered a slang name, since it is not a technology, but the name of the forum where Wireless MAN was agreed upon).

The name "WiMAX" was created WiMAX Forum an organization that was founded in June 2001 in order to promote and develop WiMAX technology. The forum describes WiMAX as “a standard-based technology that provides high-speed wireless network access as an alternative to leased lines and DSL " Maximum speed up to 1 Gbps per cell.

WiMAX is suitable for solving the following problems:

Access Point Connections WiFi with each other and other segments of the Internet.
Providing wireless broadband as an alternativededicated lines and DSL.
Providing high-speed data transmission and telecommunications services.
Creating access points , not tied to geographic location.
Creation of remote monitoring systems (monitoring systems), as it takes place in the system SCADA.

WiMAX allows access to Internet at high speeds, with much greater coverage than WiFi -networks. This allows the technology to be used as “trunk channels”, the continuation of which are traditional DSL and leased lines, as well as local networks . As a result, this approach allows the creation of scalable high-speed networks within cities.

Principle of operation

Basic Concepts

As mentioned above, WiMAX is used both to solve the problem " last mile ", and for providing network access to office and district networks.

Line-of-sight connections are established between base stations using the frequency range from 10 to 66 GHz, data exchange speeds can reach 140 Mbit/s. In this case, at least one base station is connected to the network provider using classic wired connections. However, the greater the number of BSs connected to the provider’s networks, the higher the data transfer speed and reliability of the network as a whole.

The network structure of the IEEE 802.16 family of standards is similar to traditional ones GSM networks (base stations operate at distances of up to tens of kilometers; for their installation it is not necessary to build towers; installation on the roofs of houses is allowed, subject to the conditions of direct visibility between the stations).

Operating modes

MAC/link layer

In Wi-Fi networks, all user stations that want to transmit information through an access point (AP) compete for the latter’s “attention”. This approach can cause a situation in which communications for more distant stations are constantly interrupted in favor of closer stations. This state of affairs makes it difficult to use services such as Voice over IP (VoIP), which are very dependent on an uninterrupted connection.

As for 802.16 networks, they MAC uses a scheduling algorithm. Any user station just needs to connect to the access point, a dedicated slot will be created for it on the access point, inaccessible to other users.

Architecture

The WiMAX Forum has developed an architecture that defines many aspects of the operation of WiMAX networks: interactions with other networks, distribution of network addresses, authentication and much more. The illustration above gives some idea of the architecture of WiMAX networks.

WiMAX Forum WiMAX Architecture

SS/MS: (the Subscriber Station/Mobile Station)
ASN: (the Access Service Network)
BS: (Base station), base station, part of ASN
ASN-GW: (the ASN Gateway), gateway, part of the ASN
CSN: (the Connectivity Service Network)
HA: (Home Agent, part of CSN)
NAP:(a Network Access Provider)
NSP: (a Network Service Provider)

ASN (Access Service Network) access network.

ASN Gateway is designed to aggregate traffic and signaling messages from base stations and forward them to the CSN network.

BS (Base Station) base station. The main task is to establish, maintain and disconnect radio connections. In addition, it performs signaling processing, as well as resource distribution among subscribers.

CSN (Connectivity Service Network) service provision network.

HA (Home Agent) network element responsible for roaming capabilities. In addition, it ensures data exchange between networks of different operators.

It should be noted that the architecture of WiMax networks is not tied to any specific configuration and is highly flexible and scalable.

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