Wireless standard 802.11 b. Wi-Fi, Standards

The IEEE (Institute of Electrical and Electronic Engineers) is developing WiFi 802.11 standards.

IEEE 802.11 is the base standard for Wi-Fi networks, which defines a set of protocols for the lowest data transfer rates (transfer).

IEEE 802.11b- describes b O higher transmission speeds and introduces more technological restrictions. This standard was widely promoted by WECA ( Wireless Ethernet Compatibility Alliance ) and was originally called WiFi .
Frequency channels in the 2.4GHz spectrum are used ().
Ratified in 1999.
RF technology used: DSSS.
Coding: Barker 11 and CCK.
Modulations: DBPSK and DQPSK,
Maximum data transfer rates (transfer) in the channel: 1, 2, 5.5, 11 Mbps,

IEEE 802.11a- describes significantly higher transfer rates than 802.11b.
Frequency channels in the 5GHz frequency spectrum are used. ProtocolNot compatible with 802.11 b.
Ratified in 1999.
RF technology used: OFDM.
Coding: Conversion Coding.
Modulations: BPSK, QPSK, 16-QAM, 64-QAM.
Maximum data transfer rates in the channel: 6, 9, 12, 18, 24, 36, 48, 54 Mbps.

IEEE 802.11g - describes data transfer rates equivalent to 802.11a.
Frequency channels in the 2.4GHz spectrum are used. The protocol is compatible with 802.11b.
Ratified in 2003.
RF technologies used: DSSS and OFDM.
Coding: Barker 11 and CCK.
Modulations: DBPSK and DQPSK,
Maximum data transfer rates (transfer) in the channel:
- 1, 2, 5.5, 11 Mbps on DSSS and
- 6, 9, 12, 18, 24, 36, 48, 54 Mbps on OFDM.

IEEE 802.11n- the most advanced commercial WiFi standard, currently officially approved for import and use in the Russian Federation (802.11ac is still being developed by the regulator). 802.11n uses frequency channels in the 2.4GHz and 5GHz WiFi frequency spectrums. Compatible with 11b/11 a/11g . Although it is recommended to build networks targeting only 802.11n, because... requires configuration of special protective modes if backward compatibility with legacy standards is required. This leads to a large increase in signal information anda significant reduction in the available useful performance of the air interface. Actually, even one WiFi 802.11g or 802.11b client will require special configuration of the entire network and its immediate significant degradation in terms of aggregated performance.
The WiFi 802.11n standard itself was released on September 11, 2009.
WiFi frequency channels with a width of 20MHz and 40MHz (2x20MHz) are supported.
RF technology used: OFDM.
OFDM MIMO (Multiple Input Multiple Output) technology is used up to the 4x4 level (4xTransmitter and 4xReceiver). In this case, a minimum of 2xTransmitter per Access Point and 1xTransmitter per user device.
Examples of possible MCS (Modulation & Coding Scheme) for 802.11n, as well as the maximum theoretical transfer rates in the radio channel are presented in the following table:

Here SGI is the guard intervals between frames.
Spatial Streams is the number of spatial streams.
Type is the modulation type.
Data Rate is the maximum theoretical data transfer rate in a radio channel in Mbit/sec.

It is important to emphasize that the indicated speeds correspond to the concept of channel rate and are the maximum value using a given set of technologies within the framework of the described standard (in fact, these values, as you probably noticed, are written by manufacturers on the boxes of home WiFi devices in stores). But in real life, these values ​​are not achievable due to the specifics of the WiFi 802.11 standard technology itself. For example, “political correctness” is strongly influenced here in terms of ensuring CSMA/CA ( WiFi devices constantly listen to the air and cannot transmit if the transmission medium is busy), the need to acknowledge each unicast frame, the half-duplex nature of all WiFi standards and only 802.11ac/Wave-2 can begin to bypass this, etc. Therefore, the practical effectiveness of outdated 802.11 standards b/g/a never exceeds 50% under ideal conditions (for example, for 802.11g the maximum speed per subscriber is usually no higher than 22Mb/s), and for 802.11n the efficiency can be up to 60%. If the network operates in protected mode, which often happens due to the mixed presence of different WiFi chips on different devices on the network, then even the indicated relative efficiency can drop by 2-3 times. This applies, for example, to a mix of Wi-Fi devices with 802.11b, 802.11g chips in a network with WiFi 802.11g access points, or WiFi 802.11g/802.11b devices in a network with WiFi 802.11n access points, etc. Read more about .

In addition to the basic WiFi standards 802.11a, b, g, n, additional standards exist and are used to implement various service functions:

. 802.11d. To adapt various WiFi standard devices to specific country conditions. Within the regulatory framework of each state, ranges often vary and may even differ depending on geographic location. The WiFi IEEE 802.11d standard allows you to adjust frequency bands in devices from different manufacturers using special options introduced into the media access control protocols.

. 802.11e. Describes QoS quality classes for the transmission of various media files and, in general, various media content. Adaptation of the MAC layer for 802.11e determines the quality of, for example, simultaneous transmission of audio and video.

. 802.11f. Aimed at unifying the parameters of Wi-Fi standard Access Points from various manufacturers. The standard allows the user to work with different networks when moving between coverage areas of individual networks.

. 802.11h. Used to prevent problems with weather and military radars by dynamically reducing the emitted power of Wi-Fi equipment or dynamically switching to another frequency channel when a trigger signal is detected (in most European countries, ground stations tracking weather and communications satellites, as well as military radars operate in ranges close to 5 MHz). This standard is necessary requirement ETSI requirements for equipment approved for operation in the countries of the European Union.

. 802.11i. The first iterations of the 802.11 WiFi standards used the WEP algorithm to secure Wi-Fi networks. It was assumed that this method could ensure confidentiality and protection of transmitted data of authorized users without wired network from eavesdropping. Now this protection can be hacked in just a few minutes. Therefore, the 802.11i standard developed new methods for protecting Wi-Fi networks, implemented at both the physical and software levels. Currently, to organize a security system in Wi-Fi 802.11 networks, it is recommended to use Wi-Fi Protected Access (WPA) algorithms. They also provide compatibility between wireless devices of different standards and modifications. WPA protocols use an advanced RC4 encryption scheme and a mandatory authentication method using EAP. Sustainability and safety modern networks Wi-Fi is defined by privacy verification and data encryption protocols (RSNA, TKIP, CCMP, AES). The most recommended approach is to use WPA2 with AES encryption (and don't forget about 802.1x using tunneling mechanisms, such as EAP-TLS, TTLS, etc.). .

. 802.11k. This standard is actually aimed at implementing load balancing in the radio subsystem of a Wi-Fi network. Usually wireless local network The subscriber device usually connects to the access point that provides the strongest signal. This often leads to network congestion at one point, when many users connect to one Access Point at once. To control such situations, the 802.11k standard proposes a mechanism that limits the number of subscribers connected to one Access Point and makes it possible to create conditions under which new users will join another AP even despite a weaker signal from it. In this case, the aggregated network throughput increases due to more efficient use of resources.

. 802.11m. Amendments and corrections for the entire group of 802.11 standards are combined and summarized in a separate document under the general name 802.11m. The first release of 802.11m was in 2007, then in 2011, etc.

. 802.11p. Determines the interaction of Wi-Fi equipment moving at speeds of up to 200 km/h past stationary WiFi Access Points located at a distance of up to 1 km. Part of the Wireless Access in Vehicular Environment (WAVE) standard. WAVE standards define an architecture and a complementary set of utility functions and interfaces that provide a secure radio communications mechanism between moving vehicles. These standards are developed for applications such as traffic management, traffic safety monitoring, automated payment collection, vehicle navigation and routing, etc.

. 802.11s. A standard for implementing mesh networks (), where any device can serve as both a router and an access point. If the nearest access point is overloaded, data is redirected to the nearest unloaded node. In this case, a data packet is transferred (packet transfer) from one node to another until it reaches its final destination. This standard introduces new protocols at the MAC and PHY levels that support broadcast and multicast transmission (transfer), as well as unicast delivery over a self-configuring point system Wi-Fi access. For this purpose, the standard introduced a four-address frame format. Implementation examples WiFi networks Mesh: , .

. 802.11t. The standard was created to institutionalize the process of testing solutions of the IEEE 802.11 standard. Testing methods, methods of measurement and processing of results (treatment), requirements for testing equipment are described.

. 802.11u. Defines procedures for interaction of Wi-Fi standard networks with external networks. The standard must define access protocols, priority protocols and prohibition protocols for working with external networks. At the moment, a large movement has formed around this standard, both in terms of developing solutions - Hotspot 2.0, and in terms of organizing inter-network roaming - a group of interested operators has been created and is growing, who jointly resolve roaming issues for their Wi-Fi networks in dialogue (WBA Alliance ). Read more about Hotspot 2.0 in our articles: , .

. 802.11v. The standard should include amendments aimed at improving the network management systems of the IEEE 802.11 standard. Modernization at the MAC and PHY levels should allow the configuration of client devices connected to the network to be centralized and streamlined.

. 802.11y. Additional communication standard for the frequency range 3.65-3.70 GHz. Designed for latest generation devices operating with external antennas at speeds up to 54 Mbit/s at a distance of up to 5 km in open space. The standard is not fully completed.

802.11w. Defines methods and procedures for improving the protection and security of the media access control (MAC) layer. The standard protocols structure a system for monitoring data integrity, the authenticity of their source, the prohibition of unauthorized reproduction and copying, data confidentiality and other protection measures. The standard introduces management frame protection (MFP: Management Frame Protection), and additional security measures help neutralize external attacks, such as DoS. A little more on MFP here: . In addition, these measures will ensure security for the most sensitive network information that will be transmitted over networks that support IEEE 802.11r, k, y.

802.11ac. A new WiFi standard that operates only in the 5GHz frequency band and provides significantly faster O higher speeds both for an individual WiFi client and for a WiFi Access Point. See our article for more details.

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For almost two decades since the first standards wireless communication 802.11, five universal ones appeared: 802.11a, 802.11b, 802.11g, 802.11n and 802.11ac. With each new standard, Wi-Fi network speeds have only increased.

It turned out that this is not the limit: they are being replaced by new Wi-Fi standard– 802.11 ax (or 11AX), which is aimed at improving Wi-Fi performance in environments with large amounts of data traffic and frequent network congestion.

Wi-Fi 802.11 ax – increased speed and capacity

If you've ever tried to connect to Wi-Fi at a concert or at an airport, of course you know how many limitations networks have in such a dense environment. An excess of users trying to receive a wireless signal puts too much strain on the network, which reduces its performance and signal stability. Standard 11AX solves this problem by offering better system routing data where it is needed.

Main purpose of previous standards wireless networks was achieving maximum theoretical speed. And only the latest standard - 802.11 ac - expanded the possibilities for connecting multiple antennas.

Wi-Fi 11AX still divides the frequency band into multiple channels using OFDMA (Orthogonal Frequency Division Multiple Access) technology. But, at the same time, 11AX can significantly increase the speed of a wireless network and better manage its throughput, especially in high traffic volumes and overlapping networks.

What is the speed on Wi-Fi 11AX

The maximum speed of a single 802.11ac stream is about 866 Mbps, while a single 802.11ax stream reaches 1.2 Gb/s. This means the ability to stream Ultra-HD 4K video with zero latency, download entire software packages in the blink of an eye, and integrate with your entire family of smart devices.

The speeds you can get depend, of course, on the network and the equipment it uses. Big professional network, which already has a strong signal, will obviously have significantly higher speed than networks in small companies. Either way, it is possible to achieve a fourfold increase in the current signal, which means a significant increase in the overall network capacity.

Lower speed limit? In addition to improving performance and range, 11AX is designed to increase the capacity of the 2.4 GHz and 5 GHz frequency bands in a variety of environments - from home to school, business, airport, stadium and more. It doesn't matter where you use your Wi-Fi network. -Fi, you can achieve 4 times the current speed.

Efficiency of Wi-Fi 11AX standard

Speed ​​is not the only important factor. 11AX also aims to implement mechanisms that provide a consistent and reliable flow of data to a larger number of users. This means improved performance and continued connectivity even in the face of high volumes of network traffic.

The 11AX standard operates on both 2.4 and 5 GHz frequencies, preserving existing channel capacities while increasing network capacity and expanding the way data can be transferred to multiple devices.

Standard 11AX also supports Orthogonal Frequency Division Multiple Access (OFDMA), a technology designed to improve throughput mobile networks LTE.

In its current application, every time a router transmits data to a device, it uses the entire bandwidth in the channel, regardless of the type of data or amount of information that is actively downloaded. With OFDMA, these channels can be separated, increasing the amount of data that can be sent and received simultaneously.

Besides, new 802.11ax standard allows you to schedule a “wake-up” time when communication is allowed (which reduces load). The 11AX not only supports 1024QAM encoding to carry more units of information per symbol, but also long OFDM symbols for higher channel capacity and less interference.

Features and Benefits of Wi-Fi 11AX

Most Wi-Fi users understand that connecting multiple devices reduces network throughput, resulting in slowdowns, unnecessary caching, and connection dropouts.

The new standard, also called High-Efficiency Wireless (HEW), provides another level of Wi-Fi control.

The standard includes the following main functions:

• Backwards compatible with previous Wi-Fi standards (802.11 a/b/g/n/ac)
• Ability to operate on the 5 GHz and 2.4 GHz bands simultaneously (and not one or the other, as in previous standards).
• Channel width 2/5/10 MHz for bands wider than 20 MHz.
• Increased throughput and performance:
  • 1.5 times faster than 802.11ac
  • 3.8 times faster than 2.4GHz 802.11n
• High capacity in high-density environments (such as stadiums)
• Up to 8 times faster than non-MU-MIMO devices using MU-MIMO upper and lower level (DL/UL) links
• 20% more airtime from the router, meaning more data can be transferred
• Improved power management for longer battery life
• Color BSS - in other words, each network will receive its own color, making them easy to distinguish

When is the 11AX standard launching?

Due to the fact that Wi-Fi 11AX improves average data transfer speeds On a per-user basis, this standard is best suited for high-density environments such as hotels, apartment buildings, and campuses.

When many users' devices are connected to the same network, they have to compete for available resources and transfer data sequentially, one at a time. With 11AX, multiple devices can simultaneously transmit data using the same frequency and the same network.

That is Wi-Fi in 11AX standard– this is not only an increase in network speed. This standard improves performance and eliminates problems caused by Wi-Fi network congestion and congestion.

The opportunity to create a local network without the use of cables looks very tempting and the advantages of this approach are obvious. Let's take, for example, a standard apartment. When creating a local network, the first question that arises before the computer owner is how to hide all the cables so that they do not get tangled underfoot? To do this, you have to either purchase special boxes that are mounted on the ceiling or walls, or use other methods, including the most obvious ones, for example, hiding the cables under the carpet.

However, few people want to spend time, money and effort on laying the cable so that it is not conspicuous. In addition, there is always a risk of bending a certain segment of the cable, as a result of which the network for an individual computer or all computers will be inoperable.

The solution to this problem is wireless networks (WLANs). The main technology used to create wireless networks based on radio waves is Wi-Fi technology. This technology is rapidly gaining popularity, and many home local networks have already been created on its basis. There are currently three main Wi-Fi standards, each with specific characteristics: 802.11b, 802.11a, and 802.11g. We are talking about the most popular standards, since in reality there are many more of them, and some of them are still undergoing the standardization process. For example, 802.11n equipment is already on sale, but the standard is still developing.

The structure of a conventional wireless network is practically no different from the structure of a wired network. All computers on the network are equipped with a wireless adapter, which has an antenna and connects to the PCI connector of the computer (internal adapter) or USB connector (external adapter). For laptops, you can use both external USB adapters and adapters for the PCMCIA connector, in addition, many laptops are initially equipped with a Wi-Fi adapter. The interaction of computers and portable systems equipped with Wi-Fi adapters is ensured by an access point, which can be considered an analogue of a switch in a wired network.

There are currently three main wireless network standards:

• 801.11b;

Let's take a closer look at these standards.

802.11 standardb was the first certified Wi-Fi standard. All 801.11b compliant devices must have the appropriate Wi-Fi label. The main characteristics of 801.11b are as follows:

• data transfer speed up to 11 Mbit/s;
• range up to 50 m;
• frequency 2.4 GHz (same as the frequency of some cordless phones and microwave ovens);
• 802.11b devices have the least compared to other Wi-Fi devices, price.

The main advantage of 801.11b is its universal availability and low price. There are also significant disadvantages, such as the low data transfer speed (almost 9 times less than the speed in the 100BASE-TX network) and the use of radio frequency, which coincides with the radio frequency of some household devices.

802.11 standarda was designed to solve the problem of low throughput in 801.11b networks. 801.11a specifications are shown below:

• range up to 30 m;
• frequency 5 GHz;
• incompatibility with 802.11b;
• higher price of devices compared to 802.11b.

The advantages are obvious - data transfer speeds up to 54 Mbit/s and an operating frequency not used in household appliances, however, this comes at the expense of a lower range and lack of compatibility with the popular 802.11b standard.

Third standard, 802.11g, gradually gained more popularity due to its data transfer speed and compatibility with 802.11b. The characteristics of this standard are as follows:

• data transfer speed up to 54 Mbit/s;
• range up to 50 m;
• frequency 2.4 GHz;
• Full compatibility with 802.11b;
• the price is almost equal to the price of 802.11b devices.

802.11g standard devices can be recommended for creating wireless home network. A data transfer speed of 54 Mbit/s and a range of up to 50 m from the access point will be sufficient for any apartment, however, for a larger room, the use of wireless communications of this standard may be unacceptable.

Let's also talk about the 802.11n standard, which will very soon supplant the other three standards.

• data transfer speeds up to 200 Mbit/s (and in theory, up to 480 Mbit/s);
• range of action up to 100 meters;
• frequency 2.4 or 5 GHz;
• compatible with 802.11b/g and 802.11a;
• the price is rapidly decreasing.

Of course, 802.11n is the coolest and most promising standard. The range is longer and the transmission speed is many times higher than that of the other three standards. However, do not rush to run to the store. 802.11n has a few disadvantages that you need to be aware of.

one of the best 802.11n routers.

Most importantly, to enjoy all the benefits of 802.11n, all devices on your wireless network must support this standard. If one of the devices runs on, say, 802.11g, the 802.11n router will be put into compatibility mode and its speed and range advantages will simply disappear. So if you want an 802.11n network, you need all the devices that will be on the wireless network to support this standard.

Moreover, it is desirable that the 802.11n devices be from the same company. Since the standard is still being developed, different companies implement its capabilities in their own way, and there are often incidents when wireless device from Asus the 802.11n standard does not want to work properly with Linksys, etc.

So before you implement 802.11n in your home, consider whether you have taken these factors into account. Well, of course, read what people write on forums where this topic is actively discussed.

If the apartment has several rooms with reinforced concrete walls, the transmission speed at a distance of 20-30 m will be lower than the maximum. The data transfer speed from the access point to the device will decrease in proportion to the distance to this device, since the speed will be reduced automatically to maintain a stable signal.

It is advisable not to place the access point near household or office devices such as microwave ovens, cordless phones, fax machines, printers, etc. .

Having decided to implement a wireless network, you should select the appropriate equipment, which includes, as mentioned earlier, two key components - an access point and wireless adapters. This is discussed in the article “ “.

If you're looking for the fastest WiFi, you need 802.11ac, it's as simple as that. Essentially, 802.11ac is an accelerated version of 802.11n (the current WiFi standard used on your smartphone or laptop), offering link speeds ranging from 433 megabits per second (Mbps), up to several gigabits per second. To achieve speeds that are tens of times faster than 802.11n, 802.11ac operates exclusively in the 5GHz band, uses huge bandwidth (80-160MHz), works with 1-8 spatial streams (MIMO), and uses a peculiar technology called "beamforming" (beamforming). We'll talk more about what 802.11ac is and how it will eventually replace wired Gigabit Ethernet in your home and work networks.

How 802.11ac works.

A few years ago, 802.11n introduced some interesting technology that significantly increased speed compared to 802.11b and g. 802.11ac works almost the same as 802.11n. For example, while the 802.11n standard supported up to 4 spatial streams, and a channel width of up to 40 MHz, 802.11ac can use 8 channels, and a width of up to 80 MHz, and combining them can generally produce 160 MHz. Even if everything else remained the same (and it won't), this means that 802.11ac handles 8x160MHz spatial streams, compared to 4x40MHz. A huge difference that will allow you to squeeze huge amounts of information out of radio waves.

To improve throughput even further, 802.11ac also introduced 256-QAM modulation (compared to 64-QAM in 802.11n), which literally compresses 256 different signals of the same frequency, shifting and interweaving each one into a different phase. Theoretically, this increases the spectral efficiency of 802.11ac by 4 times compared to 802.11n. Spectral efficiency is a measure of how well a wireless protocol or multiplexing technique uses the bandwidth available to it. In the 5GHz band, where the channels are quite wide (20MHz+), spectral efficiency is not so important. In the cellular bands, however, channels are most often 5 MHz wide, making spectral efficiency extremely important.

802.11ac also introduces standardized beamforming (802.11n had it but was not standardized, making interoperability an issue). Beamforming essentially transmits radio signals in such a way that they are aimed at specific device. This can improve overall throughput and make it more consistent, as well as reduce power consumption. Beam shaping can be done by using a smart antenna that physically moves in search of the device, or by modulating the amplitude and phase of the signals so that they destructively interfere with each other, leaving a narrow, non-interfering beam. 802.11n uses the second method, which can be used by both routers and mobile devices. Finally, 802.11ac, like previous versions of 802.11, is fully backwards compatible with 802.11n and 802.11g, so you can buy an 802.11ac router today and it will work perfectly with your older WiFi devices.

802.11ac range

Theoretically, at 5 MHz and using beamforming, 802.11ac should have the same or better range as 802.11n (white beam). The 5 MHz band, due to its lower penetrating power, does not have the same range as 2.4 GHz (802.11b/g). But that's a trade-off we're forced to make: we simply don't have enough spectral bandwidth in the heavily used 2.4GHz band to allow 802.11ac's peak gigabit-level speeds. As long as your router is in the perfect location, or you have several of them, there is no need to worry. As always, the more important factor is the power transmission of your devices, and the quality of the antenna.

How fast is 802.11ac?

And finally, the question everyone wants to know: how fast is 802.11ac WiFi? As always, there are two answers: the speed theoretically achievable in the lab, and the practical speed limit you'll likely be content with in a real-world home environment surrounded by a bunch of signal-jamming obstacles.

The theoretical maximum speed of 802.11ac is 8 channels of 160MHz 256-QAM, each capable of 866.7Mbps, giving us 6.933Mbps, or a modest 7Gbps. Transfer speed of 900 megabytes per second is faster than transfer to a SATA 3 drive. In the real world, due to channel clogging, you most likely will not get more than 2-3 160 MHz channels, so the maximum speed will stop somewhere at 1.7-2.5 Gbit/s. Compared to 802.11n's theoretical maximum speed of 600Mbps.

Apple Airport Extreme at 802.11ac, disassembled by iFixit's most powerful router today (April 2015), includes D-Link AC3200 Ultra Wi-Fi Router (DIR-890L/R), Linksys Smart WiFi Router AC 1900 (WRT1900AC), and Trendnet AC1750 Dual-Band Wireless Router (TEW-812DRU), as reported by PCMag. With these routers, you can definitely expect impressive speeds from 802.11ac, but don't bite yours just yet. Gigabit Ethernet cable.

In Anandtech's 2013 test, they tested a WD MyNet AC1300 802.11ac router (up to three streams) paired with a number of 802.11ac devices that supported 1-2 streams. The fastest transfer speed was achieved by an Intel 7260 laptop with an 802.11ac wireless adapter, which used two streams to achieve 364Mbps over a distance of just 1.5m. At 6m and through the wall, the same laptop was the fastest, but the maximum speed was 140Mb/s. The fixed speed limit for the Intel 7260 was 867Mb/s (2 streams of 433Mb/s).

In a situation where you don't need maximum performance and the reliability of wired GigE, 802.11ac is truly compelling. Instead of cluttering your living room with an Ethernet cable running to your home theater from your PC under your TV, it makes more sense to use 802.11ac, which has enough bandwidth to wirelessly deliver high-definition content to your HTPC. For all but the most demanding cases, 802.11ac is very a worthy replacement Ethernet.

The future of 802.11ac

802.11ac will become even faster. As we mentioned earlier, the theoretical maximum speed of 802.11ac is a modest 7Gbps, and until we hit that in the real world, don't be surprised by the 2Gbps mark in the next few years. At 2Gbps, you get 256Mbps transfer speeds, and suddenly Ethernet will be used less and less until it disappears. To achieve such speeds, chipset and device manufacturers will have to figure out how to implement four or more channels for 802.11ac, given how software, and hardware.

We see Broadcom, Qualcomm, MediaTek, Marvell, and Intel already making strong moves to provide 4-8 channels for 802.11ac to integrate the latest routers, access points, and mobile devices. But until the 802.11ac specification is finalized, a second wave of chipsets and devices is unlikely to appear. Device and chipset manufacturers will need to do a lot of work to ensure that advanced technologies like beamforming meet the requirements of the standard and are fully compatible with other 802.11ac devices.

Hi all! Today we will talk again about routers, wireless networks, technologies...

I decided to prepare an article in which I would talk about what kind of strange letters b/g/n are these that can be found when setting up a Wi-Fi router, or when purchasing a device (Wi-Fi characteristics, for example 802.11 b/g). And what is the difference between these standards.

Now we’ll try to figure out what these settings are and how to change them in the router settings and actually why change the operating mode of the wireless network.

Means b/g/n– this is the operating mode of the wireless network (Mode).

The following groups of standards exist:

IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n and IEEE 802.11ac complete the operation of network equipment (physical layer):
IEEE 802.11d. IEEE 802.11e. IEEE 802.11i. IEEE 802.11j. IEEE 802.11h and IEEE
802.11r - environmental parameters, radio channel frequencies, security features, methods of transmitting multimedia data, etc.;
IEEE 802.11f IEEE 802.11c - the principle of interaction between access points, the operation of radio bridges, etc.

IEEE 802.11

Standard IE EE 802.11 was the “first-born” among wireless network standards. Work on it began back in 1990. As expected, this was done by a working group from IEEE, whose goal was to create a single standard for radio equipment that operated at the 2.4 GHz frequency. The goal was to achieve speeds of 1 and 2 Mbit/s using the DSSS and FHSS methods, respectively.

Work on creating the standard ended after 7 years. The goal was achieved but at a speed. provided by the new standard turned out to be too small for modern needs. Therefore, a working group from IEEE began developing new, faster standards.
The developers of the 802.11 standard took into account the features of the cellular architecture of the system. Why cell phone? It’s very simple: just remember that waves propagate in different directions over a certain radius. It turns out that the zone looks like a honeycomb. Each such cell operates under the control of a base station, which acts as an access point. A cell is often called basic service area.

So that the basic service areas can communicate with each other, there is a special distribution system (Distribution System. DS). The disadvantage of the 802.11 distribution system is the impossibility of roaming.

Standard IEEE 802.11 provides for the operation of computers without an access point, as part of one cell. In this case, the functions of the access point are performed by the workstations themselves.

This standard was developed and focused on equipment operating in the frequency band 2400-2483.5 MHz. In this case, the cell radius reaches 300 m, without limiting the network topology.

IEEE 802.11a

IEEE 802.11a This is one of the promising wireless network standards, which is designed to operate in two radio bands - 2.4 and 5 GHz. The OFDM method used allows achieving a maximum data transfer rate of 54 Mbnt/s. In addition to this, the specifications provide for other speeds:

• mandatory 6. 12 n 24 Mbnt/s;

• optional - 9, 18.3G. 18 and 54 Mbnt/s.

This standard also has its advantages and disadvantages. The advantages include the following:

• use of parallel data transmission;

• high transmission speed;

802.11n devices can operate in one of two bands 2.4 or 5.0 GHz.

On physical level(PHY) improved signal processing and modulation have been implemented, and the ability to simultaneously transmit a signal through four antennas has been added.

The network layer (MAC) allows for more efficient use of available bandwidth. Together, these enhancements allow theoretical data transfer rates to be increased by up to 600 Mbit/s– an increase of more than ten times, compared to 54 Mbps of the 802.11a/g standard (these devices are currently considered obsolete).

In reality, the performance of a wireless LAN depends on numerous factors such as the transmission medium, radio wave frequency, device placement and configuration. When using 802.11n devices, it is critical to understand what improvements have been made to this standard, what they affect, and how they fit and coexist with legacy 802.11a/b/g wireless networks. It is important to understand exactly what additional features of the 802.11n standard are implemented and supported in new wireless devices.

One of the main points of the 802.11n standard is its support for the technology MIMO(Multiple Input Multiple Output, Multi-channel input/output).
Using MIMO technology, the ability to simultaneously receive/transmit several data streams through several antennas, instead of one, is realized.

Standard 802.11n defines various antenna configurations "MxN", starting with "1x1" to "4x4"(the most common configurations today are “3x3” or “2x3”). The first number (M) determines the number of transmitting antennas, and the second number (N) determines the number of receiving antennas. For example, an access point with two transmit and three receive antennas is "2x3" MIMO-device. I will describe this standard in more detail later.