802.11 wireless standards. All existing Wi-Fi network standards

One of the most important settings wired network, these are “Operation Mode”, “Wireless Network Mode”, “Mode”, etc. The name depends on the router, firmware, or control panel language. This item in the router settings allows you to set a specific Wi-Fi operating mode (802.11). Most often, this is a mixed b/g/n mode. Well, ac if you have a dual-band router.

To determine which mode is best to choose in the router settings, you must first understand what it is and what these settings affect. I think it would be useful to take a screenshot with these settings as an example TP-Link router. For the 2.4 and 5 GHz range.

On this moment There are 4 main modes: b/g/n/ac. The main difference is the maximum connection speed. Please note that the speed that I will write about below is the maximum possible speed (per channel). Which can be obtained in ideal conditions. In real conditions, the connection speed is much lower.

IEEE 802.11 is a set of standards on which all Wi-Fi networks operate. Essentially, this is Wi-Fi.

Let's take a closer look at each standard (essentially these are Wi-Fi versions):

• 802.11a– when I wrote about the four main modes, I did not consider it. This is one of the first standards operating in the 5 GHz band. Maximum speed 54 Mbit/s. Not the most popular standard. Well, he’s already old. Now in the 5 GHz range the ac standard is already “ruling”.
• 802.11b– operates in the 2.4 GHz band. Speed ​​up to 11 Mbit/s.
• 802.11g– we can say that this is a more modern and modified 802.11b standard. It also works in the 2.4 GHz band. But the speed is already up to 54 Mbit/s. Compatible with 802.11b. For example, if your device can operate in this mode, then it will connect without problems to networks that operate in mode b (older).
• 802.11n– the most popular standard today. Speeds up to 150 Mbps in the 2.4 GHz band and up to 600 Mbps in the 5 GHz band. 802.11a/b/g compatible.
• 802.11ac– a new standard that operates only in the 5 GHz band. Data transfer rates up to 6.77 Gbps (with 8 antennas and MU-MIMO mode). This mode only available on dual-band routers that can broadcast the network in the 2.4 GHz and 5 GHz bands.

Connection speed

As practice shows, most often the b/g/n/ac settings are changed in order to increase the speed of the Internet connection. Now I will try to explain how it works.

Let's take the most popular standard 802.11n in the 2.4 GHz band, when the maximum speed is 150 Mbit/s. This is the number most often indicated on the box with the router. It may also say 300 Mbit/s, or 450 Mbit/s. This depends on the number of antennas on the router. If there is one antenna, then the router operates in one stream and speeds up to 150 Mbit/s. If there are two antennas, then two streams and the speed is multiplied by two - we get up to 300 Mbit/s, etc.

These are all just numbers. In real conditions, the Wi-Fi speed when connected in 802.11n mode will be 70-80 Mbit/s. Speed ​​depends on a huge number of different factors: interference, signal strength, performance and load on the router, settings, etc.

Since they have many versions of the web interface, let's look at a few of them. If in your case the web interface is light like in the screenshot below, then open the “Wi-Fi” section. There will be a point " Wireless mode"with four options: 802.11 B/G/N mixed, and separately N/B/G.

Or even like this:

Setting "802.11 Mode".

Radio frequency range on the Netis router

Open the settings page in your browser at http://netis.cc. Then go to the "Wireless" section.

There will be a menu "Radio frequency range". It allows you to change the Wi-Fi network standard. The default is "802.11 b+g+n".

Nothing complicated. Just don't forget to save the settings.

Setting up Wi-Fi network mode on the Tenda router

The settings are located in the "Wireless Mode" - "Basic WIFI Settings" section.

Item "Network mode".

You can install both mixed mode (11b/g/n) and separately. For example, only 11n.

If you have a different router or settings

Provide specific instructions for all devices and versions software It's simply impossible. Therefore, if you need to change the wireless network standard, and you did not find your device above in the article, then look at the settings in the section called “Wireless network”, “WiFi”, “Wireless”.

If you don’t find it, write the model of your router in the comments. And it is advisable to attach a screenshot from the control panel. I'll tell you where to look for these settings.

Indeed, despite the fact that Wi-Fi wireless networks have gained widespread recognition and distribution, they still have three main disadvantages: low (compared to wired Ethernet) real data transfer speed, difficulties with uniform coverage (and the presence of so-called dead zones - dead spots) and problems of data security and unauthorized access. Now let's look at the main advantages of devices created according to the 802.11n specification. It's more noticeable high speed data transmission, improved security thanks to the introduction of the new WPA2 encryption algorithm, as well as a significant expansion of coverage area and greater noise immunity. But, of course, we have long been accustomed to the fact that advertising and marketing figures that promise multiple improvements in a variety of indicators, of course, have something in common with real characteristics, but do not always coincide with them even in order of magnitude. And in order to correctly assess new opportunities and their limitations, it always makes sense to imagine how, in fact, these new opportunities are achieved.

A little theory. The theoretical connection speed for 802.11n devices is 300 Mbit/s, and for devices of the previous and most common 802.11g - 54 Mbit/s. Both figures correspond to ideal conditions that do not exist in nature. But still, how can an increase in speed of more than 5 times be achieved? If you ask this question to an inquisitive child, who, fortunately, does not yet have to demonstrate deep knowledge of radio physics, he will definitely speak in the spirit that new devices have more antennas sticking out, which means they work faster. And in general, this is approximately how it is, an increase in speed and stable coverage area is achieved largely thanks to multipath propagation technology (MIMO - Multiple Input Multiple Output), in which data is divided between several transmitters operating at the same frequency.

The developers did not abandon another simple and clear way to increase speed - using two frequency channels instead of one. If 802.11g uses one frequency channel with a width of 20 MHz, then 802.11n uses technology that links two channels located next to each other into one with a width of 40 MHz (information about using two channels instead of one will be very useful to us in practice when setting up devices for maximum performance).

One of the reasons why the actually observed speed in network applications is always less than that declared by the manufacturer is that in addition to the actual transmitted data, devices also exchange service information through the same communication channel. So the speed network connection at the application level is always less than at the physical level. Well, for obvious reasons, it is customary to indicate on the box a value that is larger in absolute value without any additional clarification. Accordingly, another opportunity to increase the real data transfer speed is to optimize the “overhead”, i.e. the volume of transferred service data, primarily by combining several data frames into one at the physical level.

Of course, these are just some of the major innovations in the 802.11n standard. But, strictly speaking, a complete and final specification for 802.11n devices does not exist until today. And this is another, much less joyful reason for the close attention to the new standard and the large number of conversations about it. The adoption of its final IEEE 802.11n specification has been delayed for several years and currently scheduled for the second half of 2008, but there is no guarantee that approval of the document will not be delayed again. At the same time, many manufacturers tried to be among the first to introduce devices to the market based on preliminary versions of the standard, which at some point led to the emergence of crude and poorly compatible devices, which, moreover, often lost in speed compared to non-standardized ones. solutions from other manufacturers (see “Draft-N: don’t rush with speed”, “PC World”, ). Since then, a preliminary version of the 802.11n Draft 2.0 standard has been approved, the Wi-Fi Alliance took over the certification without waiting for the official approval of IEEE 802.11n, and the developers have had enough time to eliminate the shortcomings characteristic of the first device models. The list of certified devices is available on the website www.wifialliance.org, and it was this list that we relied on when planning to test the first 802.11n Draft 2.0 devices.

Practice. As usual, of the eight certified devices whose manufacturers are represented in Russia, only three sets of equipment, consisting of an access point and the corresponding adapter, were actually available - DIR-655 and DWA-645 from D-Link, WNR854T and WN511T from Netgear, and also BR-6504n and EW-7718Un from Edimax. By the way, each of the routers in question turned out to be equipped with four Gigabit Ethernet ports, and wired connection, thus, obviously did not limit the connection speed we measured in any way (for details of measurements, see the sidebar “How we tested”). It is hardly worth going into detail appearance and the configuration of each device (all such information is presented on the corresponding manufacturers’ websites). Of course, appearance is far from the main quality of a router, but it’s not that insignificant either, because for the best signal distribution, it is logical to place this device in a high and visible place. The Netgear model will probably attract the most attention here - it has no external antennas. From observations while setting up routers, it’s probably worth mentioning quite useful function automatic selection of the most free frequency channel, implemented in D-Link DIR-655. Note that before installation it may make sense to download from the manufacturer’s website latest version drivers - for example, initially the Netgear adapter fundamentally did not want to establish connections using the 802.11n standard with routers from other manufacturers, but updating the drivers completely solved this problem. Let us also mention that these routers can occupy one or two channels. At the same time, the D-Link device is configured by default to work with a 20 MHz channel, while Netgear and Edimax models are configured with a dual channel. For measuring maximum performance We, of course, used the 40 MHz mode, but in this case the performance of other wireless networks in the immediate vicinity may be degraded. By the way, before discussing performance, let us remind you that before the advent of Wi-Fi networks The 2.4 GHz range belonged to the so-called garbage bands (garbage bands) due to the large number of interference of a very different nature, and since then the situation, if it has changed, is not in better side. And to a certain extent, this can explain the significant differences in the speed of data transfer from one measurement to another. Of course, in order to reduce the random error of measurements, we made quite a lot of them and carried out appropriate statistical processing of the results. But in any case, we can confidently say that the arguments that occur from time to time that one device is better than another because its file copying speed was several megabits per second higher are simply meaningless without repeated measurements and the necessary processing of the results .

Average data transfer rates over the TCP/IP protocol are presented in Diagram 1, after studying which we can draw the following conclusion: on average, the connection speed over 802.11n is about 50 Mbit/s, which is approximately 2.5 times higher than the connection speed over 802.11g . In addition, although, as you would expect, using an access point and adapter from the same manufacturer leads to the best speed performance, devices from all three manufacturers demonstrate fairly good compatibility with each other.

In the second series of tests, we measured the speed of a wireless network near a strong source of interference, which was a working microwave oven. The results obtained speak for themselves: if for a standard 802.11g connection the speed drops by an order of magnitude and is about 2 Mbit/s, then devices corresponding to 802.11n demonstrate stable operation with an average speed of more than 10 Mbit/s, i.e. at least 5 times faster.

Accordingly, based on a series of measurements, we come to the conclusion: 802.11n devices provide a real connection speed via the TCP/IP protocol of about 50 Mbit/s, demonstrating significantly better job wireless network in case of strong interference, and in addition, the device different manufacturers(at least three - D-Link, Netgear and Edimax) already interact quite well with each other.

How we tested

A computer based on an Intel Extreme Edition 955 processor with 1 GB of RAM and a WD4000KV hard drive, running under Windows control XP SP2. Using a wireless connection, I connected to the access point Acer laptop TravelMate 3300 running Windows XP SP2, equipped Intel processor Pentium M 1.7 GHz, 512 MB RAM and Hitachi TravelStar 4K120 hard drive. Connection speed was measured using the Netperf package (www.netperf.org). To evaluate the performance of the wireless network, the transmission speed of the downlink data stream (downlink) TCP/IP from desktop computer to the laptop. The downstream connection speed when connecting computers via a 1 Gbit/s Ethernet network was about 350 Mbit/s. When setting up the access point, the frequency channel was selected that was the most distant from other signal sources and, accordingly, provided maximum throughput. To exclude the possible influence of the location of the access point and other random factors, each measurement was carried out 20 times.

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).

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

At the 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 (currently these devices are already 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" before "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.

There are several types of WLAN networks, which differ in the signal organization scheme, data transfer rates, network coverage radius, as well as the characteristics of radio transmitters and receiving devices. The most widely used wireless networks are IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac and others.

The 802.11a and 802.11b specifications were the first to be approved in 1999, however, devices made according to the 802.11b standard are the most widespread.

Wi-Fi standard 802.11b

Standard 802.11b based on the Direct Sequence Spread Spectrum (DSSS) modulation method. The entire operating range is divided into 14 channels, spaced by 25 MHz to eliminate mutual interference. Data is transmitted over one of these channels without switching to others. Only 3 channels can be used simultaneously. The data rate may change automatically depending on the level of interference and the distance between the transmitter and receiver.

The IEEE 802.11b standard implements a maximum theoretical transfer rate of 11 Mbps, which is comparable to cable network 10 BaseT Ethernet. Please note that this speed is possible when transmitting data with one WLAN device. If a larger number of subscriber stations operate simultaneously in an environment, the bandwidth is distributed among all and the data transfer rate per user drops.

Wi-Fi standard 802.11a

Standard 802.11a was adopted in 1999, however, it found its application only in 2001. This standard is used mainly in the USA and Japan. It is not widely used in Russia and Europe.

The 802.11a standard uses a signal modulation scheme - Orthogonal Frequency Division Multiplexing (OFDM). The main data stream is divided into several parallel sub-streams at a relatively low bit rate, and then an appropriate number of carriers are used to modulate them. The standard defines three mandatory data transfer rates (6, 12 and 24 Mbit/s) and five additional ones (9, 18, 24, 48 and 54 Mbit/s). It is also possible to use two channels simultaneously, which increases the data transfer speed by 2 times.

Wi-Fi standard 802.11g

Standard 802.11g was finally approved in June 2003. It is a further improvement of the IEEE 802.11b specification and implements data transmission in the same frequency range. The main advantage of this standard is increased throughput - the data transfer rate in the radio channel reaches 54 Mbit/s compared to 11 Mbit/s for 802.11b. Like IEEE 802.11b, the new specification operates in the 2.4 GHz band, but to increase speed it uses the same signal modulation scheme as 802.11a - orthogonal frequency division multiplexing (OFDM).

The 802.11g standard is compatible with 802.11b. Thus, 802.11b adapters can work on 802.11g networks (but not faster than 11 Mbps), and 802.11g adapters can reduce the data transfer rate to 11 Mbps to work on older 802.11b networks.

Wi-Fi standard 802.11n

Standard 802.11 n was ratified on September 11, 2009. It increases the data transfer rate by almost 4 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. The maximum theoretical data transfer rate is 600 Mbit/s, using data transmission over four antennas at once. One antenna – up to 150 Mbit/s.

802.11n devices operate in the frequency ranges of 2.4 – 2.5 or 5.0 GHz.

The IEEE 802.11n standard is based on OFDM-MIMO technology. Most of the functionality is borrowed from the 802.11a standard, however, the IEEE 802.11n standard has the ability to use both the frequency range adopted for the IEEE 802.11a standard and the frequency range adopted for the IEEE 802.11b/g standards. Thus, devices that support the IEEE 802.11n standard can operate in either the 5 GHz or 2.4 GHz frequency range, with the specific implementation varying by country. For Russia, IEEE 802.11n standard devices will support frequency range 2.4 GHz.

An increase in transmission speed in the IEEE 802.11n standard is achieved by doubling the channel width from 20 to 40 MHz, as well as due to the implementation of MIMO technology.

Wi-Fi standard 802.11ac

The 802.11ac standard is a further development of the technologies introduced in the 802.11n standard. In the specifications, 802.11ac devices are classified as VHT (Very High Throughput) - with veryhigh throughput. 802.11ac networks operate exclusively in the 5 GHz band. The radio channel band can be 20, 40, 80 and 160 MHz. It is also possible to combine two 80 + 80 MHz radio channels.

Comparison of 802.11n and 802.11ac

Sources:

1. A.N. Steputin, A.D. Nikolaev. Mobile communications on the way to 6G . In 2 T. – 2nd ed. - Moscow-Vologda: Infra-Engineering, 2018. – 804 p. : ill.

2. A.E. Ryzhkov, V. A. Lavrukhin Heterogeneous radio access networks: tutorial. - St. Petersburg. : SPbSUT, 2017. – 92 p.

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 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 wireless adapter, which has an antenna and connects to the PCI connector of the computer (internal adapter) or USB connector (external adapter). For laptops can be used as external USB adapters, and adapters for the PCMCIA connector; in addition, many laptops are initially equipped with a Wi-Fi adapter. Interaction of computers and portable systems equipped with Wi-Fi adapters, is provided by an access point, which can be considered analogous to 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 compatible 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 universal availability and low price. There are also significant disadvantages, such as low speed data transfer (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 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 enough for any apartment, but for a larger room the use of wireless communication of this standard may not be acceptable.

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, faxes, 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 “ “.