WiFi coverage area. Wifi routers radius and range

From time to time we all face the problem of insufficient signal strength from the router. The signal is unstable at some points, often disappears or does not exist at all. This is noticeable in rooms with a large area: in a country house, in a private house, at a recreation center, in an apartment with more than one room. In this article we will describe options to solve this problem.

Figure 1. WiFi coverage area of ​​a router in a typical apartment (router next to the front door).

We produce passive and active antennas, including for data transmission networks and WiFi. In this article we are interested not so much in the problems of wireless access, but in ways to increase the WiFi coverage area. Note that we are not considering specific options for creating special “powerful” access points. Everything is within the framework of the standards and norms adopted in the Russian Federation.

In our experience, the router is usually placed: next to the front door, in the corridor behind the closet, or in the distribution panel. In such cases, the area of ​​the apartment is covered unevenly by the WiFi network. Depending on the layout of the apartment, the back rooms, kitchen, loggia are outside the zone of stable coverage. (Example in Figure 1)

The same situation is true for a private house. The area of ​​the house is usually larger, and the Internet is needed not only indoors, but also outside - near the barbecue area, swimming pool, or on the playground. Here the problem is more serious.

Figure 2. WiFi coverage area of ​​a router in a country house

Figures 1 and 2 show examples of WiFi coverage; zones with a good network level are highlighted in green, zones with a low level are highlighted in red, which often does not allow normal work on the Internet. Please note that the WiFi signal, being a radio wave, travels better in free space, so walls and other partitions in the room will weaken it and, as a result, reduce the level of the signal passing through them.

The problem has been identified - insufficient WiFi network coverage indoors. Let's figure out why this happens. The standard antenna of the router has a circular radiation pattern - it emits WiFi in all directions. Including in the direction of your neighbors, which is usually pointless and unnecessary. At the same time, the antenna’s own gain is relatively low, as a result of which such an antenna is insufficiently efficient. As a result, the WiFi signal coverage area is small.

Figure 3. Radiation pattern of the standard router antenna (f=2.45 GHz)

Figure 3 shows the radiation pattern of the external antenna of a standard router, calculated in the physical simulator. A dipole is used as an antenna.

How to Improve WiFi Coverage

The first thing that comes to mind is to replace the router with another one. Buy a device with a more powerful external antenna or with several antennas. If you have an outdated router model, then it's worth a try. Be prepared that this will require additional costs, and a positive result is not at all guaranteed. Most likely the picture will improve, but the problem will not be eliminated (Fig. 4-5).

Figure 4. Router with two external antennas.

Figure 5. Router with three external antennas.

The next method is to use an active WiFi repeater, also called a WiFi repeater. This device is specifically designed to increase the range of a WiFi network. An excellent way that often allows you to solve the problem at the root. But it also has disadvantages:

— prices from one and a half thousand rubles and above;
— need for customization;
- limited area of ​​use.

And that’s not all: the repeater will again receive the signal from all directions and radiate it around. That is, if we have an “uncovered” corner of the apartment far away, then we will need two or even three repeaters. It would be great to concentrate the signal in a given direction, but it won’t work - the built-in antennas of repeaters have a circular diagram. We have not seen repeaters with a socket for an external antenna.

It is worth mentioning another feature of the WiFi repeater - the presence of a 220V mains power supply. Not all people are ready to leave some devices plugged in when leaving home. And turning it on and off every time is an amateur job. In addition, for a home or cottage, the decision is complicated by the fact that there is most often no power supply between the house and, say, a barbecue area, and repeaters are often not intended for outdoor use.

Figure 6. How the WiFi repeater works

The next solution is to use an external directional antenna. The simplest thing is to unscrew the standard antenna from the router and connect a directional one, which will focus the entire signal in the desired direction. There are a lot of antennas of this kind, but we will focus on the developments of our enterprise.

The first solution is the WiFi Extender antenna (Figure 7):

Figure 7. WiFi Extender Antenna

This is an indoor antenna of the “wave channel” type in a radio-transparent plastic case. Antenna gain 10 dBi.

The second option is more complex and effective - a panel antenna. In our case - BAS-2301 WiFi (Figures 8-9). Inside the radio-transparent sealed case is a patch antenna. Gain of at least 12.5 dBi.

Figure 8. BAS 2301 WiFi antenna

Figure 9. Radiation pattern of the BAS 2301 WiFi antenna (f=2.45 GHz)

The third option is a “wave channel” antenna for the WiFi range (2400-2500 MHz). In the REMO version, this is the BERKUT WiFi antenna (Figure 10). There are already 19 elements (6 of them are placed in a box on a printed circuit board), the maximum directional gain is 15 dBi.

Figure 10. Berkut WiFi antenna

All the methods mentioned above will most often solve the problem. WiFi will appear in the right place, and with an excellent signal level. But there are some nuances here:

- The price of the issue. These antennas are cheaper than a repeater, but their price is above 1000 rubles.
- Installation. All such antennas require installation. The bracket needs to be installed. If you live in a rented apartment, then obtain permission from the owner to secure this structure. Also, this may entail some inconvenience if you do not have the opportunity to mount the bracket on the wall yourself. I think the reader understands that it is not always possible to secure the bracket for various reasons, even despite the simplicity of this procedure.
— Accommodation. If in a house or cottage you can install an antenna outdoors by running only a cable inside, then for an apartment this is not a suitable option.

Another limitation on the use of such antennas is that not all routers have an antenna connector for connecting external antennas. The middle and budget segments often have non-detachable antennas and, as a result, the above-mentioned solutions are not suitable for such routers by definition.

Therefore, remote antennas are a good solution, but not applicable in all cases. What else can you do to increase your WiFi network coverage?
We have been asking this question for a long time. What could you come up with that would be applicable in almost all cases, would be effective, inexpensive and simple?

The reader may be familiar with our popular modem product Connect 2.0 or its older versions.
The principle of operation is simple - using the device’s (modem) own internal antenna as an active element of the antenna system. So, in a simplified way, you can imagine the entire series of “Internet signal amplifiers”.

We thought - is it possible to apply the same principle in a WiFi router with an external antenna?

Figure 11. Connect 2.0 Antenna

Development of an antenna attachment for a router (WiFi Ladder)

So, we have a router with an external antenna (important: we do not consider routers with a built-in antenna). The question arises: how to use this own antenna as an active element (vibrator) of the antenna system? Our goal is to give directional properties to the external antenna of the router, which will entail an increase in the range of transmission and reception of the WiFi signal in a given direction. The first thing that comes to mind is the “wave channel” antenna, also known as “UDA-YAGI” (after the names of its inventors from Japan). This is a simple and at the same time effective antenna design that has proven itself throughout the world.

So an idea appeared and it had to be translated into a design. The developers were faced with the task of calculating a multi-element wave channel for the 2.4-2.5 GHz range, into which it would be possible to “implement” the standard antenna of the router. During the simulation, it was decided that the best option would be a 7-element “wave channel”. With quite compact dimensions of the structure, we received an antenna system, the amplification of which allows us to solve the assigned problems. The dimensions of the directors and the distances between them were optimized in the physical model; we consider them the best for solving the problem (Fig. 12).

Figure 12. “Stuffing” of the BAS-2002 WiFi Ladder antenna

The next stage was the development of the antenna mounting design. After monitoring the router market, we decided to place a “wave channel” on the external antenna of the router, using it as a supporting element (Fig. 13). We are faced with the fact that routers have antennas of different diameters, and sometimes their shape is far from cylindrical or conical. For example, a “flattened” external antenna is very popular. For this reason, the designers have developed a universal clamp that allows you to mount the product on almost any external antenna of the router. In some cases, this will not be the most rigid mount, but we would like to note that the antenna is usually installed indoors and only once, so third-party physical impacts on it will be minimal.

Figure 13. BAS-2002 WiFi Ladder antenna mounted on the external antenna of the router

A series of tests were carried out, during which the “shaded” areas of the room became covered by WiFi, and with a decent level (Fig. 14). The area with a good WiFi signal level is highlighted in green in the figure.

Figure 14. WiFi coverage area of ​​a router with an antenna attachment
BAS-2002 WiFi Ladder in a typical apartment

Below is the radiation pattern of the developed antenna, which is attached to the external antenna of a typical router (Fig. 15).

Figure 15. Radiation pattern of the external antenna of the router with the BAS-2002 WiFi Ladder antenna attachment

The router antenna acquired directional properties and, as a result, directional gain, resulting in an increase in the range of WiFi signal transmission in a given direction. In red in Fig. Figure 15 shows the maximum antenna radiation - the direction in which the WiFi network coverage area will increase.

During development, the working name firmly attached to the antenna - “ladder”, therefore, without thinking twice, we decided to name this product, translating only into English, taking into account our export practice: “BAS-2002 WiFi Ladder”.

One more question cannot be ignored: where should the product be mounted on the external antenna?

Having studied the designs of external antennas of different routers, we came to the conclusion that the antennas inside the plastic case are not always located as we expect (Figure 16).

Figure 16. “Inside” of one of the external antennas of the router.

As can be seen from Figure 16, the antenna is not located along the entire length of the plastic case, but only in its lower part.

Most often, the antenna structure is located in the lower or middle part of the plastic housing. That is why the user needs to find the optimal height location for mounting on an external antenna (Fig. 17). It happens that the user forgets or ignores this important setting point and does not get the expected result, so let us remind you once again - height adjustment is important and mandatory!

Figure 17. Adjusting the BAS-2002 WiFi Ladder antenna height

The antenna operates in IEEE802.11 b/g/n standard networks using frequencies of 2.4..2.5 GHz.

As we said earlier, there are routers with multiple external antennas. In this case, you can use the antenna attachment for all antennas or just one or two. Depends on the tasks. You can create maximum gain in one direction, then all antennas will be “aimed in one direction” and their gain will add up (Fig. 18).

Figure 18

You can strengthen WiFi in different directions, i.e. expand coverage area:

Figure 19

It is worth mentioning programs that will help you adjust the direction of such antennas (not only WFi LADDER).

Each router has its own maximum range, initially set by the manufacturer. But usually the router does not work at full capacity for some reason. Its capabilities can be increased not only by reconfiguration, but also by additional equipment.

What determines the strength and range of the signal?

All modern router models have the same operating principle. There are two main characteristics of the signal:

• force - the maximum speed of receiving and sending bits per second;
• range - the distance from the router at which you can catch a stable Wi-Fi signal.

For all routers, the signal strength and range are affected by the following factors:

• speed of the supplied Internet connection. It affects the maximum possible speed of the Wi-Fi network. The router cannot transmit data to the Internet faster than an Internet cable or Internet modem. At the same time, the maximum Wi-Fi speed is sometimes lower than the maximum Internet connection speed;
• maximum throughput. The router is a router, that is, it redirects incoming and outgoing data to the desired stream, but the speed of sorting information is limited. In most cases, it is higher than the maximum Internet connection speed, but in cheap or older models it may not be sufficient;
• router settings. There are several characteristics, discussed in a separate paragraph, that affect signal quality;
• antenna. It plays the most important role in signal propagation. It determines how far and in what direction the signal will be heard;
• receiver. Each device has a built-in Wi-Fi receiver and a small antenna. If you don't have enough signal strength, it may be the device and not the router. It may have a receiver installed that is too weak or an antenna that is not powerful enough to receive an average Wi-Fi signal.

The speed of the connected Internet connection and the maximum throughput of the router cannot be changed in any way without replacing the equipment. But other parameters can be adjusted manually, thereby achieving maximum effect.

Video: how to strengthen the Wi-Fi signal

How to improve your signal without buying equipment

There are several ways you can change signal characteristics for the better without having to buy new equipment. Let's consider them in order of increasing complexity and time-consuming implementation.

Moving the router

If you have the opportunity, move your router to the place where you spend the most time on the Internet. Since most routers have a circular antenna installed, they distribute the signal over a certain radius around themselves. And the further the distance from the center, that is, from the router, the weaker the signal. It does not stop abruptly, but decreases gradually until it becomes too weak for stable transmission of information.

The signal is heard in all directions

Changing the location of the router can also help if the Internet connection is via a modem. Perhaps in a new location the modem will catch the signal better, which means the connection speed and Wi-Fi network will increase.

Setting up the router

The network distributed by the router has two characteristics that can be changed in any router model:

• a channel is a specific frequency at which the network operates. If you live in an apartment building or are in an office with several routers, they may coincide, several routers will work in the same channel. As a result, the signal speed will drop due to the fact that the router will have to filter signals intended for other routers;
• frequency - modern routers can operate in two types of frequencies (2.4 GHz and 5 GHz). Most often, the first version is used by default, but some models allow you to switch to the second. Since most routers operate in the 2.4 GHz band, after switching to another mode the amount of interference will decrease. It should be taken into account that 5 GHz is suitable for distributing a signal over long distances, but in a small room, especially in the presence of obstacles, it can lose quality. Only by experience, by checking the speed and range of the signal at both frequencies, can you find out which option is better in your case.

Some models allow you to manually adjust the signal strength. Sometimes this parameter is set as a percentage, and sometimes in three values: low, medium, high.

Search for used channels

In Russia, you are allowed to use 13 channels (from 1 to 13 for 2.4 GHz), in America - 11. Therefore, the channel number available to you will be limited by your country of residence. Be sure to check this information before changing the channel. After setting a prohibited value, the device will not be able to connect to the network.

Before changing the channel, you need to understand whether it is worth doing and which channel you can switch to. To do this, follow these steps:

Change channel

Having found out which channel is least loaded, you can proceed to setting up the router. It will be carried out through the control panel, accessible from any device connected to a Wi-Fi network or via a LAN cable to the router:

Frequency change

If your router supports frequency change, then in the control panel this function can be found in the wireless network settings. To activate a 5 GHz Wi-Fi network, you need to switch to one of the following channels: 36, 40, 44, 48 (data for Russia, may differ in other countries).

Choosing what frequency the router should operate at

After switching to a new frequency, check whether the Internet has become more stable and faster, and whether the range of access to the network has increased.

Power change

Some models allow you to change the signal strength in the router control panel. If this item is in the settings of your model, then set the maximum available value.

We indicate the maximum power

After changing the settings, save the entered information and reboot the router.

Disable Power Saving

This item concerns setting up a device connected to the network. If the battery saving mode is activated on a laptop, phone or tablet, this may affect the stability of signal reception.

Since working with a Wi-Fi network requires a lot of energy, when energy saving is activated, the device tries to stop exchanging information over the network at any convenient opportunity. Because of this, Internet speed may drop.

Windows

To deactivate the power saving mode in Windows 10, click on the battery icon located in the lower right corner of the quick access panel. In the expanded block, move the slider towards maximum performance. It is not necessary to set the maximum value, the main thing is that the maximum operating mode is not activated.

Moving the slider towards performance

Android

Swipe down from top to bottom of your device screen. Find the battery icon. If the mode is activated, the icon will turn red or turn into a battery with a plus (depending on the firmware version). Click on the icon to deactivate the mode.

Click on the battery icon to deactivate the power saving mode

iOS

To deactivate the mode on the iOS operating system, you need to perform the following steps:

How to improve your signal with new equipment

To solve the problem, you can resort to replacing some components or purchasing additional devices.

Replacing the receiving device

Study the characteristics of the device from which you connect to the Wi-Fi network. Information can be found on the developer's official website or in the documentation that comes with the device.

The manufacturer may have installed a bad Wi-Fi receiving adapter or a weak antenna. By reading reviews, you can find out if anyone has encountered a similar problem. If the model has a problem with the adapter or antenna, it will be possible to replace these components by installing higher quality components.

You can replace the device antenna

But you should only replace components if you have sufficient experience in this. Replacing the internals will void the device warranty. If you are not confident in your abilities, contact the service center.

Antenna replacement

The antenna's job is to distribute and receive a response signal. The distribution range depends on the power of the antenna, and the sector into which the signal will be received depends on the direction. There are two types:

You can buy a more powerful circular antenna if you want the signal to be heard in all directions. This is convenient if the router, for example, is located on the second floor, but devices from the first floor, and from the third, and from rooms located on opposite sides of the router are connected to it.

If you have the opportunity to position the router so that all devices are located in one line relative to it, then you can purchase a directional antenna. This way you will achieve a high signal propagation range.

Antenna modification

If you don’t want to buy a new antenna, you can remake an existing one or make a new one yourself. There are instructions on the Internet for different models and descriptions of how to make an antenna from scratch. There is no universal method, since it is necessary to take into account the characteristics of each router, the conditions in which it will be located, the tasks it faces, as well as other characteristics of the antenna: length, width, material of manufacture, shape.

For example, you can make a special nozzle from pumpan foam or a wooden plank and nails. This attachment turns a circular antenna into a directional one, so the signal in a certain direction is amplified and weakened in others (see paragraph “Replacing the antenna”).

The nozzle should be made, observing the dimensions

Buying repeaters

A repeater (or repeater, or access point) is a device that forwards a Wi-Fi signal sent by someone. The repeater catches the signal from the router and distributes it around itself with increased strength, that is, it relays it further.

It is convenient to use a repeater if the distributed network does not reach some point in your home or office. By installing a repeater at the extreme edge of the Wi-Fi signal, you will extend the range of the main Wi-Fi network. Setting it up is simple: one button is pressed simultaneously on the router and on the repeater, after which the devices are connected, and from that moment they begin to work in pairs.

Some routers have a “Boost” feature that turns the router into a repeater. If you have two routers, you can make one a Wi-Fi point, that is, leave it as a router, and turn the second into a repeater.

When buying an access point, you need to consider the compatibility of the router with this repeater model. It is recommended to purchase a repeater and router from the same manufacturer. For example, if you have a TP-Link router, then it is better to buy a TP-Link repeater.

Video: how to strengthen the signal through a repeater

There are many ways to improve your wireless network signal. If you don’t buy equipment, you can achieve results by changing the router settings, moving the device, or turning off the battery saving mode. With a small investment, you can replace the components of the receiving device, the router antenna, or purchase a repeater.

When choosing a wireless router, many are interested in the question of whether its power is enough for a large apartment or house, and whether there will be “dead zones” where Wi-Fi cannot be received. Let's figure out how to choose a router with a long range.

The answer is obvious - choose a powerful Wi-Fi router with a long range. Just keep in mind that the receiver (laptop, tablet or TV) must also respond well to the signal.

What parameters should I pay attention to?

When choosing a router, pay attention to the operating standards of the device, the main ones:

11b – data transfer speed up to 11 Mbit/s
11g – data transfer speed up to 54 Mbit/s
11n – data transfer speed up to 600 Mbit/s
11ac - data transfer speed up to 6 Gbps

Number of antennas

The more antennas, the better. They can be external and internal. Thanks to antennas, you can get a wide signal coverage area. It is better to choose a router with removable antennas; if you want to increase the range, replace them with more powerful ones, for example 8 - 12 dbi.

frequency range

There are two bands in which wireless routers operate – 2.4 GHz and 5 GHz. Cheaper models have one frequency range - 2.4 GHz (it is very crowded, especially in apartment buildings).

If the device operates in two bands, the overall throughput increases. In this case, you can select a less crowded channel. But keep in mind that the receiving device must also be able to operate in 5 GHz mode.

Which brand of router should you choose?

All popular brands of routers with one antenna Asus, TP-Link, D-link have almost similar characteristics:

• frequency range 2.4 GHz;
• antennas 2-5 dbi;

These indicators are enough for a reliable WI-FI signal throughout the apartment. The cost of routers with one antenna starts from 400 UAH, with two - from 700 UAH.

Routers with two and three antennas can have two operating bands and some additional functions; their technical characteristics are the same as those described above.

Expensive Wi-Fi routers

• Zyxel Keenetic Ultra II
• TP-LINK TL-WDR3600
• Asus RT-AC3200

as well as products from Linksys, Cisco, Mikro Tik.

In a large private house or office, budget routers will not cope with the task; in order to cover the maximum area, repeaters must be used. But it is better to choose a more expensive router model with good characteristics. Such devices use a more powerful transmitter, enhanced antennas and hardware, which allows you to transmit a signal over a distance of up to 100 meters, connect a large number of users to the Internet, and also watch video in excellent quality on Smart TV.

High-end routers are used by gamers because they have minimal packet loss and can connect to the Internet at speeds of more than 1 Gbit/s.

Now in Ukraine you can buy a good router for 3000-7000 UAH. The price is not always justified, since some models are crammed with functions that are unnecessary for the average user. An indisputable advantage is the presence of a port for connecting a modem with 3G or 4G Internet. This is useful when cable Internet does not work or cannot be connected.

The big disadvantage of these models is that not many people can configure the device correctly. Internet service providers most often come across companies like TP-LINK, Asus, D-Link, but many don’t know how to set up a router from another company.

What determines the router signal transmission distance?

The signal range in both regular and powerful Wi-Fi routers depends on some features:

• barriers (brick or concrete walls with reinforcement, trees)
• antenna directivity
• interference from radio and household appliances (for example, microwave)
• channel congestion
• router firmware version

What should I do to improve the quality and range of reception?

The coverage area depends on where the router is installed and how the antennas are directed. Try to place the device in the center of the apartment or house. If Wi-Fi is not needed throughout the entire area, but only in a separate room, but it is not possible to install a router there, then make reflectors from foil and put them on the antennas. You can also replace standard antennas with directional ones.

WiFi(read “wifi” with emphasis on the second syllable) is the industrial name for wireless data exchange technology, belonging to the IEEE 802.11 group of wireless networking standards. To some extent, the term Wi-Fi is synonymous with 802.11b, since 802.11b was the first standard in the IEEE 802.11 group of standards to become widespread. However, today the term Wi-Fi equally refers to any of the 802.11b, 802.11a, 802.11g and 802.11n, 802.11ac standards.

The Wi-Fi Alliance certifies Wi-Fi products to ensure that all 802.11 products placed on the market meet the standard's specifications. Unfortunately, 802.11a, which uses the 5GHz frequency, is not compatible with 802.11b/g, which uses the 2.4GHz frequency, so the market for Wi-Fi products remains fragmented. For our country, this is not relevant, since the use of equipment of the 802.11a standard requires special permission and it is not widely used here; moreover, the vast majority of devices that support the 802.11a standard also support the 802.11b or 802.11g standard, which allows us to consider All WiFi devices currently sold are relatively compatible. The new 802.11n standard supports both of these frequencies.

What equipment is needed to create a wireless network?

Each device that participates in a wireless network requires a wireless network adapter, also called a wireless network card. All modern laptops, some desktop computers, smartphones and tablets already have built-in wireless network adapters. However, in many cases, to create a wireless network of desktop computers, network adapters must be purchased separately. Popular network adapters for laptops are made in the Mini PCI-E or M.2 device format; respectively, for desktop computers there are models with the PCI, PCI-E interface; wireless USB adapters can be connected to both portable and desktop systems.

To create a small wireless local network of two (in some cases, more) devices, it is enough to have the required number of network adapters. (They are required to support AdHoc mode). However, if you want to increase the performance of your network, connect more computers to the network, and extend the range of your network, you will need wireless access points and/or wireless routers. The functions of wireless routers are similar to those of traditional wired routers. They are usually used in cases where a wireless network is created from scratch. An alternative to routers are access points, which allow you to connect a wireless network to an existing wired network. Access points are used, as a rule, to expand a network that already has a wired switch or router. To build a home local network, one access point is enough, which is quite capable of providing the required range. Office networks typically require multiple access points and/or routers.

Access points and routers, PCI/PCI-E network cards and some USB adapters can be used with more powerful antennas instead of standard ones, which significantly increases the communication range or coverage range.

	Adapters	Access points	Other
Network of two wireless devices without connection to a local wired network	2	-	Network adapters must support Ad-Hoc mode; in some cases, more than two devices can be networked this way.
Small home or office network of	By number of devices	1	If you plan to connect wired devices to the local network, then you need an access point with the functionality of a router (Wireless Router).
Bridge between wired LANs	-	Based on the number of networks, if there are more than two, you need to make sure that the selected access points support Point-To-MultiPoint Bridge mode	-
Organization of a large wireless office or corporate network	By number of devices	The quantity is selected based on the optimal coverage area and operating speed.	Some access points can operate in repeater or WDS mode.

What is the standard range of a Wi-Fi network?

The range of your home Wi-Fi network depends on the type of wireless access point or wireless router you use. Factors that determine the range of wireless access points or wireless routers include:

The type of protocol used is 802.11;
. Total transmitter power;
. Gain of the antennas used;
. Length and attenuation in the cables that connect the antennas;
. The nature of obstacles and interference in the signal path in a given area.

The range with standard antennas (usually 2dBi gain) of popular 802.11g access points and routers, provided they are connected to a device that has an antenna with the same gain, can be approximately estimated at 150m in open areas and 50m indoors, more accurate The figures for the different standards are shown in the table below for baud rates.

Obstacles in the form of brick walls and metal structures can reduce the range of a Wi-Fi network by 25% or more. Because 802.11a/ac standards use higher frequencies than 802.11b/g standards, it is the most sensitive to various types of obstacles. The range of Wi-Fi networks that support 802.11b or 802.11g is also affected by interference from microwave ovens. Below is a table showing the approximate loss of efficiency of a 2.4 GHz Wi-Fi signal when passing through various obstacles.

Another significant obstacle can be the foliage of trees, since it contains water that absorbs microwave radiation in this range. Heavy rain attenuates signals in the 2.4 GHz range with an intensity of up to 0.05 dB/km, dense fog introduces an attenuation of 0.02 dB/km, and in a forest (thick leaves, branches) the signal can attenuate with an intensity of up to 0.5 dB/meter.

You can increase the range of a Wi-Fi network by combining several wireless access points or routers into a chain, as well as by replacing the standard antennas installed on network cards and access points with more powerful ones.

Approximately possible options for the range and speed of the network, ideally, can be calculated using a special calculator aimed at D-Link equipment, but the formulas and methods used there are suitable for any other.

When creating a radio bridge between two networks, you need to be aware of the fact that the space around the straight line drawn between the receiver and transmitter must be free of reflecting and absorbing obstacles within a radius comparable to 0.6 of the radius of the first Fresnel zone. Its size can be calculated based on the following formula:

In a real situation, the signal level at different distances from the transmitting device can be measured using a special device.

What is networking in Infrastructure mode?

This mode allows you to connect a wireless network to a wired Ethernet network via a wireless access point. For connection to be possible, the wireless local area network (WLAN), wireless access point, and all wireless clients must use the same SSID (Service Set ID). Then you can connect the access point to a wired network using a cable and thus provide wireless clients with access to wired network data. In order to expand the infrastructure and provide simultaneous access to the wired network to any number of wireless clients, you can connect additional access points to the wireless LAN.

The main advantages of networks organized in Infrastructure mode compared to networks organized in Ad-Hoc mode are their scalability, centralized protection and extended range. The downside, of course, is the cost of purchasing additional equipment, such as an additional access point.

Wireless routers designed for home use are always equipped with a built-in access point to support Infrastructure mode.

How fast can a wireless network be?

The speed of your wireless network depends on several factors. The performance of wireless LANs is determined by which Wi-Fi standard they support. Networks that support the 802.11ac standard can offer maximum throughput - up to 2167 Mbit/s (using MU-MIMO). The throughput of networks supporting the 802.11a or 802.11g standard can be up to 54 Mbps. (Compare with standard wired Ethernet networks, which have 100 or 1000 Mbps bandwidth.)

In practice, even with the highest possible signal level, the performance of Wi-Fi networks never reaches the above theoretical maximum. For example, the speed of networks supporting the 802.11b standard is usually no more than 50% of their theoretical maximum, i.e. approximately 5.5 Mbps. Accordingly, the speed of networks that support the 802.11a or 802.11g standard is usually no more than 20 Mbit/s. The reasons for the discrepancy between theory and practice are protocol coding redundancy, signal interference, and changes in the Hamming distance with changes in the distance between the receiver and transmitter. In addition, the more devices on the network simultaneously involved in data exchange, the proportionally lower the network bandwidth per device, which naturally limits the number of devices that make sense to connect to one access point or router (another limitation may be caused by the characteristics of operation of the built-in DHCP server, for devices from our range the final figure was in the range from 26 to 255 devices).

Protocol	Frequency used	Maximum theoretical speed	Typical speed in practice	Indoor communication range	Communication range in open areas
802.11b	2.4GHz	11Mbit/sec	0.4MB/sec	38	140
802.11a	5GHz	54Mbps	2.3MB/sec	35	120
802.11g	2.4GHz	54Mbps	1.9MB/sec	38	140
802.11n	2.4GHz, 5GHz	600Mbit/sec	7.4MB/sec	70	250

In addition, the speed of any pair of devices drops significantly as the signal level decreases, so often the most effective way to increase the speed for remote devices is to use antennas with high gain.

Is wireless communication safe for health?

Recently, there has been a lot of talk in the media that prolonged use of wireless network devices can cause serious illnesses. However, to date, there is no scientific data that would confirm the assumption that microwave signals have a negative impact on human health.

Despite the lack of scientific data, we dare to suggest that wireless networks are safer for human health than mobile phones. The frequency range of a typical home wireless network is the same as that of microwave ovens, but microwave ovens and even cell phones are 100 to 1000 times more powerful than wireless network adapters and access points.

In general, one thing can be stated with confidence in this matter: the intensity of human exposure to microwave radiation from wireless networks is incomparably less than the impact of other microwave devices.

The procedure for registering radio electronic devices is described in Decrees of the Government of the Russian Federation dated October 12, 2004 No. 539 “On the procedure for registering radio-electronic equipment and high-frequency devices” and dated July 25, 2007 No. 476 On amendments to the Decree of the Government of the Russian Federation dated October 12, 2004. No. 539 "On the procedure for registration of radio-electronic equipment and high-frequency devices"

According to Resolution N 476 of July 25, 2007, user (terminal) radio access equipment (wireless access) in the radio frequency band 2400 - 2483.5 MHz with a transmitting device radiation power of up to 100 mW inclusive is EXCLUDED from the list of radio electronic equipment and high-frequency devices subject to registration.

We remind you that the standard transmitter power of all currently sold consumer WiFi devices is within this figure, and the installation of any antennas that do not have active elements does not increase it.

Access point operating modes Access Point Mode

(Access Point) - Access Point mode is designed to wirelessly connect laptops, desktops, smartphones and tablets to an access point. Wireless clients can access the access point only in Access Point mode. Access Point Client/Wireless Client Mode

(Wireless Client) - AP Client or Wireless Client mode allows an access point to become a wireless client of another access point. Essentially, in this mode, the access point performs the functions of a wireless network adapter. You can use this mode to exchange data between two access points. Communication between the wireless card and the access point is not possible in Access Point Client / Wireless Client Mode. Point-to-Point / Wireless Bridge

Point-to-Multipoint / Multi-point Bridge(Wireless point-to-multipoint bridge) - Point-to-Multi-point / Multi-point Bridge mode is similar to Point-to-point / Wireless Bridge mode with the only difference being that it allows the use of more than two access points. Wireless clients also cannot communicate with the access point in this mode.

Repeater Mode(Repeater) - Operating in wireless repeater mode, the access point extends the range of the wireless network by repeating the signal from the remote access point. In order for an access point to perform the functions of a wireless range extender for another access point, it is necessary to specify the Ethernet MAC address of the remote access point in its configuration. In this mode, wireless clients can exchange data with the access point.

WDS(Wireless Distribution System) - allows you to simultaneously connect wireless clients to points operating in Bridge (point-to-point bridge) or Multipoint Bridge (point-to-multipoint bridge) modes, but this reduces the operating speed.

All access points and wireless routers currently sold are easily configured via a web interface, for which you need to access the specific IP address specified in the documentation for the device when connecting them to your network for the first time. (In some cases, special TCP/IP protocol settings will be required on the computer used to configure the access point or router, also specified in the documentation)

Equipment from many manufacturers is also equipped with special software, including for mobile devices, which makes the setup procedure easier for users. The specific information necessary to configure the router to work with your provider can almost always be found on the provider’s website.

Security, encryption and user authorization in wireless networks.

Initially, to ensure security in 802.11 networks, the algorithm was used WEP(Wired Equivalent Privacy), which included an RC4 encryption algorithm with a 40-bit or 104-bit key and a means of distributing keys between users, but in 2001 a fundamental vulnerability was found in it, allowing one to gain full access to the network for a finite (and very short time) regardless of the key length. It is strictly not recommended for use at this time. Therefore, in 2003, a wireless certification program called WPA(Wi-Fi Protected Access), which eliminated the shortcomings of the previous algorithm. Since 2006, all WiFi devices are required to support the new standard WPA2, which differs from WPA by supporting a more modern encryption algorithm AES with a 256-bit key. WPA also introduced a mechanism to protect transmitted data packets from interception and falsification. It is this combination (WPA2/AES) that is now recommended for use in all closed networks.

WPA has two modes for authorizing users on a wireless network - using a RADIUS authorization server (targeted at corporate users and large networks, not covered in this FAQ) and WPA-PSK(Pre Shared Key), which is proposed for use in home networks, as well as in small offices. In this mode, password authorization (from 8 to 64 characters long) is performed on each network node (access point, router or computer emulating their operation; the password itself is pre-set from the access point settings menu or in another way specific to your equipment).

Also, many modern household Wi-Fi devices use the Wi-Fi Protected Setup mode ( WPS), also called Wi-Fi Easy Setup, where client authorization on the access point is carried out using a special button or by entering a pin code unique to the device.

For cases when a fixed set of equipment is used on the network (i.e., for example, a bridge created using two access points or a single laptop connected to the wireless segment of the home network), the most reliable way is to restrict access by MAC address (a unique address for of each Ethernet device, both wired and wireless, in Windows for all network devices these addresses can be read in the Physical Address column after issuing the ipconfig /all command) by entering a list of MAC addresses of “your” devices in the access point menu and selecting access permission to the network only to devices with addresses from this list.

Also, any wireless network has a unique identifier - SSID(service set identifier), which is actually displayed as the network name when viewing the list of available networks, which is set when setting up the access point used (or a device replacing it). When you disable broadcasting (broadcast), the SSID network will appear to users browsing available networks as nameless, and to connect you need to know both the SSID and password (in the case of using WPA-PSK, however, disabling the SSID in itself does not make the network more resistant to unauthorized penetration from outside.

Development of WiFi technology

The main disadvantage of WiFi networks is their low capacity, that is, as the number of clients increases, the connection speed, despite the fact that the signal level is excellent, can greatly decrease. To change this situation, a new standard, 802.11.ax, is currently being developed. Its adoption is scheduled for December 2018. Because of this, there is no exact information about all the features of the new standard yet, and depending on the source, the information may vary significantly, for example, throughput is promised from 1.8 to 10 Gbit/s. From what is known for sure the following can be said:

Operating frequency 2.4 and 5 GHz
. Support for OFDMA modulation coming from LTE/WiMax. Thanks to it, the point is able to transmit data to 30 clients at once (20 MHz channel) or request data transfer from the same 30 clients simultaneously
. Supports 1024-QAM modulation, which will increase data transfer rates

In general, the new 802.11ax standard will provide backward compatibility with previous versions, but full benefits will only be possible if all devices migrate to the new standard. Old adapters will greatly reduce performance.

Mark Abramy

July 2005

The easiest way to organize a small home local network, or to ensure the sharing of an Internet channel by several residents of nearby houses, is Wi-Fi. The main advantage of a wireless connection is that even novice users can easily organize it, and without the involvement of official authorities, which is often required when laying an overhead cable or even to access non-residential premises when pulling cables. However, before spending money on new equipment, you need to make sure that its “range” is enough to connect everyone to the network.

Task

Unfortunately, Wi-Fi technology, due to its poor range, is not yet able to connect computers that are at least somewhat distant from each other if they are not in direct line of sight. A couple of reinforced concrete walls in the signal path are enough to completely shield it, and therefore in a real situation, only users located in nearby houses can be connected into a network if their windows, or more precisely, the antennas of Wi-Fi adapters, look at each other. That is, it is much more difficult to contact a friend living in the next entrance, since you will be separated from him not by two double-glazed windows, but by several main walls. Similarly, you won’t be able to connect with a friend from the house opposite if his windows are not directed in your direction.

Is there a way out of this situation, or in any case should we negotiate with the official authorities to extend the air line, or pull wires, installing access points (hereinafter referred to as APs) on the roofs of houses so that the signal from them is not blocked by anything?

Unfortunately, the most obvious solution - increasing the power of the AP - is not suitable for the average consumer. Although the choice of access points today is huge and on the Internet you can even find quite powerful models - with a power of more than 200 mW (RangeLAN products from Proxim, access points and base stations from Vivato, Senao). However, the whole problem is that officially, without any registration and licensing with the Ministry of Communications, a simple user has the right to use only wireless equipment of very limited power - only up to 100 mW or, according to the designation most often found in the specifications of access points - up to 20 dBm . But even this is just the maximum possible value - in reality, the most common “household” access points from well-known manufacturers have much lower power (for example, 17dBm, that is, half the permitted value), and to find something among them, although To get close to the coveted 20 dBm, you will have to make a lot of effort. “Forbidden” 200 mW is easier to find than “legal” 100 mW!

The second method that comes to mind is the use of powerful highly directional antennas. In this case, all the power emitted by the access point will be directed towards the remote PC and there will be a chance to break through serious obstacles.

Let's try to find out how realistic this is - how far does one access point with a directional antenna “hit” in urban areas? Will it be possible to “break through” reinforced concrete walls in this case?

Test

To evaluate the real “penetrating power” of Wi-Fi, we took several typical access points that support different types of extended 802.11g: TRENDnet TEW-411BRP+, D-Link DWL-2100AP, U.S. Robotics USR805450, as well as D-Link ANT24- directional antennas 1201 (12 dBi) and TRENDnet TEW-OA14DK (14 dBi). It is claimed, for example, that the latter can connect wireless devices at a distance of up to 8 km in line-of-sight conditions. Since in this case we are not testing the access points themselves or even checking the speed of the received channel, but are just trying to find out the “range” of the technology itself, all we need for this rapid evaluation test is to turn on all three APs and walk around the house with a PDA equipped with a Wi-Fi module and a program that displays the radio signal level.

So, stage one is the use of standard antennas. We locate the TD on the fifth floor of a standard five-story panel building and find out that already on the third floor there is practically no reception. That is, inside the house you can reliably connect only PCs located on adjacent floors and no more than two, maximum three reinforced concrete walls from the AP.

We go outside. From the side of the house where the windows of our “test” apartment face, that is, within line of sight, the signal is fairly decent at a distance of about 200 meters, but the stability of reception is no longer the same as at 100 meters. If a house gets in the way of the signal, it completely shields it. That is, it will no longer be possible to contact, for example, an apartment located on the opposite side of a house located 50-70 meters from you. There will be no signal in the courtyard of your own house, on the side opposite the windows of your apartment - these are still the same 2-3 main walls.

Let's now see what connecting a directional antenna will give us. In this case, the house standing in front of your window is very difficult, but it is possible to “break through”! There is a signal, which means that there is at least a fundamental possibility of connecting two apartments in this way, one of which faces not towards the AP, but in the other direction. But, unfortunately, there is no need to talk about tolerable stability of the connection - the point at which signal reception is possible, you have to literally catch it - a step to the left, a step to the right, and the signal is lost. But even if you “feel” for such a point, having ideally oriented both antennas, the level of lost packets will still be too high.

conclusions

Thus, it is quite difficult to organize a network using one household access point with a directional antenna in conditions of indirect visibility. In the simplest case, you will reliably connect only several apartments located in the immediate vicinity of the AP - above you, below you, as well as your closest neighbors on the floor. In this case, a preliminary test on the ground is mandatory - a lot will depend on the location of the AP and the adapters connecting to it, as well as on the specific equipment and the house itself. Perhaps in the most difficult case, installing an additional circular antenna on the AP or using directional antennas on the adapters farthest from it will help.

A friend in a neighboring house can only be connected if his windows look directly at the access point. If someone happens to be on the opposite side of you, then it is perhaps theoretically possible to “get through” to him, for example, if you have two highly directional antennas with a high gain, fairly accurately aimed at each other, but you can only check this by trying do everything in reality. Therefore, in such a situation, it is better to resort to wires, placing the antenna on the roof or extending the “air wire”. This is wireless technology...

Technologies and equipment

What to do if the option of placing antennas on the roof of the house or laying cables is in no way suitable? In this case, you can try to use a complex solution:

• selecting an AP with a power close to the maximum allowed;
• use of an external antenna with a gain of at least 14 dBi, or better yet, even greater;
• correct antenna location.

When choosing a AP, we would advise you to also pay attention to such a moment as the maximum possible speed. The fact is that today’s standard 54 Mbit/s is still not enough to organize a decent network (read about the 802.11g standard, for example, at www.thg.ru/network/20030311/). Therefore, the best option, in our opinion, would be to choose an AP with support for the SuperG mode, which provides a connection at speeds of up to 108 Mbit/s (note that connecting 802.11b clients will slow down the entire network, so it is better to disable 802.11b support altogether). SuperG is supported by equipment based on Atheros chips, they are quite common, used by different brands, and the user gets some freedom of choice when purchasing an adapter. There are, however, other 802.11g extensions on the market, up to 125 Mbit/s (more about advanced modes in the article www.thg.ru/network/20040127/), you can choose them, but they are perhaps a little more involved to a specific manufacturer, and you will have, for example, to purchase exactly the same adapters for each user, even if someone already has a Wi-Fi adapter, but from a different company. Plus, in the new equipment based on Atheros chips, eXtended Range technology has appeared (for a test of various range increasing technologies, see www.thg.ru/network/200505191/), which again plays into our hands.

Do not forget about the sensitivity of the TD - it can vary quite noticeably from model to model, so before making a choice, you will have to dig through a sea of ​​documentation. But in any case, the final decision should be made only based on the results of testing on real terrain, that is, when purchasing equipment, it is necessary to agree on money back, otherwise the money will be spent and communication will not be achieved.

Selecting and positioning the antenna is also not an easy task (note that not all APs allow you to connect an external antenna). The simplest sector antennas have a gain of no more than 13-15 dBi, but if you find a proprietary antenna with a phased array (PAR), you can get 25 dBi, that is, 10 dBi more, but also with a narrower beam.

There are several options for antenna placement. For example, to organize a network in a multi-story building, it is usually recommended to install the antenna outside (for example, in a window or on the roof of the building opposite), and point it at the facade of the building. In this case, all rooms that face the antenna are guaranteed to be within the access zone. Those rooms that are located on the other side of the building and separated from the antenna by two or more reinforced concrete walls may not be included in the access zone. That is, if you are connecting two houses, then you can achieve the greatest coverage if you use two APs located in each house, with antennas aimed at the opposite house. When connecting three houses, the antennas should be placed on the outer ones and “shine” on the one in the center. If you need to connect machines located at large distances from each other within the same house, and there is no opportunity to install APs (or rather, their antennas) on nearby houses, then you will have to splurge on wireless repeaters scattered throughout all the entrances and floors, or fence a rather complex structure of several APs connected by cable. Of course, although these solutions are the most “long-range”, they are also the most expensive and difficult to implement (note that the capacity of APs is limited, so if you want to connect 30 people, then one AP will not be enough), so they are hardly suitable for everyday use . In addition, we again get a dead zone in apartments located behind the antennas.

1. www.thg.ru/network/20030311/
2. www.thg.ru/network/20040127/
3. www.atheros.com/pt/atheros_XR_whitepaper.pdf
4. www.thg.ru/network/200505191/