Friends, this article is a continuation a series of articles on how to improve WiFi performance in an office or enterprise.
Expectations and surprises
Let's start with some facts.
The strength of the Wi-Fi signal at the receiving point depends on several factors:
- distance (from the client to the access point);
- antenna gain;
- radiation pattern;
- the presence of external interference (including from devices with Bluetooth, microwave ovens, and so on);
- obstacles in the signal path.
Therefore, if there is a change in the landscape, the appearance of “foreign” signal sources, the installation of additional insulating partitions, and so on, you have to adapt to new conditions.
Important! It is impossible to speculatively determine all the nuances that affect the quality of a wireless network. In order to develop more or less accurate data in each specific case, it is necessary to conduct a preliminary study.
Much depends on the client devices. One of the interesting examples is the case when the internal IT infrastructure was designed quite a long time ago and was fully adapted to the 2.4 GHz band. However, the massive popularity of 5 GHz devices has made its own adjustments. It required a partial replacement of wireless equipment and a change in the access point placement map, taking into account recommendations to place clients in the “line of sight zone”.
To clarify certain preliminary decisions, a detailed mapping terrain (examination and mapping of Wi-Fi signal coverage areas from all access points).
Sometimes, at the initial stage, you have to be content with only knowing the approximate number of devices and an approximate layout, and clarify the questions that arise after installation, followed by testing and debugging on site. This also applies to the choice of antennas for signal amplification.
The situation with the design and modernization of Wi-Fi is somewhat reminiscent of disease prevention. Of course, no one has an accurate prediction of what diseases will fall ill in the near future. However, knowing the general principles, such as observing the rules of hygiene, maintaining a healthy lifestyle, and following the recommendations of doctors, many troubles can be avoided.
In the same way, when designing various systems, you cannot know everything in advance, but there are some general principles that our article is devoted to.
An additional antenna, repeater, or point-to-point data transmission?
There are several ways to improve your network experience. Accordingly, there are several types of equipment that help to do this.
Additional antenna
Additional external antennas are used to amplify the signal of access points. Sometimes, in addition to the antenna itself, an amplifier is included in the kit. Such devices are often externally powered, such as from a wall outlet.
The main merit of the antenna is that it simply increases the signal strength.
This approach is good when there is a large area with a small number of customers. For example, an industrial warehouse. By placing the antenna from a single point under the ceiling in the center of the room, you can get accessibility throughout the area for several storekeepers and warehouse visitors.
If you put two such powerful emitters side by side, then instead of helping each other, they will introduce mutual interference.
It should be remembered that no matter how powerful the antenna is, the number of connected clients will be limited by the internal resources of one access point.
For a busy office "anthill", when most of the consumers are next to each other, building a network based on a single access point, even with the most powerful antenna, is not a good idea. More power is not so in demand here, it will be much more useful to balance the load between several points, the ability to accept a larger number of simultaneous requests from clients or block unwanted access.
Therefore, we leave the access point with an external antenna in its place - in splendid isolation under the roof of the warehouse and move on to another point in our description.
Using repeaters
A signal repeater is a device that receives a signal from an access point and sends it to the client, or vice versa - from the client to the point.
This allows you to expand the coverage of your wireless network. Clients will be able to connect to the repeater in rooms where the signal begins to weaken without any problems.
The disadvantage of this type of device is the need for the repeater not only to communicate with the client, but also to interact with the main access point. If only one radio module is used, respectively, and it has to work "for two", which reduces the speed of access over the network. This variant is usually found in inexpensive devices for home use.
For situations where speed drop is unacceptable, it is recommended to use repeater models with two radio modules. The presence of a second Wi-Fi receiver-transmitter provides a more stable and faster wireless network.
Another fact to take into account is the ability to work in both bands: 2,4 GHz and 5 GHz. Some older or very basic home-only models only support the 2,4 GHz band.
Council. If you decide to use repeaters, then you should consider the model - dual-band wireless network repeater.
Using a Wireless Signal to Link Multiple Access Points
This option is used when it is not possible to connect all access points to a single network using a cable infrastructure. This is somewhat reminiscent of using repeaters, but instead of a “stupid” repeater, a full-fledged access point is used.
As in the case of the repeater, it is strongly recommended to use access points with two Wi-Fi interfaces. One of them will be used to communicate with a neighboring point, and the second one will provide interaction with clients.
If a point with one interface works in this mode (to do this, you need to configure the interface in AP + Bridge mode), the final data transfer rate between the client and Wi-Fi network resources will be significantly lower.
This dependence is due to the fact that Wi-Fi technology uses time division multiplexing (TDM), and data transmission at one time is possible only from one network member in one direction.
Unfortunately, working in this mode does not provide distribution between multiple access points. As already mentioned in the article - a situation arises when a large number of users are connected to remote access, and nearby access points are practically not loaded.
The most preferred option is to use the connection of access points via a network cable with synchronization through a special Wi-Fi network controller.
On the wall or on the ceiling?
There are various options for placing access points. Depending on the convenience, the specifics of the premises: a large office, a small office, a restaurant, a shop, and so on, you have to select the most suitable accommodation option. In some cases, it is more convenient to place the access point on the wall, in some - under the ceiling or even under the roof itself. A separate case is access points for outdoor placement, in other words, “on the street”, but at the moment we will only touch on indoor equipment.
Placing an access point on a wall has its own difficulties. You may need to drill walls for fixing, solve issues with power supply and network cables, and so on.
But what if you place the access point not on the wall, but immediately under the ceiling? What difficulties await here?
First of all, there may be problems with fixing the point to the ceiling. For example, in modern offices, a false ceiling is made of plasterboard, which makes its own adjustments to the process of placing equipment.
Therefore, you need to immediately think about the mounting option.
If it is planned to connect access points to the network via cables, it may be necessary to additionally carry out special gutters above the false ceiling, in which power cables and LAN communications will be laid.
If there is no false ceiling at all, then the issue of drilling ceilings and connecting power and network cables to the access point may not be the easiest thing to do.
Recently, loft-style offices have become widespread, in which there is no concept of a ceiling at all, and all kinds of pipes and communications pass over the heads of employees. In such a situation, it will fix the access point and it will be much easier to run cables to it. However, the presence of large metal objects, such as thick pipes, fittings, gratings - all this can change the conditions for the signal to pass through. Let me remind you that the final answer to the applicability of a particular scheme can only be given by a special study or specific practical experience.
The figure shows option 1 with ceiling placement. With this placement, access points can influence each other. And here you will need standard methods for reducing mutual interference: using different channels and adjusting the power described in the article “Improving Wi-Fi performance. General principles and useful things ".
Figure 1. Placement of access points under the ceiling.
However, ceiling placement can provide better coverage for the entire office space.
Direction of emitted signal
After weighing all the advantages of one or another option, you should not rush to just hang the access point from the wall to the ceiling, or vice versa, from the ceiling to the wall. To begin with, it is worth solving the issue of changing the direction of the signal.
For wireless network equipment, originally designed to be placed on the ceiling, the signal propagates in radial circles, the center of which is the transmit-receive module (see Figure 2).
Figure 2. Signal propagation for wall and ceiling placement.
What happens if you take an access point for ceiling placement and just hang it on the wall? In this case, the signal will be well available only in the immediate vicinity. For clients on the opposite side of the room, the signal strength will be significantly lower and the connection will not be very good.
A similar problem occurs when a wall-mounted access point is placed on the ceiling. Its radiation pattern is directed not round, but from the wall on which the dot hangs - along the room (see Figure 2). If such a point is on the ceiling, then the main coverage area will be directly below it. Simply put, the radio module of this point will "shoot at the floor", from top to bottom.
As mentioned above, in some cases it is not so easy to immediately select the optimal location for all access points. Fortunately, Zyxel has versatile models that allow you to choose the mode of use depending on the placement: on the ceiling or on the wall.
Note. We recommend paying attention to models that are adapted for two mounting options, and also have two radio modules, for example, .
It is also worth thinking about the versatility of placement if you plan to move the office. In this case, it would be wise to choose adaptable access points.
Let's summarize briefly
There are no “one-size-fits-all” methods, but following some recommendations allows you to avoid many problems in designing, deploying and maintaining a Wi-Fi network.
Transmitting devices should not be placed too close to each other.
In some cases, it is better to use access points to be placed on the ceiling, in others - on the wall. It is necessary to take into account the radiation pattern for each of the options. There are universal access points with the ability to switch the usage mode.
In the next article in this series, we will talk in more detail about the placement of wireless equipment.
Questions on the choice of equipment, advice on setting up and configuration, exchange of opinions? We invite you to our .
Sources of
Source: habr.com