Improving the work of Wi-Fi. Part 2. Equipment Features

    Friends, this article is a continuation of the first part of a series of articles on how to improve the work of WiFi in the office or in the enterprise.

    Expectations and surprises

    As an introduction, here are some facts.

    The power of the Wi-Fi signal at the point of reception depends on several circumstances:

    • distance (from client to 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 of landscape, the appearance of "alien" 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 the wireless network. In order to produce more or less accurate data in each particular case, a preliminary study is necessary.

    Much depends on client devices. As one of the interesting examples, one can cite the case when the internal IT infrastructure was designed long ago and was fully adapted for the 2.4 GHz band. However, the massive popularity of 5 GHz devices has made adjustments. A partial replacement of wireless equipment and a change in the location map of access points were required, taking into account the recommendations to place customers in the “line of sight”.

    To clarify certain preliminary decisions, a detailed mapping of the terrain helps (examination and mapping of the coverage areas of the Wi-Fi signal from all access points).

    Sometimes at the initial stage you have to be content only with knowledge of the approximate number of devices and an approximate layout, and clarify emerging issues after installation, followed by testing and debugging in place. This also applies to the selection 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 to become ill in the near future. However, knowing the general principles, such as following 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, one cannot know everything in advance, but there are certain general principles to which our article is devoted.

    An additional antenna, repeater or data transfer between points?

    There are several ways to improve network performance. Accordingly, there are several types of equipment that helps to do this.

    Additional antenna

    Additional external antennas are used to amplify the signal of access points. Sometimes an amplifier is included in addition to the antenna itself. Such devices often have external power, for example, from a wall outlet.

    The main merit of the antenna is that it simply increases the signal power.

    This approach is good when there is an extensive space in which there is a small number of customers. For example, an industrial warehouse. By placing the antenna from one single point under the ceiling in the center of the room, you can get accessibility over the entire 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 "ant hill", when most consumers are next to each other, building a network on the basis of a single access point even with the most powerful antenna is not a good idea. Great power is not so demanded here, load balancing between several points, the ability to accept a greater number of simultaneous requests from clients or block unwanted access will be much more useful.

    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 repeater is a device that receives a signal from an access point and sends it to a client, or vice versa, from a client to a point.

    This allows you to expand your wireless coverage. Customers 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, he has to work “for two.”, Which reduces the speed of access over the network. This option is commonly found in low-cost devices for home use.

    For situations where the speed drop is unacceptable, it is recommended to use models of repeaters with two radio modules. The presence of a second Wi-Fi receiver-transmitter provides a more stable and faster wireless network.

    Another fact that needs to be taken into account is the ability to work in both bands: 2.4 GHz and 5 GHz. Some outdated or very simple models for home use only support one band - 2.4 GHz.

    Tip . If you decide to use repeaters, then it is worth considering the AC1300 MU-MIMO model - a dual-band repeater of a wireless network.

    Using a wireless signal to connect multiple access points

    This option is used when it is not possible to connect all access points to a single network using cable infrastructure. This is somewhat reminiscent of the use of repeaters, but instead of a "dumb" repeater, a full-fledged access point is used.

    As with the repeater, it is strongly recommended that you use access points with two Wi-Fi interfaces. One of them will be used to communicate with a neighboring point, and the second - to provide interaction with customers.

    If a point with one interface works in this mode (for 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 moment in time is possible only from one network participant in one direction.

    Unfortunately, working in this mode does not provide distribution between several access points. As already mentioned in the article “Synchronization of Wi-Fi access points for collaboration” , a situation arises when a large number of users are connected to the remote access and the access points located nearby are practically not loaded.

    The most preferable 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 room: a large office, a small office, a restaurant, a store, and so on - you have to choose the most suitable accommodation option. In some cases, the access point is more convenient to place on the wall, in some - under the ceiling or even under the roof itself. A separate case is access points for outdoor use, in other words, “on the street”, but at the moment we will only deal with equipment for indoor use.

    Placing an access point on a wall is your difficulty. You may need to drill walls to fix, solve problems with power 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, problems with fixing the point to the ceiling are possible. For example, modern offices make false ceilings from plasterboard plates, which makes adjustments to the equipment placement process.

    Therefore, you need to immediately think about the mounting option.

    If you intend to connect access points to the network via cables, you may need to additionally conduct special gutters above the false ceiling, in which power cables and LAN communications will be laid.

    If there is no false ceiling, the issue of drilling ceiling ceilings and bringing power and network cables to the access point may not be the easiest thing.

    Recently, offices in the "loft" style are widespread, in which the concept of a ceiling is generally absent, and all kinds of pipes and communications pass over the heads of employees. In such a situation, it will fix the access point and conduct cables to it will be much easier. However, the presence of large metal objects such as thick pipes, fittings, gratings - all this can change the conditions for the passage of a signal. 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 arrangement, access points can influence each other. And here you will need standard methods to reduce mutual interference: the use of various channels and power adjustment, described in the article “Improving Wi-Fi. General principles and useful things . "


    Figure 1. Placement of access points under the ceiling.

    However, ceiling placement can provide better coverage of the entire office space.

    Direction of emitted signal

    After weighing all the advantages of this or that option, do not rush to just outweigh the access point from wall to ceiling, or vice versa, from the ceiling to the wall. To begin with, it is worth solving the problem of changing the direction of the signal.

    For equipment for a wireless network, originally intended to be installed on the ceiling, the signal is propagated by radial circles, the center of which is the transmitter-receiver module (see Figure 2).


    Figure 2. Signal propagation for wall and ceiling placement.

    What happens if you take the access point for ceiling placement and just hang it on the wall? In this case, the signal will be well accessible only in the immediate vicinity. For customers on the opposite side of the room, the signal level will be significantly lower and the connection will be not very high quality.

    A similar problem occurs if the wall-mounted access point is placed on the ceiling. The radiation pattern in it is directed not round, but from the wall on which the dot hangs - along the room (see Figure 2). If such a point appears 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, NWA1123-AC PRO .

    The versatility of accommodation is also worth considering if you plan to move the office. In this case, it will be wise to choose adaptive access points.

    To summarize briefly

    There are no “for all occasions” methods, however, following some recommendations avoids many of the problems of designing, deploying, and maintaining a Wi-Fi network.

    Transmitters should not be placed too close to each other.

    In some cases, it is better to use access points for placement on the ceiling, in others - on the wall. You must consider the radiation pattern for each of the options. There are universal access points with the ability to switch the use mode.

    In the next article from this series we will talk in more detail about the issues of placing wireless equipment.

    Questions on the choice of equipment, advice on configuration and configuration, exchange of views? We invite you to our telegram .


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