“Need a reliable wireless network”

    Point Type AP-105
    Recently, our company began to receive more often not just requests “count me N access points and a controller”, but already - “we need a reliable wireless network in which users can use their own gadgets in their work”. Today we will tell you what we do and what tools we use in such cases.

    Upon receiving such a request, we begin to ask the client questions that help him understand his task. Summarizing the results, we made a list of the main criteria that a “good” and reliable wireless network should meet:
    1. providing high speed on the radio channel;
    2. coverage of a given space;
    3. the possibility of simultaneous work of the N-th number of customers;
    4. the ability to create guest access and a working network with various levels of security using only the controller’s functionality;
    5. the ability to filter traffic, assign policies and ensure wireless security using the controller;
    6. simplicity of setting up this solution, i.e. on their own without the involvement of third-party specialists;
    7. the possibility of obtaining a guarantee of performance - a test, or a demonstration, and preferably in the field;
    8. Of course, an interesting price.

    As part of this post, we dwell on the first three points. The choice of equipment, the amount of equipment and its location directly affects the reliability of the wireless network at the physical level. That is why we recommend that you conduct the network design phase before implementing the project.

    We partially wrote about the remaining points in the previous post and, most likely, we will still write in the following.

    Real customer task


    Objective: to organize a wireless network in an office consisting of 6 rooms located on one side of the building and on the same floor.

    In stock: layout of rooms, most likely taken from the fire evacuation plan. Red ticks mark target areas.

    The task of a real client is to organize a wireless network in the office

    There is a lot of software for calculating the coverage area, but we prefer to use the original program developed by Aruba Networks - VisualRF Plan. Aruba is now the most technologically advanced developer of Wi-Fi solutions (in our opinion and Gartner's opinion).

    This program is available for download from the vendor's website if you have an account. There is also an online version based on Google maps for designing a network coverage of a street / outdoor area.

    We load this plan into the program with the indication of scale and begin to mark the location and type of walls on it with the mouse. Four wall options are available in this program:
    • Concrete - from concrete;
    • Cubicle - “cubicles”, office partitions;
    • Drywall - from drywall;
    • Glass - made of glass.

    We load this plan into the program with the indication of scale and begin to mark the location and type of walls on it with the mouse.

    In our case, concrete walls are red, yellow plasterboard, which corresponds to the realities of our premises. We mark the area that needs to be covered with a wireless network (gray in the diagram).

    Aruba Planning

    We select the area for planning and launch a dialog box in which you need to set the parameters of the access points and the distribution of subscribers between them (maximum number of users, speed and number of users per channel).

    In our case, we assign:
    • Minimum speed 90Mbps per user;
    • Only 40 users, but no more than 5 per channel;
    • We set the power of the transmitters average so as not to jam the neighboring offices;
    • We define the parameters of the space (environment): we expose the office-gyro;
    • The type of point is defined as AP-105 for the ability to support clients operating at a frequency of 5 GHz (where, by the way, the radio is less loaded).

    Parameters of operation of access points and the distribution of subscribers between them

    Access points Aruba Networks


    Here you need to make a small digression about Aruba access points . Now in the Aruba lineup there is a large line of access points:

    "Standard" access points:

    AP-68 - one radio module, the frequency range is only 2.4 GHz, the aggregate speed is up to 150 Mbit / s, it is intended for rooms with a low density of subscribers.
    AR-93H - one radio module, 2x2 MIMO technology, can operate in the 2.4 GHz or 5 GHz band, aggregate speed up to 300 Mbit / s, has 4 Ethernet ports, allows you to develop cable infrastructure.
    AR-93 - one radio module, 2x2 MIMO technology, can operate in the 2.4 GHz or 5 GHz band, aggregate speed up to 300 Mbit / s, perfect for offices and rooms with low density.
    AP-105- two radio modules, 2x2 MIMO technology, supports simultaneous operation on the 2.4 GHz and 5 GHz bands, allows you to organize a wireless network in rooms where customers with various types of radio modules are concentrated.
    AR-135 - two radio modules, 3x3 MIMO technology, contains two 10/100 / 1000BASE-T ports, aggregate speed up to 450 Mbps, provides high performance and speed even in poor radio conditions.

    Access points for organizing a remote workstation

    Very good when, for example, an employee is on a business trip.

    RAP-2WG - works only in 2.4-GHz with a maximum speed of 54 Mbps, the size of a pack of cigarettes - perfect for taking with you on the go.
    RAP-3WN - one radio module, 2x2 MIMO technology, works in the 2.4 GHz band, supports Instant mode, has a USB port - allows you to connect a 3G / 4G modem, suitable for organizing a remote office.
    RAP-5WN - one radio module, 3x3 MIMO technology, can operate in the 2.4 GHz or 5 GHz band, aggregate speed up to 300 Mbit / s, has 4 copper ports and a USB port - allows you to connect a 3G / 4G modem.
    RAP-100 Series- two radio modules, 2x2 MIMO technology, supports simultaneous operation on the 2.4 GHz and 5 GHz bands, it is possible to connect an external antenna, there is a USB port - it allows you to connect a 3G / 4G modem.

    The following algorithm can help determine the type of access points:

    Algorithm for determining access points

    I note that now, according to statistical information, the percentage of devices that support operation at 2.4 GHz is much larger than the percentage of devices operating at 5 GHz. According to some reports, the ratio is approximately 67% to 33%. It is logical that it makes sense to choose dual-channel access points in the event that you have or plan to appear compatible devices.

    The need for an external antenna can be determined by the specific geometry of the room when, for example, it is necessary to direct the signal into a narrow long corridor. In some cases, the choice between an internal or external antenna can be a matter of the client’s taste.

    Option No. 1: AP-105 at medium power


    Let's go back to this picture:

    Parameters of operation of access points and the distribution of subscribers between them

    Select the type of point AP-105 and click the "OK" button. Based on the given parameters, we get the following picture:

    Reliable wireless network

    The resulting circuit reflects the radio frequency coverage of a given area, on which the colored areas correspond to the following values:
    • Red - signal level: -45db;
    • Orange - signal level: -55db;
    • Light green: -65db, etc.

    When you are in the above three areas, you can work comfortably. To implement this, the program proposed the installation of four access points.

    Option number 2: AP-135 to the maximum


    Consider an alternative with a more powerful top-end AP-135 access point and maximum power (30 dbm):
    • 40 users, a maximum of 10 per channel;
    • minimum speed 90Mbps;
    • each transmitter power set to maximum;
    • access point select AP-135 (high user density).

    We

    Option with a powerful top-end AP-135 access point and maximum power

    get : We see that two AP-135 access points at maximum power should cope with the task no worse than four AP-105 at average power. However, there is a nuance.

    Conclusions and Results


    There are various ways to design a future wireless network - different manufacturers, different models, different numbers of points, etc. Software tools help in a convenient way to evaluate various options and make an argumented choice in favor of one of them. However, there are nuances that also need to be considered.

    Firstly, the price of the AP-135 is one and a half times higher in comparison with the AP-105 and, acquiring two top access points, instead of four younger, the cost gain will be less than half: 1.5x * 2 = 3x against 4x.

    Secondly, setting the maximum transmitter power on the access point in some cases may not solve the problem of attenuation. Given that there is still a transmitter on the end device, which should also “penetrate” all obstacles.

    If you have rooms on different floors, then the points set to the maximum will jam each other - as you know in the 2.4 range there are only 3 disjoint channels. Even if your office is located on only one floor, then you will begin to "jam" the neighbors.

    In this article, we gave a real example of calculating a project to provide an office with a wireless network. The next step we usually offer, the customer agrees, and we conduct a field test of the selected equipment in its territory. For these purposes , the Aruba Networks demo fund has been formed in our Competence Center .

    Successful and reliable operation of your Wi-Fi!

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