The constraints on a WiFi deployment project are incredibly numerous. A necessary phase for any project is to define the need to size the solution clearly. “The customer is king” This adage works particularly well in WiFi since the quality of the connection and a significant number of decisions are made directly by the customer’s WiFi equipment and not by the infrastructure and WiFi terminals.
What is the number of clients to support? What is the estimated density per coverage area? What is the inventory of customer types, PC/phone/tablet brands? Is there any specific equipment? Should we carry out special tests on industrial equipment to check their ability to connect? These questions have a strong relationship with radio capacity but also with the ability to implement security at the level of client equipment.
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Customer Uses
Each area to be covered must be identified with the actual uses of customers connecting to the network: office, hotspot, telephone, video, and geolocation. It is necessary to question the load peaks in specific areas: should all equipment be able to make IP calls in the canteen during the lunch break? Is Internet access provided for all equipment if the 500-person arena is filled with journalists for the events? Finally, an important question: should a person be able to make IP calls and move around the premises simultaneously? (roaming problem). Analyze constraints
The constraints on a WiFi deployment project are incredibly numerous and can be divided into four categories.
Physical Environmental Constraints
A site visit or knowledge of the areas to be covered is strongly recommended to evaluate the first criteria to be taken into account. How high is the ceiling? If the terminals must be hidden in the false ceiling, what is the material of this false ceiling? Can the terminals be installed anywhere on the false ceiling? What are the types of wall/partition materials? For warehouses, which direction are the aisles? What are in the warehouse racks (metallic and liquid objects will tend to absorb radio waves greatly significantly)? Outdoors, what is the position of the trees?
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Physical Connection Constraints
First of all, the golden rule to note for a classic omnidirectional WiFi terminal with integrated antennas is the following: “A terminal must always be installed horizontally”. Indeed, we must imagine the radio propagation from this type of terminal in the form of a “doughnut”. If the terminal is installed vertically, it is mainly the floor and the ceiling that will be best served and less the surrounding areas. Beyond the direction of installation of the terminal, two other constraints of connecting WiFi terminals must be taken into account:
Electrical
Like all electronic equipment, a WiFi terminal needs a power supply between 15W and 45W for most models, depending on the functionalities activated. Either it is possible to obtain a low current outlet at each WiFi terminal location, in which case the direct connection solution can be chosen.
The same goes for the “Power Injector” solution, which allows the RJ45 cable coming from the access switch to be taken as input and the electrical inlet to offer a simple RJ45 cable operating in PoE (Power over) as an output. Ethernet). In the majority of installations, we will prefer to provide switches capable of sending energy directly to the ports concerned via PoE towards the WiFi terminals. Note that current WiFi terminals mainly operate in PoE+ at 30 Watts (802.3at standard).
Network
Two possibilities for network connection of WiFi terminals. The most used solution is, of course, the RJ45 wired connection, for which we will pay attention to the maximum distance of copper transmissions, which is 100 meters, but also to the top speed allowed by our network infrastructure. Indeed, today’s WiFi standards make it possible to go up to a theoretical speed of 7 Gbps on radio communication (and therefore seven times more than a classic category 5E copper Ethernet cable at 1Gbps), so be careful of the bottlenecks of throttling on the rest of the network for the high-speed needs expressed by customers.
Another possibility of connecting to the network for areas that could not be wired with RJ45: Mesh architecture. This architecture allows WiFi terminals to set up a radio “backhaul” with another terminal itself connected to the network, thus constituting the “uplink” to the rest of the network.
External Radio Constraints
The radio constraints to be taken into account first are the interferences that come into play in the areas to be covered. Other neighboring and uncontrolled WiFi networks, for example, can constitute the first source of interference. Also to take into account: the famous microwaves, of course, which emit several hundred Watts at 2.4 GHz, specific models of motion detectors, all Bluetooth devices, DECT cordless telephones, lighting systems using neon gas, etc., to name only the main ones.
Another type of external radio constraint, and not the least, is the clients to be connected to our network. Do known equipment have frequency band limitations? Do they have capacity limitations on the channels to use? Are we aware of any recurring problems with these types of clients (such as roaming and hidden SSID issues for Chromebooks, for example, or Sticky Client for equipment with old drivers)?
Internal Radio Constraints
Finally, we may come up against radio constraints inherent to the installation of a WiFi network.
These constraints mainly consist of the design of the channels to avoid interference between radio cells (CCI: co-channel interference) and power limitations to establish good communication with clients (the cells must not be too large by part, but we must also remember that the client equipment does not have the same power capacities as a WiFi terminal, we must avoid imbalances) as well as to comply with the legislation of the country concerned (20 dBm in 2.4 GHz and 23 dBm at 5 GHz in France for indoor environments).
Carry Out A Preliminary Audit
Once all the needs and constraints have been listed, it is essential not to rush into deployment but to carry out a study and audit phase of the areas to be covered. To do this, two main tools dominate the market for experts in these subjects: the Ekahau tool and the AirMagnet suite. Depending on the environment of the areas to be covered and the project resources, two types of audits can be carried out.
Plan Audit
Equipped with plans of the areas to be covered, it is possible to position the types of walls to be taken into account, as well as the characteristics of the terminals that will be installed, to generate a simulation of the optimal position of each of them. It is then possible to calculate the potential coverage areas and a proposed configuration of the powers and channels of our terminals. To go further, we can add a notion of capacity planning to the simulation to anticipate the type and number of customer equipment in the different zones and deduce a better approximation of the quantity and position of the terminals.
On-Site Audit
In addition to the on-plan audit, it is strongly recommended to physically go to the premises to be covered to evaluate (with the tools mentioned) the actual existing interferences and the types of walls with their attenuation. These measures constitute what is called a “passive” audit. It is possible to consider an active audit by bringing a WiFi terminal of the same model as that which will be deployed, mounting it on a mast to simulate its installation on the ceiling, and measuring the quality of the connection and the actual flow rate of a customer in the environment of the area to be covered. Active audits provide an accurate measurement of environmental conditions and are preferred.
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