How many access points do I need? How to estimate the right number of devices for professional networks
How many access points do I need? A common question in professional network deployment. Estimating the number of access points for different environments is crucial: especially in structures with large areas and requiring large numbers of devices, calculating the wrong number can lead to unexpectedly high costs and a feeling of dissatisfaction when buying unnecessary APs. Conversely, when you want to save too much money, you risk underestimating the number of devices and not buying enough access points for your business.
Tanaza has defined the most important factors to consider and how to estimate the number of access points required.
What factors to consider when estimating the number of access points?
- Check floor plan of the environment;
- Identify the types of walls;
- Evaluate the number of contemporary users;
- Calculate the Capacity/Throughput per user/application.
Check floor plan of the environment
The building plan is often a factor that is taken for granted when estimating the number of devices to be purchased. Modern buildings can have different floor plans: L, H, or T.
In this scenario, the geometry of the plan itself influences coverage. In these cases, devices can not be placed in a position that will be central to all users, without the signal crossing several external or internal walls.
Follow this basic networking rules:
- L-shape – estimate more square feet than 2;
- T-shape – estimate more square feet than 3;
- H-shape – multiply the estimated square footage by 4.
Identify the types of walls
Intuitively, concrete, brick, and reinforced concrete walls have a high magnetic permeability index. In this case, the number of devices required for efficient WiFi signal propagation is higher.
Concrete, with or without reinforcement, has a high attenuation level and represents a significant obstacle between the access point and the client device. The loss of decibels of the WiFi signal increases as the frequency increases.
In the table, below you can see the signal losses by frequency and material. The table is based on calculations and experiments carried out by the US National Institute of Standards and Technology.
|Materials||2.4GHz (dBm)||5GHz (dBm)|
For example, using the concrete heavy example in the table above and imagine there is a concrete heavy wall between the AP and the client: at 2.4 GHz, the transmission loss is ~23 dB- meaning that as the signal goes through the wall it is decreasing by that amount of attenuation. Now if the operating frequency is changed to 5 GHz, the transmission loss is going to be higher because the frequency is higher – so in this case it goes to ~45 dB.
Estimating the number of access points, it is fundamental to consider the technical characteristics and configurations of the devices, including bandwidth, signal strength, and range. For networks that require large numbers of devices, a platform like Tanaza is essential for comprehensive remote management. The platform allows the signal status to be monitored 24/7, with the ability to modify the necessary settings for each access point in bulk.
Number of contemporary users
The number of contemporary users is a parameter for estimating access points that should only be considered in areas with a large number of users such as schools, theatres, auditoriums, hotels, universities, and sports centers.
Imagine a traditional football stadium with a capacity of 50000 people for a summer concert. The size of the rectangular area is 650 feet x 750 feet. To obtain the number of access points required, you need to calculate:
TOTAL ENVIRONMENT AREA / MAXIMUM COVERAGE AREA OF THE DEVICE
At this point, we consider the number of connected users. With the stadium at max capacity, let’s assume that only 50% of the spectators have connected to the WiFi network: 25000 spectators. Of these, 10,000 are using it together to share the most exciting moments of the event. Once you have performed the above calculation to determine the number of access points needed, you can divide the number of users / the number of APs to quantify the number of access points per device.
Calculate the Capacity/Throughput per user/application.
Another method to estimate the number of access points needed is to calculate the capacity requirements. We have already talked about this topic in a previous article: click here to read.
For a quick review, consider 4 basic formulas:
- AP Throughput divided by User Throughput = Users per AP
- Users per AP divided by active users = Usable users per AP
- Usable Users per AP divided by Adoption Rate = Service Area/Cell Size
- Capacity divided by service area = AP count
Available statistics include:
- data received and sent by the network in real-time;
- the status of the access points in real-time;
- historical statistics on possible disconnections;
- RAM/CPU load percentage in real-time;
- blocked packets and error rate;
- the number of connected clients and the aggregate upload and download speed.