Wi-Fi is a technology that allows devices to connect to the internet wirelessly using radio waves. It works by using a wireless router or access point, which sends and receives data over the air using a series of antennas.

When you want to connect to the internet using Wi-Fi, you first need to be in range of a access point. These devices transmit a signal using a specific frequency range, usually in the 2.4 GHz or 5 GHz bands.

An AP acts as a hub, meaning only one device can communicate at a time. An AP uses a technology called carrier sense multiple access with collision avoidance (CSMA/CA) to manage communication with multiple devices at a time. This technology allows the AP to detect when other devices are using the wireless frequency and to avoid transmitting at the same time. 

Electromagnetic waves, such as radio waves, are characterized by their frequency. Different frequencies of electromagnetic waves have different properties and can be used for different purposes. For example, radio waves with a low frequency (535Khz – 1605kHz) such as those used for AM radio, can travel long distances, and can penetrate solid objects, but they are not very efficient at carrying data. On the other hand, radio waves with a high frequency, such as those used for Wi-Fi, can carry a large amount of data, but they do not travel as far and are more susceptible to interference.

The WiFi Alliance has done a tremendous job to standardize and develop the wireless standards that we have come to love rely heavily on today.  The develop and standardize the wireless frequency and channels used to ensure we don't have vendor interoperability issues. There are 3 primary frequency that are used today, going oldest to newest:

2.4 GHz: This is the most common frequency band used for Wi-Fi. It is used by many different types of devices, including laptops, smartphones, tablets, and smart home devices. The 2.4 GHz band is relatively crowded and is prone to interference from other devices, such as Bluetooth devices and microwaves. Disable when possible. 

5 GHz: This frequency band is used by some Wi-Fi devices and is generally less crowded than the 2.4 GHz band. It is typically used by devices that require a higher data rate, such as gaming consoles and streaming devices. The 5 GHz band is more susceptible to interference from physical barriers, such as walls and floors, which can affect the range and performance of the Wi-Fi connection.

6 GHz: This is a newer frequency band, standardized in Q3 of 2021, is currently being made available for use by Wi-Fi networks and soon Bluetooth. It is expected to be used by the next generation of Wi-Fi devices, known as Wi-Fi 6e. The 6 GHz band is much larger than the 2.4 GHz and 5 GHz bands and is expected to support a larger number of devices and higher data rates. The higher data rates are more import but due to the higher frequency of 6GHz, it’s the most susceptible to interference out of the 3. Most devices currently do not support this frequency, but it will be the primary go to frequency in the future

Wi-Fi networks, channels are used to separate different networks, you can think of a channel a a specific range within the frequency. Its important to ensure that each access point is assigned to a different channel to prevent interference between them. Different Wi-Fi standards use different numbers of channels and different frequency bands.

Overall, channels are an important part of wireless communication and are used to separate different networks and prevent interference between them. They allow devices to transmit and receive data over the air using specific frequency bands.

Channel separation is important because it helps to prevent interference between different networks. Interference can occur when two or more devices transmit data over the same frequency band at the same time, resulting in the signals becoming mixed and difficult to distinguish. This can cause problems such as reduced data rates, dropped connections, and poor communication quality.

A common term you may run into when troubleshooting wireless is SNR. SNR stands for Signal-to-Noise Ratio. In the context of wireless communication, SNR is a measure of the strength of the signal relative to the level of background noise on the channel. It is a ratio of the power of the signal to the power of the noise, and is typically expressed in decibels (dB). Its very common to see an access point using anywhere from 9dbm to 30dbm indoors. Its very important to have a good wireless design or to statically assign transmit power to prevent connectivity issues, MORE POWER IS NOT BETTER.

SNR is an important factor in wireless communication because it determines the ability of a receiver to accurately detect and decode the signal. In general, a higher SNR is desirable because it allows the receiver to better distinguish the signal from the noise, which can improve the reliability of the communication.

So how do you calculate good SNR? Lets say your received signal strength from the nearest access point is -67 (Great connection) and your secondary RSS is -92 (Unusable). The difference between the 2 values is SNR, in this example it would be -25 which is very good! Its recommend to have a -25 SNR for VoIP, but very hard to obtain.

In general, a signal strength of -65 dBm or higher is considered to be good for a wireless voice call. This is because a signal strength of -65 dBm or higher is typically sufficient to provide reliable communication without experiencing dropped calls or significant delays. While in reality this isn’t always achievable, but anything worse than -72 you’ll likely run into connection issues for your most important video call. Low data transfers are achievable with a -80 connection but the quality of the RF frequency will be the final determine of how well things work after like we previously talked about in the SNR section.

RSS stands for Received Signal Strength, and it is a measure of the strength of a wireless signal as it is received at a particular location. In general, RSS is expressed in decibels (dB) and is a negative value. RSS is typically a negative value is because it is measured relative to a reference value. In the case of wireless communication, the reference value is typically the power of a reference signal, which is defined as 0 dBm. The power of the reference signal is the power of the signal as it is received at a distance of 1 meter from the transmitter. We will not touch on how different access points and antennas effect coverage patters or how different antenna require more power.

If I had a dollar for every time I heard this I'd be a millionaire,  once the wireless is complete deployed its likely never the access point or the WLC at fault. I'm going to list out quickly the most common issues we run into if SNR and RSS is not the issue. I'm going to break it down into 2 primary categories. Always start by asking the question of who is this effecting, If its a large portion of the network the issues most likley resides on DHCP, DNS or a hardware failure.

Not able to connect to the Wifi

1. • Incorrect login credentials - If you are trying to connect to a secured network or service, you may need to enter a username and password. If you enter the wrong login information, you will not be able to connect.

   • Network congestion - If too many devices are connected to the same access point, common in stadiums, which prevents anyone from getting connected

   • Outdated software or firmware - If you are using outdated software or firmware on your device, it may not be compatible with the network or service you are trying to connect to. Check to ensure you are running the newest drivers on you device.

   • Hardware issues - If your device's hardware is damaged or not functioning properly, it can cause problems with connectivity.

   • Incorrect Certificate - Its very common to require a certificate to connect to WPA2-Enterprise and WPA3-Enterprise. Verify the proper certificate is installed on the device, as check the expiration date as they are commonly renewed yearly. 

Able to connect to the WiFi but nothing works

1. • DHCP - Common issues we run into is running out of available IP address to be handed out to client devices or the DHCP server may be completed unresponsive. Check your device to see if you have gotten an IP address. This may only cause issue for new users that are connecting. Also ensure there isn't a static IP assigned to the device. 

   • Default Gateway - Lets say you've got an IP address but still nothing works, the next common issues is that the defaullt gateway isn't reachable. If its only effecting one person, its likely a VLAN tagging issue. If the wireless is down for everyone resolve the default gateway reachability issues.

   • DNS - The culprit that loves to bring down the internet. if you can ping the internet ( example 8.8.8.8 ) but you can't load any webpages its DNS.