Why is Wi-Fi signal strength so important?

If you primarily connect your devices to Wi-Fi then signal strength is key to having a good experience. Good signal quality is correlated to good performance and weak signals beget poor performance and connection stability.

Imagine two people having a conversation. The quality of the conversation depends on how loudly each person talks and how well they can hear the other party. In essence, this conversation is a two-way transmission of information from A to B and B to A. If person A cannot hear person B then the quality of the conversation will be poor; conversely, if B cannot hear A then the conversation will be equally poor.  

 If A and B are talking in a typical home or office environment, the quality of their conversation will depend on the following:

a) The distance between A and B: the greater the distance, the harder it becomes to hear the other party.

b) The number of physical obstructions: if there are walls and floors between A and B, each successive obstruction will reduce the quality and impede their ability to hear.

c) The level of noise and interference: if there are other conversations happening in the environment A and B are in, it will be harder to filter out the noise and listen for the information relevant to the conversation.

d) How loudly each person talks: if person A can talk loudly at 75 decibels whereas person B can only talk at 65 decibels, A is less likely to hear B when distance/obstructions/interference factored in.  Conversely, B is more likely to hear A however the conversation quality will still be poor.

e) Their hearing sensitivity: if person A has better hearing than person B, they may be able to receive information in poor conversation conditions and attempt to reply back.  The conversation will still not work if person B has poorer hearing and cannot receive the reply.


How does this long analogy relate to Wi-Fi transmissions you ask? Wi-Fi transmissions are electromagnetic waves instead of sound however, they operate on similar principles to the example above.  The key takeaway is there are many factors that can influence the quality of your Wi-Fi connection and in order to achieve the best performance and stability, you'll want to mitigate those factors as much as possible.  Here are the key factors determine received signal and what you can do to maximize signal strength:


1. Distance

Reduce transmission distances where possible.  Wi-Fi signals lose energy over distance and you want the transmission path between the router and client device to be short as possible to maximize performance.


2. Physical obstructions/barriers

Reduce the number of obstructions in the transmission path.  Each physical object (walls/floors/furniture/appliances) that the Wi-Fi signal passes through absorbs part of its energy.  Denser building materials like metal, concrete and brick cause greater signal attenuation compared to RF-transparent materials like wood or drywall.  Gaining line-of-sight to your wireless router or access point and reducing barriers is critical to maintaining a strong signal.


3. RF interference

Interference comes from a variety of RF producing sources, some of which you cannot control for.  The primary sources of interference are Wi-Fi signals coming from your wireless devices and from neighboring homes (this effect is magnified in high density residences like condos or apartments). Secondary sources are typically devices producing electromagnetic radiation such as cordless phones, wireless cameras, microwave ovens, baby monitors, and etc.  You cannot prevent outside RF signals from interfering however, you can control your own RF-producing devices.  Turn off Wi-Fi and RF-producing devices when not in use and do not install your wireless router in close proximity to said devices.


4. Transmit power (Tx)

Routers and Wi-Fi devices can have varying levels of transmit power.  Some are stronger and can transmit 'louder' than others which effectively increases its transmission range.  Transmit power is typically stronger on wireless access points when compared to client devices such as smartphones, laptops, tablets, or streaming devices.  This means transmissions from the access point are stronger and can be 'heard' at greater distances compared to client devices.


5. Receiver Sensitivity (Rx)

A device's ability to 'hear' or receive information is equally important in maintaining a strong and stable Wi-Fi connection.  The lower the receive sensitivity threshold, the better the device is at 'hearing' weaker signals. Conversely, higher thresholds (closer to 0 dBm) mean that the device is less sensitive and requires a stronger signal in order to 'hear' the transmission.  The balance between transmit power and receive sensitivity determines the overall quality of the transmission.



How do these principles relate to actual measured performance?

The speed or throughput of your Wi-Fi connection is directly correlated to the signal strength; stronger signals result in faster link rates (PHY) and better real-life throughput.  As the signal degrades and becomes weaker, the PHY rate decreases and so does actual throughput.  Here's a generalized graph of depicting the relationship between received signal strength (Rx in dBm) and measured throughput (mbps):



We can determine several things from the graph above:

  1. Throughput (actual measured speed) is positively correlated to signal strength where throughput decreases as signal strength declines (further from 30 dBm)
  2. 5 GHz Wi-Fi throughput is more sensitive to changes in signal and performance degrades more quickly when compared to 2.4 GHz Wi-Fi throughput
  3. 2.4 GHz throughput is less sensitive to changes in signal and can still be usable at weaker signal strengths compared to 5 GHz connections
  4. Maximum throughput for 2.4 GHz signals is significantly lower than 5 GHz signals (particularly at very strong signal strengths between -30 dBm and -65 dBm)


There are distinct thresholds for signal quality and the measured signal in dBm can imply a certain level of performance for typical applications or uses.  Stronger signals will allow more intensive applications like video streaming or downloads/uploads to run more smoothly while weaker signals will only be suitable for light tasks where throughput and timely transmission of data is less critical. The recommended signal range for the best possible experience while connected wirelessly is between -30 dBm to -65 dBm.


Source: https://eyesaas.com/wi-fi-signal-strength/





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