Why Does My Cellphone Fail to Connect to Remote Outdoor Access Points?
You’ve probably tried before to connect your cellphone or laptop to the wireless network of an outdoor access point which is a few kilometers away, but failed. Why does it fail even though the Wi-Fi signal is strong?
In this article, we’ll help you figure that out.
Compared with mobile terminals, like cellphones and laptops, outdoor access points like TP-Link Pharos devices and Omada outdoor EAPs usually have a much higher transmission power and antenna gain. This means the wireless coverage range of the outdoor access points is much broader than that of mobile terminals.
Mobile terminals can connect to an access point only when they are in each other’s wireless coverage range. As the following figure shows, Cellphone_1 and Cellphone_2 are both within the coverage range of the access point, while the access point is in the coverage range of Cellphone_1 only. As you can guess, only Cellphone_1 can connect to the access point.
Cellphone_2 can receive the Wi-Fi signal of the access point. When it tries to connect to the access point, it will send a connection request to the access point, but the access point cannot receive the request because it is outside of Cellphone_2’s range. As a result, Cellphone_2 fails to connect to the access point even though it is receiving a signal.
Figure 1 Connecting to the Outdoor Access Point
In general, the greatest distance at which mobile terminals can connect to an outdoor access point depends on their own coverage range. Their coverage range varies according to transmission power, antenna gain, and the wireless environment. When deploying outdoor access points to provide Wi-Fi coverage for places like a plaza or farm, in addition to the coverage range of the access points, you should also consider the coverage range of the mobile terminals.
A good artical, it solves my puzzle.
This article is very concerning and it's surprising that someone signed off on it to be published. It either demonstrates that the author knows little about the subject or demonstrates that the company have decided to intentionally deceive their customers and effectively pass the blame on for substandard products.
Take the last paragraph for example: "In general, the greatest distance at which mobile terminals can connect to an outdoor access point depends on their own coverage range." This is not true. It should read: "In general, the greatest distance at which mobile terminals can connect to an outdoor access point depends on the coverage range of the receiver in the outdoor access point." Sure, a mobile device has very limited transmit/receiver power, antenna gain, sensitivity, etc. due to its size and power preservation constraints (which is why that results in such a small radiation pattern when setting up a mobile hot spot,) but a mains-powered outdoor access point is what will determine whether those weak signals from the mobile device are able to be picked up. This is because wireless communication waves don't just have a hard cutoff line like this article alludes to, they just become weaker and/or more distorted over distance.
The author should also develop their knowledge with things like 'link budgets.' So to summarise:
- When a mobile device is communicating with a more powerful access point, the link budget equation uses the access point's antenna gain and sensitivity for one direction, and the access point's transmit power and antenna gain for the other direction.
- When a mobile device is communicating directly with say another mobile device, all these parameters are replaced by the values for those lower-powered mobile devices.