Expanded WiFi coverage with a Rasp Pi access point network

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Beacons

A network of access points consisting of several Raspberry Pi computers provides an economical way to establish reliable WiFi access, even in difficult-to-reach areas. The resulting coverage is good enough that you can freely roam, even with latency-sensitive applications like video chat.

Frequently, the private place you have found for conducting a video chat via a mobile device does not provide a high enough WiFi data transmission rate for smooth and consistent transmission. This problem can arise in multistory apartment buildings with reinforced floors or in a remote corner of your yard. Reception issues are caused either by insufficient signal strength or getting tangled in the channel underbrush of neighboring WiFi networks whose access points unfortunately use channels that overlap that of your network.

Data Rates

The WiFi standard currently most often used is IEEE 802.11g, and it is the basis of the discussion in this article. This standard specifies a data rate of 54Mbps when fully utilizing 20MHz channel spacing. In practice, an actual effective data rate of only about 22Mbps can be obtained, even under ideal conditions.

This effective data rate is further reduced if neighboring WiFi cells either completely or partially (in 5MHz segments) overlap with the channel area of your own access point. If the reception quality at either endpoint of the wireless link falls below a threshold, which is specific to each receiving device, then the data rate deteriorates significantly. The reception performance in open space between the access point and the receiving unit is approximately inversely proportional to the square of the distance.

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