Internet @ Meetings: Separated Wi-Fi But Still Interfering

The topic of providing Internet access at meetings keeps me interested and I have continued experimenting with different setups. One somewhat more sophisticated setup I've been working on lately is to physically separate the Wi-Fi and traffic shaping module for the meeting participants from the device that provides Internet connectivity (e.g. a 3G/LTE Router).

The best setup is of course to connect them via an Ethernet cable. In some situation this might not be possible, however, for example, when the 3G/LTE router has to sit outside the meeting room as there is no or insufficient coverage in the room. For such a scenario, a Wi-Fi link can provide the solution. But this is a bit more difficult than I thought at first. In my first setup I could only get a few megabits per second through the link.

Eventually, I figured out that the Wi-Fi access point that communicates with the participants and the Wi-Fi access point communicating with the 3G/LTE router interfere with each other, despite being on completely different Wi-Fi channels (one on channel 1, the other on channel 10). Separating the two devices by a meter and a half and the channel was suddenly much better and I could get around 15 MBit/s over the end to end channel (i.e. twice over Wi-Fi). After some more experimentation I figured out that I could even have the devices close together and get almost the full channel bandwidth (around 24 MBit/s), it's just a matter of how the antennas are placed.

Kind of reminds me of first HSDPA tests I did almost 5 years ago where slight changes in antenna orientation of the HSDPA card had stunning effects.