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Wi-FM listens to FM signals to determine best times to send and receive data

mccormick.northwestern.edu

1–10 of 18 posts

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#3
Doesn't the WiFi standard already do this for devices running in the same channel? I.e. if 3 devices are on Channel 1 they will talk to each other to avoid conflicts. Hence why you should only use one of 3 channels (the only 3 which never overlap)

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#5

Doesn't the WiFi standard already do this for devices running in the same channel? I.e. if 3 devices are on Channel 1 they will talk to each other to avoid conflicts. Hence why you should only use one of 3 channels (the only 3 which never overlap)

That is the popular wisdom, but in my experience it's not universally true. I have had good results in an apartment building by choosing channels between 1, 6, and 11. Signal strength sometimes went up quite a bit.

For example, if there are 3 APs on each of the three non-overlapping channels, using a channel between those channels may provide better results than directly competing with 3 other APs for the entire channel.

However, it also depends on the observed signal strength for each of the competing APs. For best results, you should probably test your equipment.

But if you really want decent transfer rates between devices, just use Ethernet. I've given up on ever reaching even 50% of rated speeds on wifi. With competing APs, walls, distance, etc, it's just never going to happen.

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#6
The article is somewhat confusingly worded (the actual paper it links is more clear: http://networks.cs.northwestern.edu/publications/wifm/icnp20...) and I initially thought it was describing something like Microsoft's White Spaces project where devices would automatically transmit over unused spectrum. In reality, the idea is that the devices all automatically select timing relative to an FM Radio Data System transmission and then can infer each other's chosen timing without actually communicating (or they "implicitly communicate" in the words of the paper's author as quoted in the article).

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#7
Paper http://networks.cs.northwestern.edu/publications/wifm/icnp20...

> We show that the digital signal that accompanies broadcast FM radio has sufficient structure to enable effective scheduling relative to it. It thus provides a common reference for neighboring devices to harmonize their transmissions, yet without requiring any explicit communication among them.

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#8

Doesn't the WiFi standard already do this for devices running in the same channel? I.e. if 3 devices are on Channel 1 they will talk to each other to avoid conflicts. Hence why you should only use one of 3 channels (the only 3 which never overlap)

That is the popular wisdom, but in my experience it's not universally true. I have had good results in an apartment building by choosing channels between 1, 6, and 11. Signal strength sometimes went up quite a bit. For example, if there are 3 APs on each of the three non-overlapping channels, using a channel between those channels may provide better results than directly competing with 3 other APs for the entire chan…

The solution to all wireless problems is... wires.

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#9
post #8

Earlier quoted context omitted.

That is the popular wisdom, but in my experience it's not universally true. I have had good results in an apartment building by choosing channels between 1, 6, and 11. Signal strength sometimes went up quite a bit. For example, if there are 3 APs on each of the three non-overlapping channels, using a channel between those channels may provide better results than directly competing with 3 other APs for the entire chan…

The solution to all wireless problems is... wires.

Makes me hope that "li-fi" pans out.

Basically combo powerline data with rapidly blinking (1000+ hz, iirc) leds to be able to give specific rooms wireless data. And if the light is polarized, a simple coating on the windows that match can let light in, but not data out.

Re: Wi-FM listens to FM signals to determine best times to send and receive data

#10

The article is somewhat confusingly worded (the actual paper it links is more clear: http://networks.cs.northwestern.edu/publications/wifm/icnp20... ) and I initially thought it was describing something like Microsoft's White Spaces project where devices would automatically transmit over unused spectrum. In reality, the idea is that the devices all automatically select timing relative to an FM Radio Data System trans…

So a transmission time slot selector seeded by FM signals. I haven't read it yet, but is there a good summary for how it handles varying loads? As the number of users and packets go up, you have to select smaller timeslots from the same FM signal seed.
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