Telecommunications

Wi-FM uses local radio stations to improve Internet speeds

Wi-FM uses local radio station...
Researchers have created a way to improve Wi-Fi speeds, using existing FM radio stations
Researchers have created a way to improve Wi-Fi speeds, using existing FM radio stations
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Researchers have created a way to improve Wi-Fi speeds, using existing FM radio stations
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Researchers have created a way to improve Wi-Fi speeds, using existing FM radio stations

Wi-Fi connections are great when they work quickly and efficiently, but when they suddenly slow down inexplicably it can be very frustrating. Surprisingly, this isn't usually caused by a slow connection from your ISP, rather it occurs when two physically close Wi-Fi connections interfere with each other. Now researchers from the McCormick School of Engineering at Northwestern University have come up with a simple way to prevent this – and improve Wi-Fi speeds – by using Frequency Modulation (FM) and a smart time-sharing system that maximizes data throughput.

Dubbed Wi-FM by its creators, the system aims to prevent a person's network data from competing with a neighbor's data when packets of network data are transmitted at the same time. This is because data packets "bump into" each other if two networks transmit at the same time. Slow Internet speeds are the result, because both packets automatically back off when this occurs and stop moving toward their destinations.

"Most people think it's a mystery," says Aleksandar Kuzmanovic, associate professor of electrical engineering and computer science at Northwestern. "They get upset at their routers. But what's really happening is that your neighbor is watching Netflix."

The protocols built into Wi-FM, on the other hand, allow the device to monitor the network and choose the least busy time slots in which to transmit FM radio signals.

"It will listen and send data when the network is quietest," says PhD student Marcel Flores. "It can send its data right away without running into someone else or spending any time backing off. That's where the penalty happens that wastes the most time."

The team's method enables existing wireless networks to communicate through current commercial FM radio signals, constantly transmitted through the spectrum from 87.5 Mhz to 108 Mhz. To do this, the device effectively transmits signals that are synchronized with the digital information transmitted on the RDS (Radio Data System) section of a transmitted FM signal.

Designed to improve the usability and versatility of FM radio, the RDS is a method by which digital information pertaining to the content – such as station information for display on modern receiver displays, program information, and traffic alerts – is relayed on a sub-carrier to the main transmission frequency. This information also contains time signals regarding the broadcast, and it is these signals that the McCormick Engineering team uses to allow their system to determine the "quiet" intervals in which the WiFM can transmit with the least interference.

As such, as the device monitors the network, it also monitors the traffic in that network and considers the volume of data flow occurring in physically nearby signals. In this way, it times data packet transmissions into slots of time within the best frequency space to avoid cross-talk and interference with other signals. Happening at exceptionally fast speeds, though, the network itself sees no gap in transmission or reception as each data packet is transferred and, in the case of streaming music or video, continuously cached on a local machine.

FM was also chosen for its ubiquity; most smartphones and other mobile devices already come standard with an embedded FM chip. FM is also very reliable in its transmission and reception behaviors and, at the frequencies transmitted, is more easily able to travel through solid obstructions such as buildings. According to the team, minor software upgrades to connected devices may also be possible by using the Wi-FM system to carry them.

"Our wireless networks are completely separate from each other," says Flores. "They don't have any way to talk to each other even though they are all approximately in the same place. We tried to think about ways in which devices in the same place could implicitly communicate. FM is everywhere."

Because the Wi-FM system also sees the usage patterns of other nearby networks so as to detect times of light and heavy traffic, it can also adapt its behavior automatically as those patterns change. "Our system can solve these problems without involving real people," says Kuzmanovic. "Because are you going to knock on 30 doors to coordinate your wireless network with your neighbors? That is a huge management problem that we are able to bypass."

The results of this research were recently presented in a paper to the 23rd Annual IEEE International Conference on Network Protocols in San Francisco. Source: Northwestern University

2 comments
Daishi
There could be a little confusion here, "FM" was used to describe FM radio because it used Frequency Modulation instead of Amplitude Modulation like AM radio. Essentially all modern communication uses frequency modulation among other more complex systems. What they are talking about here is the FCC licensed FM radio spectrum. They want to transmit data over range using the side bands of licensed spectrum and they don't believe they will interfere. I have to disagree. First of all, the guard/side bands are there for a reason and nobody outside the licensed owners of the spectrum should probably transmit within those allocated frequencies. It's very easy to generate "noise" that may not impact people close to the FM tower but if I have a weak signal on a radio station and all my neighbors WiFi routers are transmitting much stronger signals (from the perspective of my receiver) it could generate noise or interference that would make my signal harder to decipher. I don't trust consumer grade WiFi routers not to be noisy or bleed to other spectrum either. The next probably more important point is time slots vs propagation delay. Propagation delay is a major problem so just because my WiFi router sees an available time slot based on my receive time doesn't mean a receiver in a totally different direction won't receive my signal and the licensed FM radio sideband signal with a totally different amount of delay which could totally invalidate my chosen time slot. In a hypothetical example I might be 5 ms west of the FM tower, by the time someone 5 ms east of the fm tower receives my data will be at a 10 ms delay compared to the tower at 5 ms. This works over short ranges or while a central receiver is coordinating time slots for "clients" but it would not work as described here. It only works with cell towers because the cell tower centrally controls the client receivers (cell phones) and is able to individually allocate time slots accounting for propagation delay using itself as the point of reference because the phones don't communicate directly without a centralized controller. Without centralized control, with some receivers only able to hear some other receivers, and adding propagation delay the design would be subject to a massive amount of collisions. The larger the range of communication the more propagation delay and interference becomes a problem. Because FM radio bands communicate over such long ranges and its such a small sliver of spectrum it would be very very limited in usefulness for scaling WiFi. Scaling WiFI often involved not using 2.4GHz and only using the 5Ghz band because the 2.4G band is crap and this method would make that an order of magnitude worse rather than better and step on legitimate licensed FM radio stations in the process. I do think it would be fine if the licensee of the spectrum (the radio station) pushed more data besides just RDS on the spectrum they own in a broadcast fashion. I think that is something already being done in limited deployment today for things like traffic data over FM bands and XM/satellite. There is no reason that things like software updates couldn't be pushed by broadcast to a caching system using the same method.
JosephRotello
<< Wi-FM uses local radio stations to improve Internet speeds >> As long as they do NOT send / receive signals off of the AC power line, and they do NOT use noisy switching power supplies in all this...more power to them.