A new San Francisco-based start-up, Artemis Networks, announced today that it plans to commercialize its “pCell” technology, a novel wireless transmission scheme that could eliminate network congestion and provide faster, more reliable data connections. And the best part? It could work on your existing 4G LTE phone.
If it proves capable of scaling, pCell could radically change the way wireless networks operate, essentially replacing today’s congested cellular systems with an entirely new architecture that combines signals from multiple distributed antennas to create a tiny pocket of reception around every wireless device. Each pocket could use the full bandwidth of spectrum available to the network, making the capacity of the system “effectively unlimited,” says Steve Perlman, Artemis’s CEO.
First introduced in 2011 under the name DIDO (for distributed input, distributed output), pCell seems almost too fantastic to believe. And no doubt Artemis will have plenty of critics to pacify and kinks to smooth out before operators like Verizon or AT&T pay serious attention. But there are at least a couple reasons why the idea might have some real legs.
First, it’s an elegant solution to a persistent global problem. Wireless traffic ismore than doubling each year and cellular operators are struggling to keep up with that growth. “Demand for spectrum has outpaced our ability to innovate,” says Perlman, whose past entrepreneurial ventures include the cloud-based gaming service OnLive and WebTV (now MSN TV), which he sold to Microsoft in 1997.
The reason isn’t for a lack of ideas. The wireless industry is pursuing plenty of them, including small cells, millimeter-wave spectrum, fancy interference coordination, and multiple antenna schemes such as MIMO. But Perlman thinks many of these fixes are just clever kludges for an outdated system. The real bottleneck, he argues, is the fundamental design of the cellular network. “There is no solution if you stick with cells,” he says.
What’s wrong with cells? In a word: interference. Base stations and wireless devices must carefully coordinate their transmission power and spectrum use so that they don’t jam one another’s signals. This ability to divide spectrum resources among many users has been at the heart of mobile systems pretty much since they emerged in the 1980s. It’s also the reason why data rates tend to plummet when many users try to use the same cells, such as in New York City’s Times Square.
Artemis is approaching wireless transmission in a completely new way. Basically, its pCell technology could allow each wireless device to use the full bandwidth of the network regardless of how many users join and how tightly they’re packed together. It’s as if your phone were continuously the sole user of its own personal cell. Hence the name pCell.
To understand how such a system would work, let’s start with the basic set-up. To deploy the technology, an operator would first need a cloud-based data center—a rack or many racks of connected servers that would do all the heavy computation for the system. The operator would then need to install radio antennas where its customers are located, such as in homes, businesses, and city streets. Although these access points might look like small cells (Artemis’s, pictured below, are about the size of a hat box), they’re unlike ordinary base stations. “They’re dumb devices,” Perlman says, serving merely as waypoints for relaying and deciphering signals. Each one could be placed anywhere that’s convenient and would link back to the data center through a fiber or wireless line-of-site Internet connection.
Now suppose that your phone wants to connect with this pCell network. It would simply send out an access request as it normally does. And all of the “dumb” antennas in your vicinity—let’s say there are 10 of them—would pick up those signals and relay them to the data center.
That’s where things get interesting. Say, for example, you play a YouTube video. The pCell data center would request the video from Google’s servers, and then stream it to your phone through those 10 antennas. But here’s the key innovation: No one antenna would send the complete stream or even part of the stream. Instead, the data center would use the positions of the antennas and the channel characteristics of the system, such as multipath and fading, to calculate 10 unique waveforms, each transmitted by a different antenna. Although illegible when they leave the antennas, these waveforms would add up to the desired signal at your phone, exploiting interference rather than trying to avoid it.
And as you move about, and as other devices connect to and drop off the network, the data center would continuously recalculate new waveforms so that each device receives the correct aggregate signal. “There’s no handoffs and one has to take turns,” Perlman says. “You could literally light up a whole city using all the same spectrum.”
If pCell technology does take off in the next few years, it will likely be because it’s compatible with 4G LTE phones. It does this by simulating LTE base stations in software. The data center would use these virtual radios to inform its waveform calculations, essentially tricking an LTE phone into believing it’s connected to a physical base station. “Your phone thinks its the only phone in the cell and is sitting right next to the tower,” Perlman says. The same technique could also work for other wireless standards, such as 3G and Wi-Fi, he says.
So will operators adopt pCell? It’s unlikely that LTE carriers would replace their networks any time soon, even if Artemis’s technology proves to be the “seed change” Perelman believes it is. But its compatibility with LTE changes the game. For instance, operators could deploy pCell antennas in congested hot spots such as airports, sports stadiums, and city centers—places where they’re already investing in new infrastructure. Users could roam seamlessly between the two networks without having to buy new phones or switch service plans.
Artemis says it plans to license pCell to wireless carriers and Internet service providers. The company is now beginning large-scale trials in San Francisco and expects the technology will be ready for commercial rollouts by the end of 2014. It will be fascinating to see how its ambitions pan out.
Courtesy IEEE Spectrum