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It’s no secret that wireless frequency spectrum is becoming a valuable commodity. As millions and millions of users have switched from simple cell phones to new smartphone and tablet devices that carry data – as well as voice – the demands on 3G and 4G wireless systems have been on the rise, leading to what some refer to as a "spectrum crunch," one that experts predict could leave demand outstripping current capacity relatively soon (see this article and infographic from Mashable)
But amid reports of government agencies and private firms carving out their own pieces of a more highly populated wireless spectrum, there are also new reports of some technologies that could end up breaking us out of a spectrum crunch by reinventing how wireless devices transmit and receive signals. Here’s what may be a top contender to prevent or resolve a spectrum crunch.
Full-Duplex Signals and Time Domain Transmit Beamforming
A 2012 release from the University of California, Riverside (UCR) reported that its engineering professors and grad students are developing theories on spectrum use with a lot of potential to fix some spectrum problems of telecom providers. More specifically, UCR researchers believe that full-duplex radio systems could allow today’s devices to operate on half of the wireless spectrum that they currently need.
The basic idea is that while today’s cell phones and mobile devices use two separate channels for transmitting and receiving signals, it may be possible to combine both of these signals into one channel through a process that UCR researchers call time domain transmit beamforming (TDTB). Professors Yingbo Hua and Ping Liang have been working on the issue of how to implement these new full-duplex technologies and have reached out to some major telecom providers to talk about the potential for renovating cell towers and networks. Hua also has responded to basic questions from us about the potential for this new technology.
How Full Duplex Works
The actual methodologies for moving the two separate communications channels into one are heavily cloaked in engineering industry jargon (a full research paper is available here). Essentially, Hua and Liang’s methods deal with what’s called self-interference cancellation (SIC), where a full-duplex radio transmission causes strong signal interference that can drown out weaker incoming signals.
Time domain transmit beamforming can involve creating a digital tool for the radio-frequency front-end that can help a device to "hear" the weaker signals by minimizing self-interference cancellation. In responses to questions on this new technology in December 2012, the UCR team talks about finding a "needle-like window of silence" in increments, in order to work on self-interference in real time.
It might seem like telecom companies would jump at this opportunity to free up much more of the wireless spectrum and open the floodgates for additional users, but in reality, adopting this technology could involve costly overhauls. When asked about the biggest current barriers to full duplex implementation, Hua said that actual hardware implementation ranks No.1.
Government Efforts to Maximize Wireless Spectrum
At the same time that news on full-duplex technology is coming out, the Obama administration is bringing its own solution to the spectrum crunch. An official White House memo from June 2013 shows that the White House is asking federal agencies to look at unused parts of their allocated wireless spectrum that could be shared with the private sector. A Spectrum Policy Team task force was also assembled and given six months to research incentives and possibilities around this kind of sharing. Meanwhile, the Federal Communications Commission (FCC) is also pursuing the possibility of an auction of parts of the commercial spectrum.
Are government efforts and new research mutually exclusive? Not according to the engineers.
"If more spectrum becomes available," said Hua, "the time domain beamforming can also double the efficiency of the use of the new spectrum."
Telecom companies agree. Reports like this one from CNNMoney show how big wireless providers are assessing a range of options for alleviating spectrum shortages, while reports from last year show that AT&T and other companies are already setting up additional "small cell" infrastructure as a stop-gap solution.
Will the Market Decide?
Then there’s the idea of weaning more users off of the wireless networks. While the spectrum crunch, which is undoubtedly big news, seems like just another example of a consumer evolution that’s grown to become unsustainable (peak oil, anyone?), some free-market types might suggest that letting demand and supply work their magic could solve the problem "naturally." After all, streaming movies on a smartphone isn’t as vital a service as transportation or health care; it’s something that’s truly elective, a new tech luxury … although some new parents might beg to differ. Regardless of the resoundingly bad track record of free market economics in the last few decades, the lack of available network capacity for all of those YouTube and Netflix videos seems like a problem tailor-made for a "pricing solution." That means we should all be asking ourselves just how much we’re willing to pay for a full data plan. (Find out how to save on your current plan in How to Stop Overages In Your Data Plan.)
Although some technologies that could break open the wireless spectrum are a good ways off, rest assured that some top engineers are working on spectrum consolidation and efficiency. It also looks like design solutions, rather than government or market solutions, may be just around the corner.
