An Ignoble Experiment

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It can be easy to forget that "wireless" does not always refer to radio communications, though that is the most widely considered connotation. But wireless can also refer to light-based communications, which some envision as the savior of their increasingly congested RF brethren.

Different flavors of light-based communications have been around for years, but the overall concept appears to be picking up steam due to the skyrocketing congestion in radio frequencies. Throw in the ability to deploy light-based communications technology with no licensing requirements, robust security and impressive performance--when signals are not blocked--and you have the makings of an attractive complement to RF networks.

An article in this week's FierceWirelessTech takes a look at pureVLC, one of the pioneers in visible light communication (VLC). Also known as Li-Fi, this technology relies upon light in the 400 THz (780 nm) to 800 THz (375 nm) range. A related technology is free-space optics (FSO), which uses light in the infrared spectrum.

FSO is the more established of the two. San Diego-based LightPointe has long been manufacturing FSO laser bridges for point-to-point wireless connectivity. Other players in the FSO market, according to MarketsandMarkets, include Ubiquiti Networks, fSONA Networks, Northern Hi-Tec, Wireless Excellence and the Society for Optical Communications Systems.

Today's Top News

1. Ericsson, SK Telecom eliminate inter-cell handovers for faster rates, higher capacity

By Tammy Parker

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2. Apple iPhone still not supporting simultaneous voice/data for Verizon, Sprint

Infrastructure vendor Ericsson (NASDAQ:ERIC) and Korean operator SK Telecom have taken advantage of an LTE Advanced (LTE-A) capability to enable mobility without the need for an inter-cell handover between base stations.

The approach, called handover-free cell, uses adaptive coordination between base stations and mobile terminals. "When a terminal is located in a cell edge, multiple base stations adjacent to the terminal jointly transmit the same signal to it, thus removing the need for inter-cell handover," SK Telecom explained.

The result is a 1.5x to 2x increase in voice and data transmission rates and a boost in cell system capacity of five to 10 percent, the carrier added.

Key to the approach's development is the use of LTE-A's transmission mode 9 (TM-9), which defines transmissions between mobile devices and base stations. Ericsson and SK Telecom demonstrated TM-9 for the first time during January 2013, and the two began working on handover-free cell technology in March. SK Telecom said it will apply the handover-free technology to its mobile network in the first half of 2014.

Ericsson and SK Telecom also developed a technology they call reduced-power sub-frame (RPS), which is an upgrade to enhanced inter-cell interference coordination (eICIC), also a core LTE-A technology. The carrier said although eICIC reduces inter-cell interference, it also has the unattractive side effect of decreased cell system capacity.

RPS is said to reduce interference to terminals within small cells located inside of a macro cell by reducing transmission power without compromising capacity. "Compared to eICIC, RPS improves cell system capacity by as much as 62 percent," SK Telecom said.

The technology advances made with Ericsson tie into SK Telecom's Super Cell concept, announced in February at Mobile World Congress 2013. The notion is aimed at eliminating inter-cell boundaries and making multiple numbers of small cells and/or macro cells act as one by allocating identical cell IDs.

Earlier this month, SK Telecom also announced a partnership with Intel to develop vRAN, a virtualized intelligent base station that will run on universal hardware. SK Telecom said the vRAN system will reduce development time and support new technologies simply software upgrades running on standard high-volume servers.

For more:
- see this SK Telecom release

Read more about: base station, eICIC
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By Tammy Parker

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3. Li-Fi eyed as complement to Wi-Fi, cellular

A year ago, it was widely reported that the Apple (NASDAQ:AAPL) iPhone 5 would not support simultaneous voice and data for legacy CDMA operators such as Sprint (NYSE:S) and Verizon Wireless (NYSE:VZ). What a difference a year does not make. ABI Research reported that Apple still does not support SVLTE or SVDO for simultaneous voice and data in the new iPhone 5s and iPhone 5c.

The news is interesting because, ABI contends, Verizon requires its other handset suppliers to support simultaneous voice and LTE (SVLTE) and simultaneous voice and EV-DO (SVDO), and has for quite some time. But the largest U.S. operator has apparently made a unique concession in its requirements for Apple and its popular iPhones.

"It is understood that the selling power of Apple warrants some exceptions but we expected that after a year Apple would have included the capability in their iPhone 5 variants--the 5s and 5c," said Jim Mielke, ABI's vice president of engineering.

While ABI's report comments focused specifically on Verizon, it is most certain that the lack of SVLTE or SVDO support also applies to any iPhone carried by other CDMA operators, such as Sprint.

SVLTE or SVDO require two RF chains in a CDMA-based phone, but Apple apparently insists on having only one in the iPhone, which gives the device extra room to support more LTE bands while remaining thin and light. Having just one transmit chain can also improve power consumption.

Many 3GPP-based operators use circuit-switched fallback (CS-FB) to enable LTE transmissions to fall back to WCDMA/HSPA, which already multiplexes voice and data. AT&T (NYSE:T) has long marketed as an advantage the fact that its customers can simultaneously enjoy voice calls and Web surfing, unlike those on rival Verizon's network. While that comparison no longer holds true for most of Verizon's smartphone lineup, it does apparently still apply to the iPhone.

For more:
- see this ABI release

Read more about: ABI Research, AT&T
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By Tammy Parker

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4. Nokia, Juniper trumpet expanded IP partnership

Light fidelity, or Li-Fi, is being eyed as a complement to capacity-challenged Wi-Fi and cellular networks, and a spinoff from a major European university earlier this month shipped its first commercial Li-Fi product.

Li-Fi, a moniker used for visible light communication (VLC) technology, delivers wireless data via visible light spectrum instead of radio frequencies and could be used to enable LED light fittings in buildings to connect to a broadband network.

VLC supporters contend that using the vast amounts of readily available free and unlicensed visible light as well as infrared spectrum could not only solve issues of limited and congested RF spectrum but also deliver much faster wireless. Further, Li-Fi is said to over more security than Wi-Fi because VLC signals, unlike RF, cannot penetrate walls, which protects them from interference or hacking from outside their visual range.

A spinoff from Scotland's University of Edinburgh, pureVLC, has been working to commercialize light-based communications. The company, which will change its name to pureLiFi next month, just shipped its first product, an $8,000 unit delivered to an unspecified U.S. healthcare provider, according to the Financial Times.

Dr. Harald Haas demonstrates Li-Fi in this video. (Video source: TED)

Last month, the startup demonstrated that Li-Fi does not require a line-of-sight connection between the transmitter and receiver and can instead operate by using incident light, which includes reflections. PureVLC said it achieved an industry first by demonstrating high-speed Li-Fi from a reflection, streaming four videos in parallel.

Harald Haas, chair of mobile communications at the University of Edinburgh, is also co-founder and chief science officer of pureVLC. He says adding a microchip to a standard LED bulb to make it rapidly blink on and off is key to delivering binary code to a light-sensitive reciever.

"We have completed ground-breaking research demonstrating speeds up to 1.67 Gbps on a single color/LED. By the end of this year, we believe we can achieve 2 Gbps on each of the R, G, B channels, with a target of demonstrating aggregate speeds up to 6 Gbps," Haas announced in August.

He more recently told the Financial Times that pureVLC's products will initially target niche applications. But he said future growth will be driven by an impending RF spectrum capacity crunch that will hit the wireless industry hard in "two or three years" as data-centric services such as video streaming overwhelm existing networks.

However, indoor networking and location-based services are the only VLC technology applications that have so far penetrated the market, according to a report released early this year by research firm MarketsandMarkets."Products for other applications (intelligent traffic management system, in-flight entertainment, and underwater communication) are expected to hit the market by the end of 2013," said the firm.

MarketsandMarkets predicts visual light communication technology revenues will experience an estimated compound annual growth rate (CAGR) of 82 percent from 2013 to 2018, reaching a value of $6.14 billion in 2018.

In addition to pureVLC, other Li-Fi players include U.S. companies ByteLight and VX System as well as Japanese companies Nakagawa Laboratories and Outstanding Technology. The Financial Times noted that Casio has created Li-Fi applications enabling data exchanges between smartphones, while French company Oledcomm has demonstrated street lights equipped with Li-Fi.

For more:
- see this Financial Times article (sub. req.)
- see this pureVLC web page

Read more about: University of Edinburgh, VLC, LED
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By Tammy Parker

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