For the last decade or so, wireless networking has been entirely about short range, high speed communications. The type of networking needed by an Internet of things is fundamentally incompatible with WiFi, and the reason for this is due to the frequencies used by WiFi networking gear. 2.4 and 5 GHz are very fast, but cannot penetrate through walls as easily as lower frequencies.
This week the WiFi alliance introduced IEEE 802.11ah into the WiFi spec. It’s called WiFi HaLow (pronounced like angel’s headwear), and unlike other versions of 802.11, WiFi HaLow uses low frequencies for low bandwidth but a much larger range.
WiFi HaLow uses the 900 MHz ISM band to communicate, divided into 26 channels. The bandwidth is low – a mere 100 kbps, but the range is huge: one kilometer, or about four times the approximate range of 802.11n.
This is not the only WiFi spec aimed at the Internet of Things. In 2014, the WiFi alliance introduced 802.11af, a networking protocol operating in unused TV whitespace spectrum between 54 and 790 MHz. 802.11af has a similar range as 802.11ah – about one kilometer – but products and chips utilizing 802.11af have been rare and hard to find.
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The equipment is big and expensive, with the research costs at almost $500,000. But by just using retail components, Chinese professor Chi Nan has built her own Li-Fi wireless system that can use LED lights to send and receive Internet data.
“I bought the lights from Taobao,” she said, referring to the Chinese e-commerce site.
The professor from Fudan University showed off the technology on Tuesday at the China International Industry Fair in Shanghai. Unlike traditional Wi-Fi routers that use radio signals, Chi’s system relies on light to send and receive data wirelessly.
Other scientist, especially in the U.K., have also been researching the technology, and dubbed it “Li-Fi”. But rather than develop specialized hardware, Chi bought off-the-shelf retail parts to create her system.
Chi, an expert on optical fibers, said on the side lines of the trade show that she was simply interested in the promise of Li-Fi. “I just wanted to play around,” she said. Funding also came from the local Shanghai government, which has made research in the area a goal.
While Li-Fi is still in its early stages, the technology could provide an alternative to using radio waves for wireless Internet access. Currently, household Wi-Fi routers and mobile telecommunication towers depend on radio signals to send data wirelessly. But the amount of radio spectrum is limited.
Li-Fi, however, could be deployed in everyday LED bulbs, with light-based Internet connections covering the interior of entire homes or buildings. The data connection speeds can also reach several gigabits per second. Chi’s own system runs at 150 Mbps by using a small number of LED bulbs each at one watt.
“With a more powerful LED light, we can reach 3.5 Gbps speeds,” she added. Both the router and receiver are fitted with LED bulbs so that they can send data, and also installed with a chip that can process the signals.
But Li-Fi isn’t without its drawbacks. Because it is dependent on light, the technology can’t penetrate walls or work in complete darkness. In Chi’s case, the Li-Fi receiver must be within three meters of the router, and placed under the LED bulbs so that the sensor can read it.
In addition, her system is not exactly portable. The first model is quite large, with the Li-Fi receiver itself is about the size of a video game console. A second model was made to compact the parts, and that Li-Fi receiver resembles closer to a mini desktop PC. On Tuesday, the receivers were shown connected to two nearby laptops via ethernet cable.
“There are still many problems that need to be resolved,” Chi said, pointing to the need to improve the Li-Fi coverage, and miniaturize the needed components.
Over time, however, the Li-Fi receiver could conceivably take the form of a USB dongle that attaches to a notebook. Chi estimates it will take another five years before the technology can enter the market as consumer products. So far, her team has spent about 18 months on the project.
Extension of cable-based telecommunication networks requires high investments in both conurbations and rural areas. Broadband data transmission via radio relay links might help to cross rivers, motorways or nature protection areas at strategic node points, and to make network extension economically feasible. In the current issue of the nature photonics magazine, researchers present a method for wireless data transmission at a world-record rate of 100 gigabits per second.
In their record experiment, 100 gigabits of data per second were transmitted at a frequency of 237.5 GHz over a distance of 20 m in the laboratory. In previous field experiments under the “Millilink” project funded by the BMBF, rates of 40 gigabits per second and transmission distances of more than 1 km were reached. For their latest world record, the scientists applied a photonic method to generate the radio signals at the transmitter. After radio transmission, fully integrated electronic circuits were used in the receiver.
“Our project focused on integration of a broadband radio relay link into fiber-optical systems,” Professor Ingmar Kallfass says. He coordinated the “Millilink” project under a shared professorship funded by the Fraunhofer Institute for Applied Solid State Physics (IAF) and the Karlsruhe Institute of Technology (KIT). Since early 2013, he has been conducting research at Stuttgart University. “For rural areas in particular, this technology represents an inexpensive and flexible alternative to optical fiber networks, whose extension can often not be justified from an economic point of view.” Kallfass also sees applications for private homes: “At a data rate of 100 gigabits per second, it would be possible to transmit the contents of a blue-ray disk or of five DVDs between two devices by radio within two seconds only.”
In the experiments, latest photonic and electronic technologies were combined: First, the radio signals are generated by means of an optical method. Several bits are combined by so-called data symbols and transmitted at the same time. Upon transmission, the radio signals are received by active integrated electronic circuits.
The transmitter generates the radio signals by means of an ultra-broadband so-called photon mixer made by the Japanese company NTT-NEL. For this, two optical laser signals of different frequencies are superimposed on a photodiode. An electrical signal results, the frequency of which equals the frequency difference of both optical signals, here, 237.5 GHz. The millimeter-wave electrical signal is then radiated via an antenna.
“It is a major advantage of the photonic method that data streams from fiber-optical systems can directly be converted into high-frequency radio signals,” Professor Jürg Leuthold says. He proposed the photonic extension that was realized in this project. The former head of the KIT Institute of Photonics and Quantum Electronics (IPQ) is now affiliated with ETH Zurich. “This advantage makes the integration of radio relay links of high bit rates into optical fiber networks easier and more flexible.” In contrast to a purely electronic transmitter, no intermediate electronic circuit is needed. “Due to the large bandwidth and the good linearity of the photon mixer, the method is excellently suited for transmission of advanced modulation formats with multiple amplitude and phase states. This will be a necessity in future fiber-optical systems,” Leuthold adds.
Reception of radio signals is based on electronic circuits. In the experiment, a semiconductor chip was employed that was produced by the Fraunhofer Institute of Applied Solid State Physics (IAF) within the framework of the “Millilink” project. The semiconductor technology is based on high-electron-mobility transistors (HEMT) enabling the fabrication of active, broadband receivers for the frequency range between 200 and 280 GHz. The integrated circuits have a chip size of a few square millimeters only. The receiver chip can also cope with advanced modulation formats. As a result, the radio link can be integrated into modern optical fiber networks in a bit-transparent way.
Already in May this year the team succeeded in transmitting a data rate of 40 gigabits per second over a long distance in the laboratory using a purely electronic system. In addition, data were transmitted successfully over a distance of one kilometer from one high-riser to another in the Karlsruhe City center. “The long transmission distances in “Millilink” were reached with conventional antennas that may be replaced by fully integrated miniaturized antenna designs in future compact systems for indoor use,” says Professor Thomas Zwick, Head of the KIT Institut für Hochfrequenztechnik und Elektronik (Institute of High-Frequency Technology and Electronics). The present data rate can be still increased. “By employing optical and electrical multiplexing techniques, i.e., by simultaneously transmitting multiple data streams, and by using multiple transmitting and receiving antennas, the data rate could be multiplied,” says Swen König from the KIT Institute of Photonics and Quantum Electronics (IPQ), who conceived and conducted the recent world-record experiment. “Hence, radio systems having a data rate of 1 terabit per second appear to be feasible.”
It was rumored back in March that Amazon had been awarded a $600 million contract by the CIA to develop a cloud computing infrastructure for the clandestine agency. It is believed that this new infrastructure will cut costs for the CIA as it looks to build a new way to handle enormous amounts of data efficiently.
When Amazon was named as the provider, IBM moved the court to reopen bidding for the contract. IBM had concerns on the process through which the contract had been awarded to Amazon, it believed that the prices were not properly evaluated and that a contract requirement had been waived for Amazon. The effort to reopen bidding has been squashed by Amazon in court.
The hammer was laid down by Judge Thomas Wheeler of the U.S. Court of Federal Claims in Washington. IBM is obviously not happy. The company says in a statement that it is “disappointed” with the ruling made by the court and that it plans to file an appeal against this decision.
IBM goes on to say that in light of current times this decision is “especially inappropriate,” adding that IBM’s bid was superior in a number of ways while also being “substantially more cost-effective.” Amazon is yet to comment on this ruling, but it seems to be far from a victory, given that IBM is showing no signs of backing off any time soon.
Inlfight internet service Gogo announced today that it plans to bring new technology to partner airlines in the US that will provide more than 60 Mbps starting with Virgin America flights in the second half of next year. Dubbed “Gogo GTO” or “Ground to Orbit,” the new service offers a 20-fold increase in speeds up from the peak 9.8Mbps delivered through Gogo’s current network.
“Because we are a Silicon Valley-based airline, Virgin America guests expect a fully connected in–flight experience that enables them to remain productive even at 35,000 feet,” said President and CEO of Virgin America David Cush. “We were proud to be the first to offer Gogo’s ATG-4 product last year and we are pleased to be the launch partner for GTO, which will be another leap forward in terms of speed and performance of in–flight Wi-Fi for our guests.”
Gogo will first have to get FAA approval before rolling out next year. But when it does, this is how it will work:
Gogo will be utilizing a Ku antenna developed specifically for receive only functionality. The advantages of using satellite for reception only and Gogo’s ATG Network for the return link are unprecedented. Existing two-way satellite antennas in the commercial aviation market have limited power for transmissions so they don’t interfere with other satellites. This dynamic makes the connection from the aircraft to the ground using two-way satellite an inefficient and expensive return link compared to Gogo’s ATG Network. Gogo’s receive only antenna will be two times more spectrally efficient and half the height of other antennas in the commercial aviation market. The low profile of the antenna will result in much less drag and therefore fuel burn on the aircraft and, ultimately, greater operational efficiencies for airlines.
The Federal Communications Commission has proposed a plan to free up more spectrum in the 5GHz range for Wi-Fi purposes. Speaking at an event in Las Vegas today, FCC Chairman Julius Genachowski said that the freed spectrum will relieve the congestion and “traffic jam” that currently constricts Wi-Fi networks today. The extra spectrum is currently used by the Department of Defense, and will be shared with government purposes should the proposal be approved. Genachowski did not say how much spectrum the proposal would allocate for Wi-Fi networks, but he did note that it would be a substantial amount. The FCC is due to review the proposal next month.