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New York Mayor Bill de Blasio (R) and New York Governor Andrew Cuomo (C) stand in front of a mangled dumpster while touring the site of an explosion that occurred on Saturday night on September 18, 2016 in the Chelsea neighborhood of New York City.

Lessons From the New York Bombing

Late in the evening of Saturday, Sept. 17, New York City residents living in Manhattan’s Chelsea district received some unsettling news via their cellphones. After hearing an emergency alert, they were informed that there had been a bomb blast in their neighborhood, and that they should stay inside and away from their windows until further notice.

An attack based on an Improvised Explosive Device, or IED—a hallmark of the wars in Iraq and Afghanistan—had once again wreaked havoc in a major U.S. city. The Chelsea explosion, which injured 29 people, was one of a series of attacks and related events that ended with the arrest of a 28-year-old suspect in Linden, New Jersey on Monday morning. The events began with a pipe-bomb explosion near the seashore in New Jersey, on Saturday morning, and continued on Saturday night with the Chelsea bombing, on West 23rd Street in Manhattan and the discovery of another bomb near the Chelsea site. On Sunday night, five other bombs were found in a backpack in Elizabeth, New Jersey. All of the bombs are believed to be the work of a single person.

For Col. Barry Shoop, head of the Department of Electrical Engineering and Computer Science at the U.S. Military Academy at West Point, the attacks were a grim confirmation of a long-held belief. “If we can’t solve this problem outside of the United States, we are going to see them [IEDs] inside the borders of the United States,” he said in an interview shortly after the arrest of the suspect. In a podcast interview with IEEE Spectrum in 2013, after an IED killed 3 and wounded 264 in Boston, Shoop pointed out that every month there were 400 to 500 IED “events” around the world, not including Afghanistan. (Shoop is also the current president of the IEEE.)

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A silver tower lined with antennas against a clear blue sky broadcasts cellular signals.

"Real 5G" Will Broadcast Above 6 Gigahertz, Says Analyst

Brace yourself—the debate over what should and shouldn’t count as 5G has only begun. Defining the next generation of wireless networks is complicated, partly because engineers are developing so many exciting technologies at once and have yet to agree on the standards by which they will operate.

Within that murkiness is plenty of room for disagreement over how and where 5G will emerge. Stéphane Téral, an analyst at IHS Markit, recently weighed in by criticizing the use of “5G” to describe sub-6 gigahertz developments in a research note.

Radio waves in the sub-6 GHz range are considered the most desirable among carriers for delivering cellular signals because they can penetrate materials such as concrete and glass. Two ranges in particular—frequencies around 800 megahertz and 1.9 GHz—have long dominated the U.S. cellular landscape.

But these frequencies are becoming crowded as more users consume more data on more devices. And a bevy of other consumer technologies including Wi-Fi, Bluetooth, microwave ovens, and satellite radio operate at frequencies between 1.9 GHz and 6 GHz. So carriers have begun to browse higher frequencies for open bands that they can co-opt for cellular use.

Many have set their sights on much shorter millimeter waves that fall between 30 and 300 GHz. There are plenty of frequencies available in the millimeter-wave range, because they’ve been used only for specialized applications such as remote sensing and military radar. But waves at these frequencies can’t travel as far or make it through as many obstacles, so companies and researchers are still figuring out what it would mean to integrate them into future 5G networks.  

“Obviously, the low latency and high bandwidth stuff like AR and VR will definitely benefit from millimeter wave,” says Anshel Sag, a 5G analyst for Moor Insight & Strategy. “But the way the technology works right now, it’s still pretty power hungry and requires a complicated array of antennas.”

Given the situation, Téral says it’s not surprising that carriers are also focused on finding more efficient ways to deliver data on lower sub-6 GHz frequencies. They’re improving their networks through technologies such as multiple input and multiple output (MIMO), in which carriers add antennas to existing 4G base stations to handle more traffic from more users at once.

In fact, some companies have begun to concentrate their 5G efforts on these kinds of sub-6 GHz improvements. Chinese smartphone manufacturer Huawei has said that sub-6GHz bands will be “the primary working frequency” for 5G, and Qualcomm recently announced a new 5G radio prototype focused on the same batch of frequencies.

But Téral is irked by companies who dub these developments 5G. He says only advancements at higher frequencies (those above 6 GHz) should count as “real 5G,” because they would represent a paradigm shift for improving data rates and latency on future wireless networks. He argues that sub-6 GHz improvements incorporated into existing 4G and 4G LTE networks are simply business as usual.

“The cellular guys want to use that spectrum to make a 5G claim, but this is not a dramatic move from where cellular is, from 700 MHz to 2.6 GHz,” he says. “You really want to call that 5G? It doesn't justify a generational jump.”

However, other experts say the importance of millimeter waves to 5G has been overstated, and key developments at lower frequencies, including the repurposing of TV white space, will play a significant role in enabling faster mobile connections, connected cars, and the Internet of Things.

Sag thinks it’s a mistake to rule out anything other than millimeter waves as true 5G. He says 5G New Radio, a wireless standard defined by the global wireless standards group 3GPP, should count as 5G no matter which frequencies it handles. Many others also envision future 5G networks as a blend of millimeter waves and sub-6 GHz technologies.

“I'm in the camp that doesn't believe that millimeter wave is the only way to do 5G,” Sag says. “In fact, I think it's the wrong way of doing 5G if you think of it as the only way of doing it.” Instead, Sag believes 5G will permeate every swatch of spectrum from the low frequencies used for NarrowBand IoT all the way up to high-frequency millimeter waves.

Téral admits progress in the sub-6 GHz range is an important first step in the “pre-5G” evolution of wireless. He also acknowledges that many of the potential uses that experts have dreamt up for 5G can and will be achieved through incremental improvements to 4G LTE networks. But he says he’d prefer to call those improvements “transitional 4G” instead. “There’s nothing new, and that’s the whole point,” he says.

To Sag, the matter of what counts as 5G is not just a theoretical debate: It could have a real impact on the trust that consumers place in carriers. “My biggest concern is kind of the same concern with 4G, in that the definitions get muddled and the consumers get confused,” he says.

A close up of the Haswell-EX Xeon E7-8890 V3 multicore processor chip shows 18 cores.

New System Could Break Bottleneck in Microprocessors

Engineers at North Carolina State University and at Intel have come up with a solution to one of the modern microprocessor’s most persistent problems: communication between the processor’s many cores. Their answer is a dedicated set of logic circuits they call the Queue Management Device, or QMD. In simulations, integrating the QMD with the processor’s on-chip network, at a minimum, doubled core-to-core communication speed, and in some cases, boosted it much farther. Even better, as the number of cores was increased, the speed-up became more pronounced.

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A picture of the 6 mm x 2 mm photonic integrated circuit chip, containing two quantum random number generators

A Chip-Scale Source for Quantum Random Number Generators

Taking advantage of technology developed to manipulate light on chips, a team based in Spain and Italy has created an integrated circuit that can be used to generate true random numbers by taking advantage of the thoroughly unpredictable nature of quantum mechanics.

The compact approach, which might one day find its way into smartphones and tablets, could be a boon for engineers hoping to keep financial transactions and other communications secure. Random numbers are a vital ingredient in the encryption schemes we rely on to secure data, and they’re also a powerful tool in computational modeling. 

Today’s conventional random number generation is done using computer algorithms or physical hardware. A chip-based random number generator can, for example, use analog or digital circuits that are sensitive to random thermal fluctuations to generate unpredictable strings. 

But even if these sources look quite random, it’s practically impossible to prove they are perfectly so, explains Valerio Pruneri of the Institute of Photonic Sciences in Spain. If you wait long enough—perhaps far longer than you’d care to wait—you may ultimately find there are correlations between numbers, ones that would ultimately allow you to crack the random-number-generation scheme. 

Systems that obey the rules of quantum mechanics, by contrast, could be impossible nuts to crack. “Quantum physics, by definition, is fully unpredictable no matter what,” Pruneri says. “There is no way that somebody can guess future numbers based on current information.”

Quantum random number generators are nothing new; there are even commercial systems available. But Pruneri and his colleagues decided to take aim at portability. They wanted to create something that could spit out random numbers at a high rate, but be small and energy-efficient enough that it could ultimately be integrated with microelectronics—perhaps in a package small enough to fit in a smartphone or tablet.

The chip they created takes advantage of standard fabrication techniques used to construct photonic integrated circuits. A small, pulsed indium phosphide laser is responsible for infusing the system with randomness. Below a certain energy threshold, a laser emits a small number of photons through a process called spontaneous emission, which creates light with random phase. This randomness impacts the ultimate phase of the light the laser emits when it’s above that threshold, once stimulated emission starts to dominate, Pruneri explains. The result is that, pulse to pulse, the laser light will have a random phase.

To transform these random phases into something usable, the pulsed light is mixed with light from a second indium phosphide laser on the chip. The phase of the first laser’s pulses will ultimate impact how light from the two laser sources interfere with one another, creating certain brightness differences that can be read out by a photodetector.

This quantum “entropy source” can be used to produce random numbers at a good clip—in the realm of a gigabit per second. The work appears online today in the journal Optica

Pruneri says the next step is to integrate the chip with conventional CMOS electronics to turn the output of the system into random numbers that can be used by software. Here too, he expects the team will take advantage of photonics integrated circuit manufacturing techniques that have been built up over the years, in particular a way of pairing silicon and other materials, called hybrid integration.

Illustration: Akshat Wahi/MIT

Handy Device + Phone App Tells if Fruit Is Ripe

Want an apple with a perfectly crisp, sweet, juicy bite? A new handheld device can help. Researchers have made a portable spectrometer that scans fruit and wirelessly relays data to a smartphone app that tells you whether the fruit is ripe.

Unlike the bulky, expensive spectrometers used today to test food and drug quality, the new gadget is about the size and weight of a collectible matchbox car. It consumes little power, and it costs less then $250 according to its inventors at MIT.

Farmers could use the smartphone-based device in the field to determine the ideal harvesting time for apples and other fruit, the inventors say. Or it could find use in storage facilities to sort fruit and vegetables and to check ripeness. It could also be adapted for consumers, helping them avoid the unpleasantness of tart or rotten fruit.

The food industry today uses one of two methods to test apple ripeness. One is to measure firmness using penetrometers and sclerometers. Both devices rely on measuring the force required to insert a probe into the fruit. The other test in use today, called Brix, measures the sugar content of the fruit juice using light refraction. Both methods are destructive, says MIT Media Lab researcher Anshuman Das.

Das and his colleagues turned to optical spectroscopy instead. “We use light to probe the sample, making the technique rapid and non-destructive,” he says.

The team bought a spectrometer chip and packaged it along with an ultraviolet LED, optical filters, a Bluetooth module for wireless data communication, an Arduino microcontroller for analog-to-digital conversion, and a rechargeable lithium-ion battery into a small 3D printed case.

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The iPhone 7 and its earphones

iPhone 7 Ditches the 3.5-mm Analog Audio Jack

The iPhone 7 is officially on its way, and the new model has one conspicuous absence: it lacks the 3.5-mm analog audio jack that customers have used to plug in headphones or speakers since the first iPhone was released in 2007. Without it, Apple users will have to switch to wireless headphones or digital ones that plug into the iPhone’s Lightning cable port. That's the same port used to charge the device or connect it to a laptop.

Apple is not the first smartphone manufacturer to remove the familiar analog audio jack from its phones—the Chinese company LeEco rolled out three such models last spring and then rival Lenovo debuted the jackless Moto Z earlier this summer. After Apple’s announcement, even more manufacturers are expected to follow suit.

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A crowd waits at JFK International Airport due to reports of shooting inside a terminal

Modern Airports Offer No Easy Way Out for Panicking Crowds

False reports of shooters at two of the busiest U.S. airports—one in New York City and one in Los Angeles—left many passengers swept along by surging crowds of panicked people searching for the closest exits. The chaos was perhaps all too predictable, because computer simulations suggest that many major airports are terribly designed for emergency evacuations.

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The number of students graduating with engineering degrees—and training in the latest technologies—is falling far short of the pace that new openings in industry are being created.

Germany's Engineering Gap Increasing Fast With Rise of New Technologies

Between 2016 and 2026, Germany will need 100,000 more engineers in electrotechnology, electronics, and computer technology than will graduate from that nation's universities and technical colleges. The report, published by the German Association for Electrical, Electronic, and Information  Technologies (VDE), bases this estimate on employment figures obtained for the period beginning in 2005 and ending in 2013. During that time, the number of new engineering positions increased by an average of 10,500 per year, while unemployment for engineers remained low—less than 2.5 percent.

The study also reports that during this eight-year period, the number of engineers graduating in Germany would have only covered new openings caused by engineers leaving the profession, mainly from retirement. This indicates that the yearly increase in job openings in industry has been filled by an influx of engineers from Southern Europe and other countries. In 2013, 10.6 percent of the total of 381.200 electrical engineers working in Germany were foreign nationals. Extrapolating from those statistics, the authors of the report arrived at the figure of 100,000 new engineering positions that will have to be filled in the next 10 years. 

The reason for this gap is industry’s increased reliance on new technologies. According to VDE, almost 90 percent of the new engineering positions are now in the areas of digital technologies, mobility, the smart grid, and information technology. But mechanical engineering and machine manufacturing are also involved. An example is the automotive components manufacturer Bosch, which is actively seeking to fill thousands of positions in these areas.

This changeover to new technologies happens in competing countries as well, so Germany will have to look for ways to encourage  young people in Germany to study engineering rather than hope to attract them from elsewhere. Ansgar Hinz, chairman of the board of directors of VDE, in a press release (in German), blames what he calls a double gap:  “...a lack of both engineering graduates from [technical] colleges and universities.”

A world map with red dots shows all known locations of Netflix servers, with the majority concentrated in the United States and Europe and few in Africa or Asia.

Researchers Map Locations of 4,669 Servers in Netflix’s Content Delivery Network

When you open Netflix and hit “play,” your computer sends a request to the video-streaming service to locate the movie you’d like to watch. The company responds with the name and location of the specific server that your device must access in order for you to view the film.

For the first time, researchers have taken advantage of this naming system to map the location and total number of servers across Netflix’s entire content delivery network, providing a rare glimpse into the guts of the world’s largest video-streaming service.

A group from Queen Mary University of London (QMUL) traced server names to identify 4,669 Netflix servers in 243 locations around the world. The majority of those servers still reside in the United States and Europe at a time when the company is eager to develop its international audience. The United States also leads the world in Netflix traffic, based on the group’s analysis of volumes handled by each server. Roughly eight times as many movies are watched there as in Mexico, which places second in Netflix traffic volume. The United Kingdom, Canada, and Brazil round out the top five.

The QMUL group presented its research to Netflix representatives earlier this year in a private symposium.

“I think it's a very well-executed study,” says Peter Pietzuch, a specialist in large-scale distributed systems at Imperial College London who was not involved in the research. “Netflix would probably never be willing to share this level of detail about their infrastructure, because obviously it's commercially sensitive.”

In March, Netflix did publish a blog post outlining the overall structure of its content delivery network, but did not share the total number of servers or server counts for specific sites.

Last January, Netflix announced that it would expand its video-streaming service to 190 countries, and IHS Markit recently predicted that the number of international Netflix subscribers could be greater than U.S. subscribers in as few as two years. Still, about 72 percent of Netflix customers were based in the United States as of 2014.

Steve Uhlig, the networks expert at Queen Mary University of London who led the mapping project, says repeating the analysis over time could track shifts in the company’s server deployment and traffic volumes as its customer base changes.

“The evolution will reveal more about the actual strategy they are following,” he says. “That's a bit of the frustrating part about having only the snapshot. You can make guesses about why they do things in a specific market, but it's just guesses.”

Netflix launched streaming service in 2007 and began to design its own content delivery network in 2011. Companies that push out huge amounts of online content have two options when it comes to building their delivery networks. They may choose to place tons of servers at Internet exchange points (IXPs), which are like regional highway intersections for online traffic. Or, they can forge agreements to deploy servers within the private networks of Internet service providers such as Time Warner, Verizon, AT&T, and Comcast so that they’re even closer to customers.

Traditionally, content delivery services have chosen one strategy or the other. Akamai, for example, hosts a lot of content with Internet service providers, while Google, Amazon, and Limelight prefer to store it at IXPs. However, Uhlig’s group found that Netflix uses both strategies, and varies the structure of its network significantly from country to country.

Timm Böttger, a doctoral student at QMUL who is a member of the research team, says he was surprised to find two Netflix servers located within Verizon’s U.S. network. Verizon and other service providers have argued with Netflix over whether they would allow Netflix to directly connect servers to their networks for free. In 2014, Comcast required Netflix to pay for access to its own network.

Tellingly, the group did not find any Netflix servers in Comcast’s U.S. network. As for the mysterious Verizon servers? “We think it is quite likely that this is a trial to consider broader future deployment,” Böttger says. Netflix did not respond to a request for comment.

To outline Netflix’s content delivery network, Uhlig and his group began by playing films from the Netflix library and studying the structure of server names that were returned from their requests. The researchers also used the Hola browser extension to request films from 753 IP addresses in different parts of the world in order to find even more server names than would otherwise be accessible from their London lab.

“We first tried to behave like the regular users, and just started watching random movies and took a look at the network packages that were exchanged,” says Böttger.

Their search revealed that Netflix’s server names are written in a similar construction: a string of numbers and letters that include traditional airport codes such as lhr001 for London Heathrow to mark the server’s location and a “counter” such as c020 to indicate the number of servers at that location. A third element written as .isp or .ix shows whether the server is located within an Internet exchange point or with an Internet service provider.

Once they had figured out this naming structure, the group built a crawler that could search for domain names that shared the common nflxvideo.net address. The team supplied the crawler with a list of countries, airport codes, and Internet service providers compiled from publicly available information. After searching all possible combinations of those lists, the crawler returned 4,669 servers in 243 locations. (Though the study cites 233 locations, Böttger said in a follow-up email that 243 is the correct number.) 

To study traffic volumes, the researchers relied on a specific section of the IP header that keeps a running tally of data packets that a given server has handled. By issuing multiple requests to these servers and tracking how quickly the values rose, the team estimated how much traffic each server was processing at different times of the day. They tested the servers in 1-minute intervals over a period of 10 days.

Their results showed that the structure and volume of data requested from Netflix’s content delivery network varies widely from country to country. In the United States, Netflix is largely delivered through IXPs, which house 2,583 servers—far more than the 625 found at Internet service providers.

Meanwhile, there are no Netflix servers at IXPs in Canada or Mexico. Customers in those countries are served exclusively by servers within Internet service providers, as well as possibly through IXPs along the U.S. borders. South America also relies largely on servers embedded within ISP networks—with the exception of Brazil, which has Netflix servers stashed at several IXPs.

The U.K. has more Netflix servers than any other European country, and most of those servers are deployed within Internet service providers. All French customers get their films streamed through servers stationed at a single IXP called France-IX. Eastern Europe, meanwhile, has no Netflix servers because those countries were only just added to the company’s network in January.

And the entire continent of Africa has only eight Netflix servers, all of which are deployed at IXPs in Johannesburg, South Africa. That’s only a few more than the four Netflix servers the team found on the tiny Pacific Ocean island of Guam, which is home to the U.S.-operated Andersen Air Force Base.

“It's kind of striking to see those differences across countries,” Pietzuch says. “[Netflix’s] recent announced expansion isn't really that visible when you only look at the evolution of their CDN structure.”

Before the group’s analysis, Uhlig expected to see servers deployed mostly through Internet service providers as a way to ease the traffic burden for service providers and get as close as possible to Netflix’s 83 million customers. He was surprised to see how heavily the company relies on IXPs, despite the company’s insistence that 90 percent of its traffic is delivered through ISPs.

“If you really want to say, ‘I really want to be close to the end users,’ you need to deploy more, and we didn't see that,” he says. “I think the centralized approach is convenient because you have more control and you can scale things up or down according to what the market tells you.”

Uhlig didn’t expect to find Mexico and Brazil so high on the traffic list, even though Netflix has tried to expand its Spanish- and Portuguese-language offerings.

In March, the company said it delivers about 125 million total hours of viewing to customers per dayThe researchers learned that Netflix traffic seems to peak just before midnight local time, with a second peak for IXP servers occurring around 8 a.m., presumably as Netflix uploads new content to its servers. 

Before 5G takes the stage, there will be a lot of improvement in 4G wireless data service.

Finnish Carrier Sets New World Record for 4G Download Speeds

Sure, everyone’s excited about 5G, the highly anticipated next generation of wireless networks expected to deliver data so fast it will make your head spin. But the improvements in speed and capacity that 4G networks achieve today will be far more relevant to the average customer for at least the next three years.

That’s why it’s good news that Elisa, a Finnish carrier, announced what it says is a new world record for 4G download speeds. The company used the latest 4G technology from Huawei to achieve a top speed of 1.9 gigabits per second last week in a Helsinki lab. Sami Komulainen, vice president of mobile network services, says he hopes to use this technology to offer customers a data package with 1 Gb/s download speeds within “a few years.”

Finland is a fitting place for carriers to push the limits of 4G network speeds and capacity. Finns consume more data per capita than any other nation, with the average active user on Elisa’s network devouring 12 gigabytes of data per month. This compares with 2 GB per person in other developed economies. To put this into perspective, Komulainen says Finland, with an estimated 3 million smartphone users, consumes about the same amount of data as India’s 220 million smartphone users.

The standard mobile phone plan in Finland comes with unlimited data, and carriers differentiate their services based on speed. Elisa’s network currently maxes out at 450 megabits per second; it sells data packages that offer speeds up to 300 Mb/s.

And the rest of the world could soon behave a lot more like the Finns do. Worldwide, carriers anticipate ever more demand for 4G service, long before 5G is expected to roll out in the early 2020s. Cisco estimates that global mobile data traffic will rise eightfold from 2015 to 2020.

With 5G on the (somewhat distant) horizon, some carriers have begun to speak of building a new “4.5G” network as they move beyond the speeds and capacity that have long defined 4G service.

The Elisa test relied on a suite of wireless strategies and technologies including five-carrier aggregation (a technique that lets users blend results from five carriers for better service), 4x4 MIMO (which refers to the structure of the base station radio unit and antennas), and 256 QAM (which indicates how the amplitude of radio signals is modulated). It was the first time that this particular blend of strategies was used in combination with Huawei's latest LTE-Advanced Pro technology.

Though Elisa may have posted the most impressive speeds to date, plenty of other carriers are running similar tests. In February, Australia-based Optus achieved peak 4G download speeds of 1.23 Gb/s and cited a “theoretical maximum” of 1.43 Gb/s based on its network and the Huawei technology in use.

“I think all of [the carriers] are in the 1 Gb/s range; Elisa's beyond [the rest] slightly, but I think they're all in a similar ballpark,” says Janette Stewart, an analyst who specializes in wireless and spectrum at Analysys Mason in London. “As soon as you've got one operator achieving that, then immediately you'll have others following.”

The new speed test doesn’t mean Elisa customers should expect lightning-fast downloads to begin tomorrow. Maximum speeds achieved in a lab under ideal conditions are not generally repeatable in a real network. Elisa ran its test on a base station serving a single terminal, or user. The researchers used five frequency bands (800, 900, 1800, 2100, and 2600 megahertz) to transmit signals, but in their actual network, some of those bands are reserved for 2G and 3G service.

However, Stewart expects that eventually, customers should see a difference if Huawei’s new technology is deployed across the network. “Not all users will get the peak speed, but the average speed that everybody gets should push up as a result of having this technology,” she says.

Though his immediate focus remains on improving 4G service to data-hungry Finns, Elisa’s Komulainen can’t resist thinking about what the company’s latest progress means for the future. “I think we’re going step by step toward 5G,” he says.

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