MIT Researchers Radically Boost Wi-Fi With Smart Routers That Talk To Each Other

From, original post here.  Written by Sean Captain, 23/8/16.

Tech lets wireless access points cancel out interference, providing a speed boost for crowded venues. It might help cellphone towers, too.

Look at the night sky on a camping trip and the stars are everywhere.  Look from a city full of lights and you barely see any.  The disappointment is similar when you go from a Wi-Fi network in isolation to one crowded with dozens, maybe hundreds, of other users.  The problem, in both cases, is interference: signals crashing into each other.  Adding more Wi-Fi access points, or APs, to extend the coverage area can cause more collisions, since they are all fighting over the same limited spectrum.

Now MIT researchers say they’ve found a fix: getting APs to anticipate how they will collide and tweak the signals to undo the damage.  In today’s world of busy Wi-Fi networks, the way to avoid a crash is to take turns, like cars meeting at a four-way stop sign.

“If you’re the only person, you get to send [data] all the time,” says Hariharan Rahul, a visiting researcher at MIT’s Computer Science and Artificial Intelligence Lab.  “If there are two people you get to send … about half the time.  As there are more and more people, you get less and less opportunities to send.”

Rahul worked with two PhD students and professor Dina Katabi on a new solution: Instead of avoiding collisions, take advantage of them.

Now get ready for the jargon salad.  The technology MIT developed is named MegaMIMO 2.0. (It’s an extension of a technology called MIMO that coordinates multiple antennas inside a single AP.)  It was outlined this week in a paper called “Real-time Distributed MIMO Systems” at the Computing Machinery’s Special Interest Group on Data Communications conference in Brazil.

Wireless Pileup

To understand what happens when radio waves collide, go back to your high school lessons that show them as undulating lines with peaks and valleys.  If two of these lines overlap perfectly, peak-to-peak and valley-to-valley, they boost each other.  If they line up peak-to-valley, they cancel each other out.  Usually, they are at some point in between the two extremes, each warping the other.  The MIT team’s ah-ha moment: If they could anticipate how waves would overlap, they could tweak the signals ahead of time to counteract the warping.  “Now when these modified signals come through the air, they are still going to collide with each other,” says Rahul.  “But after the collision, the signal is now what you want.”


Easier said than done.  In fact, the process requires continuous measurement of the wireless network as it’s disturbed by things like connected laptops and phones moving around or people walking by.  It also requires keeping all the access points in communication to coordinate signal-tweaking efforts.  That rapidly eats up bandwidth until none is left.  “If you are coordinating 16 APs, you would essentially spend all your time exchanging information and never actually have any time to send the data,” says Rahul.  That’s hardly a way to boost performance.

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Number of Australian radio hams fell in 2015

Via Southgate ARC (original post here), via the VK1WIA News broadcast.

This is WIA Director Roger Harrison VK2ZRH with news on licensee numbers and what might be done about attracting new amateurs.

In WIA News Roger VK2ZRH says:

In a recent broadcast, I reported that the total number of individual amateur licensees in 2015 reached 14,144, which is up from 14,035 for 2014.

Well.  I was wrong!

I am informed that the figure of 14,144 individual amateur licensees for 2015, is in fact 13,977.

So – we lost fifty eight amateurs over 2015, compared to 2014, when there were 14,035 licensees.

Marc Hillman VK3OHM, who ran the numbers from the ACMA database for the WIA’s Open Forum Reports published for the AGM in May, has – er – “confessed” to the error.  “I accept all the blame for misleading people”, he said in an email to me.

Marc’s sterling analytical efforts to provide snapshots of amateur licensee numbers over the years are widely appreciated, no less so than by the WIA Board.

I am reminded of a few lines from the Goon Shows’ “Tales of old Dartmoor”.  The Goons take Dartmoor Prison for a sailing holiday to the south of France.  Having discovered that Eccles is responsible for a miscalculation in navigation, Neddy Seagoon berates Eccles, shouting: “You idiot! We’re 4000 miles off-course!”.  Eccles responds with, “Nobody’s perfect…”

Anyway, amid the bad news of 58 licensees lost over 2015, I took a look at 2013 versus 2014.

We had 14,202 licensees in 2013, which fell to 14,035 for 2014. That’s a loss of 167 amateurs.


Can we conclude that the loss is declining because we only lost 58 over 2015?

Well, no. Not until we know what happened over this year.

Naturally, of course, the naysayers out there will blame these losses on the nearest available target – the Institute.

But then. Aren’t we all in this together?

At the regular August WIA Board meeting this past week, the Board agreed to organise a symposium, you might call it a summit, in November, in Canberra, for all those interested or involved in S.T.E.M or S.T.E.A.M activities – Science Technology Engineering Arts and Maths – to plan ways and means the amateur radio community can engage those interested in technical pursuits.

This is one area from which future radio amateurs will likely emerge.

Watch this space.

This has been WIA Director Roger Harrison VK2ZRH for VK1WIA News.

Paul VK2ICQ adds:

Here’s a table from the WIA Directors report showing historical licence numbers back to 2011, as published by the WIA critical ‘WIA Reform Group* in their post ‘WIA board in denial as amateur numbers decrease‘.


*Opinions expressed on the ‘WIA Reform Group’ website do not necessarily reflect the views of the Oxley Region Amateur Radio Club.

Tokyo Ham Fair 2016 Videos

The Tokyo Ham Fair was held on the weekend of the 20th and 21st of August 2016.  Here’s some neat videos of the manufacturer’s booths courtesy of YouTube user JI1ETUjr.  This is the biggest ham fair in the world with around 35,000 visitors (Dayton has around 25,000) – so it should definitely be on your bucket list!

Major highlights include the Icom IC-7610 (still in development, but look at that screen!), IC-R8600, IC-R30, ID-51 Plus2, the Yaesu FT-991A (now with real-time spectrum scope) and the Kenwood TH-D74 (Tri-band Handheld with D-Star and APRS).

Icom Booth

Kenwood Booth

Yaesu Booth


Alinco Booth

AOR Booth

Changes in technology mean consumers need to upgrade


From the WIA, original post here.

Date : 22 / 08 / 2016 
Author : Jim Linton – VK3PC

A warning from Telstra is that the 2G mobile network is to be shut down at the end of November this year.  The telecom company has written to its affected users advising them they need to switch to newer 3G or 4G technology.

Meanwhile, WIA members registered with MEMNET who use PC’s and web browsers which are more than 10 years old such as Internet Explorer 6 or Opera version 5, will need to upgrade as support is being withdrawn for these early browsers.

Sunday the 28th August Omni Software the provider of the WIA’s MEMNET service will be undertaking maintenance works and system improvements to support the latest security protocols, Omni have advised that any users affected by the upgrade will need to upgrade from their old Web browser versions.  They advise that all versions of Chrome, Safari, Firefox, and Internet Explorer 7 and above should be unaffected, although they recommend all users update their browsers to the latest version available.

The WIA apologises for the short notice given but timing of the change is purely in the hands of the MEMNET software provider.

Amateur Radio Sleuthing Pins Down Source of Strange RF Interference

Evanston RFI-2From the ARRL, original post here08/09/2016

Police in Evanston, Illinois, contacted the ARRL Lab, after an apparent interference source began plaguing wireless vehicle key fobs, cell phones, and other wireless electronics.  Key fob owners found they could not open or start their vehicles remotely until their vehicles were towed at least a block away, nor were they able to call for help on their cell phones when problems occurred.  The police turned to ARRL for help after striking out with the FCC, which told them it considered key fob malfunctions a problem for automakers, although the interference was affecting not just key fobs but cell phones, which are a licensed radio service.  ARRL Lab EMC Specialist Mike Gruber, W1MG, believes the FCC should have paid more attention.

“This situation is indicative of what can happen as a result of insufficient FCC enforcement, especially with regard to electrical noise and noncompliant consumer devices,” Gruber said.

Evanston authorities worried that a serious situation could develop if someone were unable to call 911, putting public safety at risk.  They also were concerned that the RFI could be intentional and indicate some nefarious or illegal activity.  Given the seriousness of this situation, Gruber contacted Central Division Director Kermit Carlson, W9XA, to ask if he could look into the matter.

On June 2, Carlson met with an Evanston police officer, her sergeant, a local business owner, and the local alderman, and he quickly confirmed that the 600 block of Dempster Avenue in Evanston was plagued with an odd RFI problem.  Carlson determined that the problem prevailed along a set of eight on-street parallel parking spots in the downtown commercial district of the North Chicago suburb.

Evanston RFI-1

Carlson employed a Radar Engineers 240A Noise Signature Receiver and UHF Yagi antenna to survey the affected block.  Since key fobs typically operate at around 315 MHz and 433 MHz, he looked on both frequencies.  The survey identified several noise sources in the affected block, but in particular a strong signal in the middle of the block.  The interference source turned out to be a recently replaced neon sign switching-mode power supply, which was generating a substantial signal within the on-street parking area just across the sidewalk, between 8 and 40 feet from the sign.

The problematic power supply interference also disabled Carlson’s cell phone when he was within a few feet of the device.  Carlson anticipated that further investigation would show that the harmful interference could disrupt licensed radio services in close proximity.  The troublesome transformer was not replaced, but the building owner agreed to turn off the sign should problems arise.

Carlson called the Evanston case “a particularly alarming example of radio interference,” especially since local authorities considered it a public safety matter.  “This situation demonstrates the electromagnetic compatibility problems that are evolving in an atmosphere of noncompliant, unintentional RF-emitting devices,” he said.

A return visit to the area with calibrated antennas and equipment capable of measuring the radiated signal strength with quasi-peak detection is planned for later this year.  Since the initial visit, several other instances of unexplained key fob malfunctions have been reported in the Greater Chicago area. — Thanks to Kermit Carlson, W9XA, and Mike Gruber, W1MG