Headworx

The "proper" Internet routing protocols are based on a concept of a "next hop" address. When a packet arrives at a router, it takes the destination address and based on the routing table determines the address of "the next hop" the packet should be sent to. And forwards it to this next hop router. This works reasonably well when the routes are not changing frequently. And when the next hop is available most of the time. What seems weird, some wireless architects try to apply this concept to low power wireless networks, where the routes do change frequently (wireless nodes have freedom to roam around) and availability of the next hop is not given. Wireless networks change topology not only due to the nodes physically moving, but also due to the noise floor of the channels fluctuating continuously. A node within 60dB (path loss) range is usually available (but this is just a couple of meters), but a node 90dB away may be falling down to be 110dB away jus...

I keep investigating the power drain experienced on my Blackberry Priv phone. And actually I'm getting some consistent results. The screenshots are taken at the end of days that were very similar from the phone usage perspective. And the one on the right has 50% more juice left. The first option that helps running longer is disabling 4G/ LTE in the Cellular networks menu. Clearly when switch to HSPA+/UMTS/GSM helps while still giving very decent mobile data performance. The second option, with results illustrated by the attached screenshots, is one I have almost entirely forgotten about. It is the Physical Web in Google Chrome. It is off by default so most people are not affected. I turned it on months ago and then simply forgot about its existence. It does very little but means a lot to the beacon industry, as it is meant to resolve signals from Bluetooth beacons into useful content links. It runs in a background continuously scanning for Bluetooth advertising packets. I am ...

Last week I posted on the airline industry racing for newly designed aircraft built of new composite materials to shave hundreds of tonnes of weight that do not have to be kept airborne. This is pure physics that dictates technology choices when designing a well performing airliner. Steel and aluminum are the two most popular materials used in ground and sea transportation today: cars, trucks, railroads, trains, ships. But you simply cannot use steel and even using aluminum becomes less of an option today when building an airliner. The same is true when trying to take technologies used in wired communication networks and apply them to wireless networks. This just does not work, because the physics of electromagnetic radiation in radio frequencies are fundamentally different from the physics of a copper wire or of a strand of glass. Fundamentally it starts with wireless being much more lossy, due to interference. Smartscrapers surround us. The density of wireless IoT radios toda...

Quite often I keep asking myself: "how do we really measure progress?". And in some remarkable cases the answer is very precise. Like in the aviation industry: in tons per year. Lufthansa has begun phasing out the A340-600 jets. Two weeks ago I saw a number of them sitting by a service hangar in Munich. And some have already made their farewell flights to Arizona . I remember - it must have been around 2002 when the 4-engine jet came into service. So exactly 15 years have passed and we now have the new queen of the sky - the A350. A350 is identical to A340-600: 300 passengers, 12000km range. With the one striking difference: it weighs 100 tonnes less. Which is incredible, considering this thing is design to float in the air. So if it is capable of carrying the same load for the same distance and has managed to shave 100 tonnes of ballast, imagine what it does to fuel efficiency. It is like not having to carry this weight across an ocean...! 100 tonnes in 15 years is a...

Computer upgrade used to be a fairly traumatic experience. Especially on a Windows machine (I don't have too much experience with OS X) it usually meant many hours of re-installing applications and re-configuring drivers for all peripherals such as printers. And only recently I realized it no longer has to be. A simple method we decided to try when upgrading my son's machine. He was using a 2010 Mac Mini running Windows 10 on an upgraded SSD drive. The Mac itself still performs very well, but the graphics performance - never a strong feature of Macs - has been absolutely inadequate to run most of 2017' games. Weighing his budget carefully he found an option to buy a 17-inch refurbished Lenovo Y-700. A beast of a laptop. Refurbished meant "no operating system included" - but we figured out the license of his Windows 10 copy running on the Mac was perfectly adequate to run on the new machine. After pre-allocating a whole day for the migration process we care...

In November last year the battery life of my Blackberry Priv started deteriorating rapidly. I could barely survive a day on a charge and it was getting worse. I got used to recharging it mid-day. Desperately looking for a replacement battery (still have not found one) and possibly another reason that might have been the root of the problem. I knew I could try to factory reset the device but during that busy time I just could not afford spending a couple of hours reinstalling all the apps. And then magically on January 15th the heavy drain stopped. You can see it on the burndown charts. One shows the phone barely lasts 6 hours the other shows it can comfortably live for 27 hours. Barely a 450% difference. The worst thing is I can not figure out what was the reason. It behaves now like it used to a year ago. Unfortunately the Android battery diagnostics do not help much. I suspect the reason may be the LTE (4G) option. Desperately looking for a way to minimize the drain it has...

Reliable communications is challenging. Even more when it is wireless. The roots of the problem are interference and collisions, collectively known as noise. When a radio packet travels through air it very likely meets other packets. Or other forms of electromagnetic waves. Interferes with them and collides and may become so distorted that a receiver will not recognize it. And the message does not get through. Some systems implement so called reliable delivery mode. The principle is simple: request a confirmation message from the destination. If it does not arrive, try again. And again. This works but is not always effective. First, it increases the number of packets in the air, so they may cause new collisions with other packets. Then it introduces delays and even more noise. Before a next delivery attempt you need to give the network enough time to deliver the message back and forth. And the intermediate relaying nodes to process the messages and the recipient to execute the comm...