Book Review: All These Worlds

When I finished the second book of the Bobiverse trilogy by Dennis E. Taylor, I immediately jumped into ‘All These Worlds‘, the third and (so far) final part of this brilliant science fiction series. Short summary of what happened so far without too many spoilers: Geek brain gets frozen today, wakes up as replicant a hundred years later, explores the Galaxy and tries to save mankind with the help of his clones. The second book ended with the clear indication that in the third part, Bob and his ‘descendant’ clones would have to deal with ‘the Others’ and that a peaceful solution was probably not in the cards.

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My 5G Intro at GPN19 – In German

Thanks to a public holiday in Germany, I just had a 4 day weekend and spent most of it at GPN19 in Karlsruhe learning new things, meeting people and giving back to the community by holding talks as well. I really like that we have lots of community organized hacking events all year around and this one is a particular fun one. It is not as big as the yearly ‘Congress’ in December but still has a lot of diverse topics to get inspired and 1800 people attending.

One of the talks I gave was  a technology introduction to 5G (in German). Probably too high level for most of you visiting this site regularly but being even more overhyped than 4G a decade ago, I thought it was time to talk about technology and reality rather than myths and marketing fluff. A big thank you to the great C3 Video team, it took them less than 2 hours to publish it!

How To Run A Server At Home Without An IPv4 Address

IPv4 tunnelingOnce upon a time the Internet was bidirectional and everyone could run a server at their end. Unfortunately, these days are long gone and many ISPs today, especially cable providers, do not assign a public IPv4 address to their customers. Not even when you ask them nicely. Not even for money, unless you are a business customer who is willing to pay through the nose for the privilege. Fortunately, there is a way to run servers at home and make them accessible to the outside world and an easy one at that. The following text and shell commands are from a talk I gave at GPN19 (in German).

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5G NR Throughput Calculator

So far I’ve always made a quick and approximate calculation when somebody asked me what the theoretical peak data rate of 5G NR would be for a given bandwidth. But there is a more scientific way to do this as 3GPP has put a formula together to include all relevant factors in the calculation. Using this formula it is then possible to not only calculate the theoretical peak throughput but also what can be achieved in realistic transmission conditions. As the number of parameters that go into the calculation is quite lengthy a number of people have made online calculators available. Here’s a good example.

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Looking Back: The Year I Published My First Website

After trying to remember when I used the Internet for the first time in my previous article on Gopher and the early World Wide Web, and coming to the conclusion that it was in 1994, I’ve then taken the next step and tried to remember when I actually published my first website. So here’s the story.

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LTE RAN Congestion Behavior

Uncongested network througputThings are good in the network when you get downlink and uplink throughput results like in the first screenshot on the left. Downlink speeds are in the 150 Mbit/s range, uplink is in the 50 Mbit/s range and the round trip delay time is around 19 ms. Unfortunately, this is not always the case. I’m a bit disappointed that I sometimes have to discover that in places such as large train stations with thousands of people in close proximity, networks are only on air with a single LTE carrier. No carrier aggregation and no small cell deployment anywhere to be seen.

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Configuring Prosody for iOS and Chatsecure Push

I’m one of those people who run their own XMPP server because I like my privacy. In my case I use Prosody and by default it communicates directly with the client apps such as ‘Conversations’ or ‘Pix-Art Messenger’ on Android. Unfortunately, iOS is much less cooperative and in the name of power saving, cuts the connection to clients a few minutes after they have gone to the background. Sending messages to these clients then requires the use of Apple’s push service to wake up the client app, e.g. the Chatsecure app, so it can pull the message from the server. So how is that done in practice?

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Number of Subscribers per LTE Base Station

Back in 2016 I wrote an article in which I calculated the number of users that are served by an LTE base station site. I made my calculations based on the number of base station sites and subscribers in Germany that are publicly available. My conclusion was that an LTE base station site serves about 750 subscribers. A few days ago I came across this presentation by Nokia given at Aalto university in October 2018 which has interesting numbers on this topic as well.

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Book Review: The Man Behind The Microchip

Book Cover - The Man Behind the MicrochipFurther and further back I go to find out why things in computing today are the way they are. The latest book I have read on computing history is actually a bit away from computing and is about the development about the transistor, microchips and finally, microprocessors. One person that significantly stands out in this story is Robert Noyce and Leslie Berlin’s book ‘The Man Behind The Microchip‘ is a fascinating biography of a man who’s ideas have changed the world in a big way with something very little.

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