Author: Martin

Local network technologies like WLAN have a distributed coordination function, i.e. every device decides for itself when it wants to transmit on a common channel and have backoff and repetition features with random and increasing delays to get out of situations when more than one device transmits at the same time. Another helpful thing in local networks is that there are usually just a limited number of devices so distributing control instead of having a centralized controller usually works well. In cellular networks, things are quite a bit different and sometimes mobile devices don’t act very friendly when their communication request is rejected and start bombarding the network with connection requests that are promptly rejected again if the reason for rejecting them persists. Especially in the world of IoT, unfriendly devices can become a problem quite quickly. Time to do something about that…

Continue reading Cellular IoT – Network Friendly Devices and GSMA TS.34

Another book I recently read about the history of computing is “When Computing Got Personal” by Matt Nicholson. It took me quite a bit to get around to this one because its approach is more holistic than the books I have read before about specific events of companies. Also it’s not as ‘Valley’ centric than the others so perhaps it has a bit less appeal to get picked up. Not so its content, however.

Continue reading Book Review – When Computing Got Personal

So far I was really wondering why the industry is doing 5G in the first place for frequency bands below 5 GHz and why a new core network architecture is required and useful!? At last I have now found one interesting answer for the core network side: Let’s revamp security and privacy and make it much better!

Continue reading Encrypted IMSIs in 5G

Today another post in my popular series on historical computing. When the Busch 2090 microcomputer learning kit came out in 1981 it required the user to write programs on paper, translate the instructions to machine code and to calculate memory addresses and branch destinations himself. In an iterative development process this is more than just a bit painful as memory addresses of branch destinations change all the time as instructions are added and removed. Now that I’ve put my Busch 2090 tape emulator to good use I decided I needed an Assembler that does these things for me. As none exists so far, I decided to program one myself.

Continue reading An Assembler for the Busch 2090

15 years ago back in 2002, Linux Torvalds wrote his auto-biography together with David Diamond and the book has been on my reading list for quite some time now. Recently I finally got around to it.

Written back in 2002, the book itself is now a historical artifact and it’s interesting to read it from a 2017 perspective when, compared to back then, Linux seems to have grown into almost any electronic device that has more than a few transistors inside. But even back then, Linus already predicted that Linux will be in mobile phones. I guess not many people could imagine that in 2002. Also at the time, the Linux kernel was ‘just’ 10 years old and still very different from what it is today.

Continue reading Book Review – Just For Fun – Linus Torvalds Auto-Biography

After being very happy in my previous post on EU Roam Like Home coming into effect this is the follow up to take a look at the fine print. Back in September last year I analyzed the suggestions made by network operators of how to ensure that a subscription (pre-paid and contract) bought in one country is not permanently used in another to circumvent different pricing structures due to business models and network build-outs. The suggestions made then would have been quite limiting for my usage scenarios. Fortunately, however, things have changed somewhat in the meantime.

Continue reading EU Roam Like Home – Data Limits

CyanogenMod is history, LineageOS is the new kid in town. So far, however, I’ve shied away from upgrading my Samsung S5, and to tell the truth, I didn’t even upgrade Android 5 to 6 while CyanogenMod still existed. To high the pain for too little gain. But now Android 7 is the mainstream and the platform gets hit regularly by security issues that need to be patched to stay on the save side. No excuses anymore. So one day I decided to bite the bullet and to update by starting from scratch and do a few things differently this time. Little pain would have been involved if I had done the straight forward thing. However,  since I installed from scratch I wanted to get a more secure and private setup. That proved to be much more difficult than I thought and I’m afraid I did not quite succeed with everything.

Continue reading LineageOS on a Samsung Galaxy S5

5 years ago I wrote an obituary on the Thalys train on-board Wifi system. After a brilliant start in 2007 the system was working well for a while before it more and more became unusable. Fortunately, while cellular coverage on the German part along the tracks was and still is lousy, mobile network operators in Belgium and France set up 3G and later LTE coverage close to the tracks. As a result I stopped using on-board connectivity and rather connected to the outside network which works well even at speeds of 300 km/h. When I recently took a trip to Paris, however, I noticed that Thalys has started advertising a ‘new and improved’ on-board Internet and that the classic satellites domes on the top of the trains are gone. So I gave it another try to see if things had really changed.

Continue reading Thalys Improves On-Board Internet Access – Somewhat

Today, 15 June 2017, is the day ‘EU Roam Like Home’ has come into effect. While my personal contract has had an EU option with additional benefits for quite some time now, we have a number of additional SIM cards in the family we use on a daily basis when we travel to different countries. So far, data roaming on those SIMs was simply switched off. Also, we use these SIM cards so people in other countries can call us when we are not in the country. With roaming now being included it was time to flip the data roaming switch on. Also I had to make some changes as one network operator we have a SIM card from is refusing to play along the EU rules. No money from us anymore…

Continue reading EU Roam Like Home Has Started Today – And I Have Flipped The Switches

After having found out how I can make my vintage 1981 Busch 2090 microcomputer board output a program from memory to the 2095 cassette interface board I was hoping that the knowledge I had gained during the process would help me to reach my ultimate project goal which was to  send a 2090 program from a Raspberry Pi via its GPIO ports to the original microprocessor board so I can execute it there. At the beginning it looked like a straight forward process but one thing kept me on the edge for quite a while.

Continue reading Emulating a Busch 2090 Tape Interface – Part 2