Month: September 2018

I recently came across this paper of Huawei on 5G Spectrum matters and one paragraph in particular caught my attention:

“[…] inter-operator synchronisation and alignment of uplink/downlink transmissions (slot and frame synchronization) is […] necessary for efficient deployment of 5G NR networks in unpaired assignments.”

In other words this sentence says that network operators using adjacent spectrum have to synchronize their radio networks to avoid interference. So why is this necessary and what exactly does that mean?

Continue reading 5G TDD: Synchronization Across Networks Required?

Remember the days when you traveled in Europe and had to pay high prices for voice and data roaming as soon as you crossed a border or had to buy a local SIM card for reasonably priced mobile Internet access? It seems like those days are long gone but that’s actually not the case, free roaming in the EU only came into effect last year. And even worse, there are still places on mainland Europe apart from Switzerland that are not part of the EU, where one gets a bitter reminder of how things were in the past. An interesting example is Monaco.

Continue reading Roaming In Monaco

Interested in the past, present and the future of microprocessors? If so, the video of Sophie Wilson talking about the ‘Future of Microprocessors’ at Juliacon is a must see! In case the name Sophie Wilson doesn’t ring any bells, have a look at what Wikipedia says about her.

Her presentation will not only tell you about the history of microprocessors but also why performance hasn’t really increased in the past years, the reasons behind this and why the price per transistor on a chip has started increasing again with further miniaturization instead of further decreasing, which has fueled Moore’s law for the past decades. And most important she will give her educated opinion on where we will go from here.

A few days ago, there’s been a great talk about G.Fast at the Local Chaos Computer Club chapter (C4, Cologne) by Stefan Förster of NetCologne. Here’s a link to the video of the talk (in German). I was particularly interested, because NetCologne recently announced that they have finished their G.fast trial (using the existing telephony copper wiring in buildings) and are about to start commercial service. This sounds like great news and I had quite a number of questions in my mind, including how G.fast can coexist with VDSL Vectoring that the the national incumbent offers in Cologne today.

Continue reading VDSL and G.Fast Coexistence

One thing that I think borders on modern (digital) piracy are the charges for data roaming on board of (some) ships. Cellular on-board networks are often connected via satellite and typically, 1 MB of data transfer, which is barely enough to load the front page of a web site these days, is charged in steps 1 euro per 50 kb. In other words, a single web page costs 20 euros to download. No sane being on this planet would ever want to do that so I assume that 99.9% of the revenues generated that way are from people who’s mobile automatically registered to the on-board network when it looses contact to the land based network for a while.

Continue reading Telefonica Germany Blocks Data Roaming On Ships

Why would anyone ever need then 640k of RAM? How could one ever fill a terabyte disk? There are orders of magnitude between those questions but both limits were easily surpassed just a few years after those questions have been asked. At the moment, a user of one of the computers I administer is approaching the second limit and I am not so sure my attempts of preventive persuasion to move some data to another disk is having the desired effect. So what happens when the disk that holds the user’s directory becomes full? Will programs just freeze? Will the computer still boot? Will suspend/resume still work? Will the user still be able to logon? Will the world come to an end?

Continue reading What Happens When a User Runs Out Of Disk Space On Ubuntu?

I recently took an overnight trip on a ferry from Gothenburg, Sweden to Kiel, Germany. While they were advertising free Wifi on board, which, not to my surprise, totally failed during the trip, I was looking forward to finding out, if and when I could reach the land based LTE network and get connected. As the ship ventured quite far from land, I wasn’t very hopeful that things would work well.

Continue reading LTE at Sea

After the line of my neighbor has been switched to a different port in the street side DSLAM and mine followed a couple of days later, I finally have a stable DSL line again. There are many factors influencing the maximum uplink and downlink speed that can be achieved over a copper wire and since I’m pretty much as far away from the DSLAM as is possible in the center of Cologne, I think my line characteristics and performance gives interesting insights of what’s possible in densely populated areas.

Continue reading DSL, Vectoring and Line Length