5G NR in 3.x GHz – Up- and Downlink Configuration

Network operators in a lot of countries around the world are getting ready at the moment to launch first 5G networks in the 3.x GHz spectrum (i.e. 3GPP band n78). One of the particularly interesting things about this band is that its made for TDD operation and not FDD as most operators are used to. This means the downlink and uplink are on the same channel and separated in time and not on the frequency axis. So how does the network inform the device about when to expect downlink and uplink transmission of the channel in general (not individual reception or transmission opportunities)?

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How To Test New Cellular Stuff in the Wild?

Having a lab as a network operator is a great thing. You can test new hardware and software there and once you are happy you can deploy things in the wild and make things better for your subscribers. But every now and then something comes along that you don’t only want to test in the lab but you actually want to have a proper shakedown to test stability and functionality before you let your subscribers use the new technology. So how can this actually be done in practice?

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A Refurbished Lenovo X250 As My ‘New’ Notebook

For 3 years, I’ve used a refurbished Lenovo X230 as my main notebook. During those years I’ve changed the disk drive several times, first to a 512 GB SSD, then to a 1 TB SSD and finally to 2 TB SSD. Also, I upgraded the RAM to 16 GB as I make heavy use of Virtual Machines and I even exchanged the display panel when it started to malfunction about a year ago. But the frame is now around 6 years old and the replacement IPS panel from China was starting to show a number of brighter patches  that kept growing so it was time to do something about it.

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Some Eduroam Networks Now Use Root Certificates

And today another quick post on Eduroam, the federated Internet access authentication solution for students and researchers.

When I recently noticed that one of the certificates in the certificate chain I put together for an Austrian Eduroam user I support would expire early next year, I set out to do some preventive maintenance and put together a new chain. Quite to my surprise it seems to be no longer necessary!

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Fiber Speeds in Paris – 4 Years Later

Time flies and I can hardly believe that I’ve had a fiber connection at my Paris flat for 4 years now and that fiber is still almost nowhere to be seen in Germany. O.k. I do have vectored VDSL and 100 Mbit/s down, 40 Mbit/s up is not so bad. But fiber is playing in an entirely different league. When I got my fiber Line in Paris four years ago, I measured 264 Mbit/s in the downlink direction and 48 Mbit/s in the uplink direction. So how are things today, i.e. 4 years down the road?

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Further Backup Strategy Improvements

One of my hobbies is to make sure to have a good backup strategy and to loose as little data as possible once the inevitable happens. Rsync and Luckybackup, a graphical frontend for rsync have been my friends for years and helped me to maintain identical copies of critical installations over the years. One weak spot in my backup strategy so far was that some devices are often out of the house and thus away from backup drives and emergency spare duplicates for weeks on end, so any loss of them would mean a significant loss of data. But I’ve got a solution for that, too, now!

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