7 Days, 15 Terabytes and 1 Kernel Bug Later was the headline of a post back in March this year in which I described how I was chasing a problem with file read and write performance that got worse the more RAM I put into my notebook. With 16 GB of RAM, file write speeds deteriorated after only a few gigabytes and I finally chased down the issue to a kernel bug. Fortunately, after upgrading from Ubuntu 14.04 with a 32-bit 3.13 kernel to Ubuntu 16.04 with a 64-bit 4.4 kernel the problem went away. In addition, file read and write behavior has changed completely
Beware of GSM Service On Board of Aircraft
When I recently flew from Europe to India with Lufthansa I was quite happy to have Wifi on board. For 17 Euros I could get access to the Internet for the complete flight. Not cheap but if you take the ticket price into account it’s acceptable. Like on this flight earlier in the year, connectivity was somewhat slow and patchy but good enough for many things. In addition, this plane was also equipped with a GSM cell. What sounds cool at first turns out to be a massive money trap if your are not careful.
Prime Use For UMTS Fast Dormancy Today: Fast Reselection to LTE
Just a quick thought today about a use case change of a feature over which hard battles were fought about in the past: UMTS Fast Dormancy.
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Eduroam Setup For Ubuntu 16.04
Eduroam is a great Wi-Fi network setup for students. With certificate based authentication, setting it up securely is a bit of a hassle. Once done, however, one benefits from a per device Wi-Fi encryption key and international roaming capabilities. I very much like the system and have described my experiences here and here. For Ubuntu 16.04 and later, however, the security configuration has changed and one has to be careful as there is no security warning if an old setup is reused. Read on for the details.
A COW in New York
When I was recently at Times Square in New York I noticed an interesting looking trailer: A Cell on Wheels (COW). Either a network operator had a problem with one of its permanent base stations or they needed some extra coverage for a live concert in progress at the time at one of New York’s busiest places..
20 MHz in Manhattan – I’m Surprised
With a few hours to spend before flying back to Europe, I went to New York’s impressive public library for inspiration and contemplation. While I was there I also ran a quick trace of how much spectrum is in use for LTE by network operators in the area.
LTE Air Interface DRX Settings in Practice
In a previous post I’ve given an introduction to how LTE Discontinuous Reception (DRX) for power saving works in theory and which parameters can be configured by the network in practice. In this post I have put together a number of typical configurations I have seen in practice from Portugal, Spain, France, Germany and the US.
LTE DRX – A Bit Of Theory Before We Look How It’s Done In Practice
I recently noticed that LTE power saving settings are significantly different across different networks in different countries. Before sharing this info I thought it would be good to have a quick overview post of how LTE power saving works and which main parameters the network can configure.
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The LTE Band Challenge – 5 Years Later
5 years ago, when LTE was just about to hit the real world, I wrote a blog post about the LTE band challenge. Even at the time, 3GPP defined more bands for LTE use that one could count with two hands and even more have been added since. It was quite worrying 5 years ago when the state of the art in mobile devices was to support 4 GSM bands and 2 UMTS bands. Fortunately the situation has much improved since then.
How To Make Use of the 1400 MHz Band for LTE In Europe
Last year two network operators in Germany have each won 20 MHz spectrum in the new 1400 MHz band. The interesting thing about that piece of spectrum was that it’s uni-directional, i.e. it can only be used for downlink-only transmission or, theoretically, also for TD-LTE. At the time it wasn’t quite clear to me how the spectrum is going to be used. In the meantime, however, 3GPP has defined how to use the band.
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