Category: Uncategorized

I recently wanted to dive a bit into how Bluetooth Low Energy, also referred to as BLE or Bluetooth Smart, works on the inside. One thing that is really helpful after looking at a lot of documentation and great resources on the web is to have a look at an actual trace. There are quite a number of good tools out there to make Wireshark traces but unfortunately it’s quite difficult to find downloadable BLE pcap files. Time to change this!

Continue reading A Bluetooth Low Energy (BLE) Wireshark Trace

TD-LTE is used extensively in China (China Mobile) and Sprint in the US today. In Europe, there are only few deployments so far and I haven’t come across one until recently when I was in Stockholm. And again, there was more deployed than I initially thought!

Continue reading LTE in Sweden – Part 3 – TD-LTE in Stockholm

When it comes to file access over the Internet, Windows Shares (SMB) are a no-go as file transfers are not encrypted and the ports used by the protocol are often blocked by Internet providers. Webdav shares are often also not practical. Therefore I’ve used SCP in the past on the command line to transfer individual files from any place in the remote file system. The problem with this is that for many tasks the command line is way to cumbersome to use. But did you know that the Ubuntu file explorer can use SSH/SCP/SFTP to connect to a remote file system and bind it locally? Continue reading Ubuntu And SSH File Access In the File Explorer

In a previous post I’ve taken a look at the current deployment of LTE in a more rural area of Sweden south of Göteborg. One of the interesting things I found there was that Telenor used 10 MHz in the 900 MHz band for LTE while only the remaining 5 MHz was used for GSM. At the time I expected that perhaps in a more urban area things might be different as there might still be more need for GSM when there are more people. So I had another look in Stockholm.

Continue reading LTE In Sweden – Part 2 – Stockholm

Ever since I discovered the use of a TV in hotel rooms for streaming videos or its use as a second screen almost a decade ago, I’m always taking a DVI/HDMI cable along when I travel. These days, however, TVs in hotel rooms are getting larger and larger. While this is great news for video streaming from the PC, they become less and less useful as a second screen for work. But recently I’ve found a great alternative: Portable USB screens.

Continue reading Ubuntu And A USB Attached Screen While Traveling

There are a number of devices and network operators out in the wild now which do not only support Voice over LTE (VoLTE) but also Voice over Wifi (VoWifi) and can even hand-over ongoing calls between the two radio access networks. But there is one thing: Which RAN should be preferred if both LTE and Wifi are available? The answer is not as simple as it looks at first.

Continue reading Voice over Wifi – Which RAN to Prefer?

I’ve been in Sweden for a couple of days recently, around 30 km outside of Göteborg in a pretty rural area. Obviously I did not only enjoy the beautiful landscape but also had a closer look at what is on air in this region. I was quite surprised about what I found as GSM is definitely on the way out here.

Continue reading LTE in Sweden – Bye Bye GSM (Almost)

When GSM was designed, the network and the voice service running over it were inseparable. That’s because the GSM network was designed in the 1980s as a mobile voice network. Fast forward 20 years and the picture had changed significantly with LTE having been designed as a wireless network that only transports IP packets. Agreed, it took another 10 years before Voice over LTE (VoLTE) was ready to replace the CS-fallback (to GSM and UMTS) mechanism for voice telephony. Now Voice over Wifi that is deployed by first network operators shows that VoLTE really is network independent. Continue reading VoLTE and VoWifi – Wireless Telephony Has Truly Become Network Independent

When I recently wanted to find out which network operators have which and how much spectrum assigned in a country I found an incredibly cool website that has up to date information on this topic. Have a look over at spectrummonitoring.com! Not included in the charts is the US, probably because in this part of the world spectrum assignments vary quite significantly even between cities. But for Europe, Asia and the Americas a huge number of countries are present on the site.

Even if you have a VoLTE capable phone and use it in a VoLTE capable home network, chances are that when push comes to shove and you have to make an emergency call, it’s not done over VoLTE. Instead, CS-Fallback is used to establish the emergency call in GSM or UMTS. But at some point, network operators will likely retrofit their VoLTE installations to be also able to handle emergency calls. I recently wanted to have a closer look and found an interesting resource on the web that saved me a lot of time.

Continue reading VoLTE – Some Thoughts On Emergency Calls