My First Prepaid LTE Experience

It's taken a long time and still today, at least in Germany, most network operators reserve their LTE networks for their postpaid customers. In recent months, this has somewhat changed in Germany with the fourth network operator also starting LTE operations and allowing their prepaid customers access from day one. These days their LTE network is also available in Cologne so I had to take a closer look, of course with a prepaid SIM and a €2 per 24 hours data option that gave me up to 1 GB of unthrottled data.

Data rates I could achieve were not stellar but not really bad either. Under very good signal conditions I got close to 30 Mbit/s in the downlink direction and about 10 Mbit/s in the uplink direction. Closer examination revealed that they are using a 10 MHz carrier in the 1800 MHz band which should allow, under very ideal conditions up to 75 Mibt/s in the downlink direction (have a look here if you'd like to know how you can find out which band and bandwidth your LTE network operators is using). But no matter what I did and where I went in the city, the 30 Mbit/s was the magical limit. I don't think the air interface is the limit, the bottleneck must be somewhere else. Under other circumstances I would probably be ecstatic about such speeds but with data rates of 100 Mbit/s+ other operators achieve easily, the 30 Mbit/s pale in comparison.

In a recent network test I reported on, CS-Fallback Voice Call establishment times of that network operator were reported to be pretty bad. I can't confirm this, however, so perhaps they have changed something in their network in the meantime. What's a bit unfortunate, however, is that after a voice call the mobile stays in 2G or 3G a long time before returning to LTE. Other network operators are more advanced and redirect their mobiles back to LTE after the call. That makes for a much better experience. Also, I noticed that there's a 2-3 seconds interruption in the data traffic while switching from UMTS and LTE. That means that they must still be using a rather crude LTE Release with Redirect to UMTS procedure rather than a much smoother PS handover.

While the above is perhaps still excusable, there's one thing they should have a look at quickly: Whenever the mobile switches from 2G or 3G back to LTE the PDP context is lost. In other words, I always get a new IP address when that happens which kills, for example, my VPN tunnel every time it happens. Quite nasty and that's definitely a network bug. Please fix!

In summary the network speed is not stellar compared to what others offer today and some quirks in the network still have to be fixed. On the other hand, however, you can pick up a prepaid SIM in a supermarket and get LTE connectivity without a contract.