WirelessMoves

Earlier this year when I was on vacation in the Austrian alps, I noticed an interesting Wi-Fi behavior that I thought I should note down here for future reference: The impact of a handover from one Wi-Fi access point to another in a distributed system.

I’m a bit of a fanboy of the Apollo moon program of the 1960s, so a recent post by Nick comparing the computing power of a typical SIM card today with the Apollo Guidance computer of the 1960 definitely sparked my interest!

Half a year ago, I decided to retire my car I had for 22 years and not to buy a new one. As I live in Cologne in Germany, I don’t need a car to get around in the city, but suddenly not having a car was something quite unfamiliar. So how does the situation look like half a year later?

These days, I’d say that the majority of underground metros do have 4G and 5G network coverage. There are a few inglorious cities that haven’t gotten their act together for years now, but let’s not talk about them today. Let’s rather talk about the positive examples, i.e. those metros that have gone the next step.

I’m sure you’ve heard the typical ‘GSM sound’ on an FM radio by chance when a phone call comes in and the phone was close to a radio. It doesn’t happen that much anymore of course, as devices are mostly camping on LTE and 5G networks these days. But if you manually select GSM, you can still hear it today. So I was wondering if I could also ‘hear’ Iridium uplink transmissions of my Garmin InReach Mini 2 on the radio?

Recently, two federal states in Germany tested their EU-Alerting System implementation. Based on the cell broadcast mechanism that exists in all 3GPP network technologies since the the days of GSM, it makes phones emit a loud warning signal and shows a message on the screen. It definitely does wake one up, as I already discovered in 2016 in the Netherlands when they had one of their regular test runs of their system.

So while one is inclined to confirm and thus silence the alert as quickly as possible, I wondered if it would eventually stop on its own. Why? Well, every now and then I do have a phone lying around at home while I’m not there. It would be pretty unfair to the neighbors if it kept alerting indefinitely. So I collected a number of different phones and didn’t touch them once the alerts got going. And indeed, after 5 minutes, they all dropped silent simultaneously. Good for the neighbors!

In our household we mostly use Ionos (formerly 1&1) for forwarding our email correspondence. While I personally had little to no issues so far with dropped emails due to spam filters of Google, Microsoft, etc., other members of the household were not so lucky recently. The main problem of emails erroneously dropped by spam filters is that there is no way of knowing that this has happened until people tell you that they haven’t received an email. Since I’m not affected, I was wondering why it happened to other family members recently more than once, and what could potentially be done about it.