It's October again and Munich's Oktoberfest is in full swing. In the tents, 100.000 seats are available to celebrate and mobile networks are challenged by the number of devices per square meter. They seem to hold out quite well though according to these interesting reports (in German, sorry) by Teltarif. But how much of a challenge is the Oktoberfest really to the networks? Let's play a bit with the numbers!
If there are 100.000 seats available in the tents then let's say that at any point in time there are around 150.000 people present, inside and outside of the tents. According to Wikipedia, the Theresienwiese on which the Oktoberfest is celebrated has 31 ha, which is roughly 500 x 500 m. I've put a map on the left to give you an idea of the location's size. 150.000 people packs a place this size quite tightly. If you have a look at the pictures from people taken at the Oktoberfest or on Wikipedia it's obvious the number is not overstated.
The next number that's available from this report is that one of the four network operators has put up 8 additional cell sites for the event and I assume the other network operators have put up similar numbers and the same or different sites. Let's say there are two sectors on each site as some of them must be at the border of the event area and hence the third sector pointing outwards doesn't carry as much traffic. GSM, UMTS and LTE are up and running but GSM doesn't carry a lot of data so I'll leave it out of the game.
Let's say out of those 150.000 people, 100.000 use a smartphone and do so heavily. Tweeting, texting, sending WhatsApp messages, pictures, Facebook, etc. etc. should drive uplink traffic well beyond the normal uplink/downlink ratio. After all, you need to show your friends where you are by sending pictures and they probably interact with you heavily so phones are unlikely to stay in pockets for long. So let's say the mobiles of those 100.000 people are connected to the network once every 3 minutes and stay connected for around 20 seconds. That means that each mobile device is online 60 times per hour for a total of 7 minutes every hour. 60 times an hour is perhaps a bit on the high side for an average, but let's be pessimistic.
Now, let's divide the 100.000 users by 4 network operators so each serves around 25.000 customers. There are 8 cell sites with two sectors each so 25.000 / 16 means each sector of each network operator serves 1562 devices. Each device is on air for 7 minutes per hour which means 208 mobile devices are on the air in each sector of each operator simultaneously. Sounds like quite a lot and if there was only UMTS, it would probably have a hard time, even if each network operator had deployed two carriers. But LTE cells can quite cope with such a number of simultaneous devices. And if the maximum capacity is reached it's possible to deploy extra LTE carriers, e.g. a 2600 MHz low power signal to catch the devices close to the cell and a somewhat higher power 1800 MHz signal to serve devices further away. Add UMTS to the overall mix and I would say there's still a healthy margin to work with.
Obviously the numbers I've used above are only assumptions and could be off by quite a bit. If you have more precise numbers please let me know, I'm happy to adapt my calculations.