1. Problem Statement
There is a certain kind of livestock (such as horses, mares, some cows, or even sheeps and goats) that in the summer are freed into the mountains and areas of several square kilometers. The thing is that the rancher usually needs to keep some attention into the livestock, for example for some medical reasons, or just because he needs to gather them back because the weather is getting bad. This leads to the rancher having to search with his car along very wide areas, which might mean several hours to find just an animal or a herd.

2. GNSS Solution
The idea they had at Domodis was to add a GNSS (GPS actually for this specific case) to locate the livestock. The problem is of course that GNSS will give the location to the chip, which is attached to the animal, so there is a need to take that data back to the rancher. In order to do this, they use a GSM transceiver that would send an SMS with the data. You can find two operation modes, one in which you make a call to the associated phone number and you automatically receive an SMS with the location, and another that sends every X hours an SMS to a central that process this data and stores it in a database. This second approach is better, as it let you have everything stored and you can even have a track of your livestock which can be useful for the rancher.

3. Limitations
The main limitation is the battery. The good news is that this boxes can be pretty big, so you can install high-capacity batteries, but I read that they still had some problems. The desired minimum lifetime would be 3 months (for the summer). Using the second approach is better in the sense that you can have a low-power circuit that awakens every X hours and activates the GNSS receiver and the GSM. 

4. Possible optimizations
- This technology is nowadays not so developed, and you can see that the boxes they sell are just some systems put together, there is nothing as an IC design or anything, so I'm sure that if there was money on it the battery could last far more time than nowadays.
- Nowadays they're using it just to know the location (and the %battery) but this could be use to send more data with some additional sensors. Some basic monitoring could be perform to the animal, for example if it is ill.