Ways to communicate GPS coordinates to a central server wirelessly from a wearable device

Question

I am currently looking at designing a wearable device for a client, which can communicate GPS coordinates back to some sort of central server (to then be sent out to other communicating devices such as mobile phones). The area of the tracking system would be known, and would be a confined space (let's say within a 3 mile radius).

I have no experience in this field and want to know the different options available for sending the GPS coordinates out from the device. The way I see it there are 2 options (that I know about):

• Use mobile networks and some sort of SIM card to communicate the coordinates back
• Use a local WIFI network and some sort of wireless communicator in the device

There may be other types of hardware that I know nothing about, hence why I have asked this question on here to get a bit of advice.

Answer 1

There's the so-called "ISM" bands, 900MHz and 433MHz. And there are Nordic Semiconductor devices which use a proprietary protocol in the 2.4GHz band. All of these are capable of moderate range in the open with suitable modulation and data rates.

Answer 2

Another method is to have your wearable talk over Bluetooth (BLE) to a head unit (often a cellphone) which acts as both the GPS and the uplink. One benefit is that the cellphone can switch between Wifi and GSM, and allows the user control over how the data is uploaded.

If you design with a custom GSM solution, look at Internet of Things (IoT) and Machine to Machine (M2M) plans from your cellphone provider. These differ from regular cellphone plans and are better suited to the usage required of embedded devices (data w/o voice, greater data caps, etc).