I'm trying to work on a prototype wearable indoor and I am really confused as to how I am going to transfer data fetched from the GPS device to the server. Is GSM module the best option or should I go for WiFi? How can this be achieved and what are my best options?
GSM modules or WiFi
gsmwearablewireless
Related Solutions
No, they don't have multiple GSM modules. That would drive up cost, size, weight. Since the user is only on one call or the other, there isn't a need for more than on GSM module.
EDIT Jan 31 '12. Wikipedia says there are phones that can use both at once. But I still believe there is only on GSM module.
If your bandwidth requirements are less than ~230.4 kBaud or so, then the cheapest and easiest way is to use one of the many HC-05 (or similar) serial BT modules available from eBay.
(EDIT - note comment from Chris on iPhones below)
Here's an example (you can also get versions with a pin header for through hole or breadboard use):
They may claim faster speeds, but in my experience with a few of them, the best performance I have had without issue is 230.4 kBaud (of course this may also be due to the paired modules capabilities also, though my module stopped responding to AT commands when set to higher speeds)
If you need better performance (and datasheets) there are also better quality (and more expensive) modules available from the major vendors such as Farnell, Mouser, etc.
Best Answer
If your final product is designed to be worn outside you have to go down the GSM path as it work in a wider range. If it is indoors only Wi-Fi is more appropriate.
The reason is cost. GSM covers a wider range, but it requires a more expensive module, and you also have recurring costs from the cellular carrier and running a publicly accessible server (since you need at least either a static IP address or a domain name, and either of them cost money.) Wi-Fi, however, covers only inside and immediate around the building the access point is set up, but requires only a cheaper module, and since it is, after all, LAN, so there is no recurring cost other than electricity bill (which you also have to pay if you go down the GSM path anyway)