Why does the data transfer occur over WiFi?

We considered a number of approaches for transferring the encrypted data files from the computer to the iPhone.  WiFi is the best option.  The other approaches we considered are:

1) Bluetooth: Bluetooth on the iPhone is only usable for headsets as far as we know. Apple doesn’t expose Bluetooth in its supported iPhone APIs.

2) USB wired transfer:  Apple also doesn’t officially support iPhone file system access over USB.

3) We also considered wireless through the cell network, however we did not think this was a viable solution because:

  • Cost to the customer. Depending on the carrier and plan, the cost of downloading several megabytes a day could be significant.
  • Requires a world-accessible server. The data must be exposed to the Net. This raises all the usual challenges related to constructing and operating a world-accessible data server in a school.
  • Possible performance constraints. Significantly slower than WiFi. Depending on carrier and location, may be drastically slower than WiFi.
  • Not available on the iPod touch.