Today’s smartphones are rich processing platforms that can easily handle the load of baseband modulation of an M2M satellite waveform that do not support nor require high symbol rates.
The concept is to have a small radio module that connects to a smartphone via Bluetooth. The radio module performs the up/down conversion L-Band transmissions, while an app on the smartphone performs all base-band processing, modulation, receiver synchronization and air interface protocol communications. The app presents a user interface with messaging/chat and status functions or can provide remote control and monitoring for other devices.
The prototype was implemented using the Ettus Research E100 platform. A Bluetooth transport was used for exchange of digital base-band samples. The front-end module performs amplification and duplexing of the L-band RF signals. An off-the-shelf antenna was used for the prototype.
For testing purposes, a network emulator was developed to run on a PC, using a separate USRP platform connected to the prototype. This allows system-level testing of the prototype before on-air trials. Finally, the prototype was tested on-air on a commercial service.