In-band Signaling
The goal of in-band signaling in the USRP is to support precision timing, TDMA, packet processing, and other related items. The in-band signaling allows for metadata and control information to be sent on the same channel as the data. This information can be used to control the USRP on a per-packet basis, allowing low-latency transmission control which is needed for detailed Media Access Control (MAC) protocols.
Changes Required
To support in-band signaling, several changes need to be made to the USRP as well as the GNU Radio framework.
USRP Changes
- FPGA: modifications to the receive/transmit chains
- USB FX2 Microcontroller: tweaks to the FX2 firmware
GNU Radio Changes
- m-block: addition of the message-block
- Scheduler: support for quasi-real-time hierarchical scheduler
- USRP Class: modifications to the base USRP class
