An open digital interface between SDR baseband processors and RF

摘要

The following document presents an open, digital interface -OpenIF - designed by RadioScape Ltd., which enables high speed control and user data to be sent between front-end, RF processing units, and backend, generic signal processing components, for use within basestation, test and prototyping products. The adoption of such an interface is central to the success of software defined radio (SDR), both as a design-time and run-time technology, as it enables the production of analogue/RF components independently from the digital domain hardware and software. OpenIF utilises the User Datagram Protocol over IP (UDPI'P) to carry information. The configuration of RF hardware is realised using the Simple Network Management Protocol (SNMP), as many different technical specifications can be represented as a standard set of messages (e.g. Power Amplifier (PA) ramping, frequency tuning, etc.) coupled with a small set of application specific messages built from the standard set. Because the interface is open and extensible, the overall system architecture need not be changed when processing different communications or broadcast standards. The interface is decoupled from any underlying physical layer (although a particular variant, LVDS, is described here). RadioScape has used the OpenIF interface in its generic baseband processor (GBP) platform, a FPGA/DSP substrate for high-bandwidth digital processing. Having found the interface extremely useful internally, we present it here for consideration by the rest of the industry. This paper aims to give the reader a broad overview of the OpenIF interface and is not a standardisation document or proposal.