Software Defined Radio: Baseband Technologies for 3G Handsets and Basestations

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FPGAs: A Platform-Based Approach to Software Radios

Chris Dick and Jim Hwang

Xilinx, Inc., San Jose, CA and fred karris San Diego State University, CA

This chapter provides an overview of the field programmable gate array (FPGA) configured as a real-time signal processor for use in software defined radio (SDR) systems. We focus on signal processing requirements in the physical layer (PHY), which are particularly instructive for gaining insight into the computational power and suitability of FPGA technologies. While there are many complex aspects to a SDR, for example waveform management using the software communication architecture (SCA) and system interoperability based on CORBA, the PHY of an advanced radio system presents significant implementation challenges – and this is an area where FPGAs are frequently employed in configurable radios with great success.

We provide an overview of FPGA device architecture, highlighting features of interest to the signal processing practitioner. We then examine state-of-the-art design methodologies for realizing FPGA signal processing systems and present three representative examples of functions implemented in a SDR PHY: digital down conversion, radio spectrum channelization, and adaptive equalization for a quadrature amplitude modulation (QAM) receiver.

10.1. The FPGA as Signal Processor

To date, the traditional technology choices for real-time signal processing have been DSP microprocessors, ASSPs (application specific standard parts) ...