Software Defined Radio 長庚電機通訊組 碩一 張晉銓 指導教授 : 黃文傑博士

Outline Digital Hardware Choices Hardware Elements DSP Processor Field Programmable Gate Arrays Trade-Offs in DSP, FPGA and ASIC

Digital Hardware Choices Flexibility Flexibility-Overall system clock rate be adjustable in different data rate Modularity Modularity-allow easy replacement or upgrading of subsystem Scalability Scalability allow the radio to be enhance to improve capability (increase channels) Performance Performance Power consumption, cost,computational capability metrics

Hardware Elements DSPs: DSPs: microprocessor-based, support high level languages like C, offer the most flexibility ASICs ASICs :circuit in fixed silicon,optimized speed and power consumption, requires sophisticated circuit design and layout software tools. FPGAs FPGAs: provide much hardware-level reconfigu- rability, flexibility: DSP>FPGA>ASIC. Tools for FPGA are similar to those for ASIC Trade Trade: flexibility, processing speed and power consumption

DSP Processor Digital Signal Processors ， DSPs are designed to include special functional units in the hardware as well as special instruction in the microcode FFT or Viterbi decoding Consists arithmetic logic unit (ALU), accumulator MAC unit and data and address buses For wireline and wireless communication,or general control application

Categories of general available DSPs

DSP Architecture Harvard Architecture Program memory and data memory On-chip or off-chip memory Uniscalar Architecture More than one multiplier and ALU Execution of one instruction per cycle Single Instruction Multiple Data (SIMD) Very Long Instruction Word Architecture Superscalar Architecture Hybrid Architectures

Harvard Architecture

Numeric Representation Fixed Point Less power and cost Floating Point Easy to program than fixed point DSP

Pipelining Pipelining is setting up and executing in parallel the various stages of instruction processing

Field Programmable Gate Arrays Optimized for multilevel circuit Static random access memory (SRAM) SRAM-based FPGA can be reprogrammed and on-the-fly during the operation of the sys.

Xilinx 4000 Series FPGA Structure

Application of FPGA to software Radios System with high sample rate System with very-high-order FIR filters because the algorithm can be implemented in parallel System with fast correlators because the LUT architecture of FPGA provides a fast and efficient way to build correlators

Trade-Offs in DSP, FPGA and ASIC Low complexity can be solved with DSP FPGA and ASIC tend to be more useful when the complexity of the problem increases Using a combination of DSP, FPGA and ASIC.

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