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

FlexibilityFlexibility-Overall system clock rate be adjustable in different data rate

ModularityModularity-allow easy replacement or upgrading of subsystem

ScalabilityScalability allow the radio to be enhance to improve capability (increase channels)

PerformancePerformance Power consumption, cost ,computational

capability metrics

Hardware Elements

DSPsDSPs:: microprocessor-based, support high level languages like C, offer the most flexibility

ASICsASICs :circuit in fixed silicon ,optimized speed and power consumption, requires sophisticated circuit design and layout software tools.

FPGAsFPGAs: provide much hardware-level reconfigu-rability, flexibility: DSP>FPGA>ASIC.

Tools for FPGA are similar to those for ASIC

TradeTrade: 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 gene

ral control application

Categories of general available DSPs

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 becau

se 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.

End

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