Implementation of OFDM Communication System using DSP Development Platform

• Main Authors: Wang, Ting-Feng, 汪庭鋒
• Other Authors: Hung, Hsien-Sheng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/03851631247622389825

碩士 === 國立臺灣海洋大學 === 電機工程學系 === 103 === In this thesis, a communication system with orthogonal frequency division multiplexing (OFDM) is designed and implemented using a digital signal processor (DSP) development platform. We use TI’s TMS320C6416 DSP Starter Kit (DSK) as the development platform which consists of multi-channel buffered serial port, TLV320AIC23 audio codec chip, and Code Composer Studio (CCS). Design of communication system’s software routines is accomplished using C programming language which is compiled in CCSv3.3 development software. But in the CCS compiler, C programming language must fully comply with ISO C’s standards; otherwise, it can’t be successfully compiled and executed. Transmitter involves several steps of signal processing. Firstly, texts to be transmitted are entered by the user and converted into binary codes with ASCII encoding. Next, the bit stream is processed via QPSK modulation, inverse fast Fourier transform, and guard interval insertion to obtain OFDM symbols. Finally, audio signals are generated by passing OFDM signals through AIC23 audio chip and headphone. In the receiver part, signal processing is mainly performed with steps just being opposite to the counterparts in the transmitter. First, the received OFDM signal is retrieved by AIC23 audio chip with microphone. Next, digital signal processor locates the starting signal to retrieve the OFDM symbols after it, removes the guard interval of each OFDM symbol, computes its spectral values via fast Fourier transform, and estimates the data bits by passing them through the QPSK slicer (hard-decision device). Experimental results show that the bit error rate is about ten percent, which is not so good. The reason behind it may be the low-frequency noise from computers and surroundings. Keyword：Orthogonal frequency division multiplexing, Digital signal processor, Phase modulation, Audio chip, Bit error rate.