QPSK modulation and demodulation implementation on CEVA XC-321 DSP for IEEE 802.11b Wi-Fi phone application

This work aims to design and implement Quadrature Phase Shift Keying (QPSK) baseband modulation-demodulation (MODEM) system on the CEVA-XC321 fixed point digital signal processor (DSP) and to compare its performance with industry standard DSP processors and FPGA based implementations. The modem function was developed in Vec-C language by utilizing two Vector Computation Units (VCU) of CEVA and verified on CEVA-XC321 based emulation platform. The implementation of the modem functions includes sampling, NRZ encoding, QPSK modulation, data packet formation using payload and packet header, receiver matched filtering, QPSK demodulation and decision device. We have considered additive white Gaussian Noise (AWGN) channel to analyze the effect of the channel on the transmitted data packet. The implementation results and the theoretical results are consistent and ascertained the correctness of this design. The modem parameters are selected in accordance with IEEE 802.11b Wi-Fi standard. We have tested the QPSK modem implementation in conformance to 802.11b Wi-Fi performance metrics and established its applicability in Wi-Fi phone system. The results showed that the proposed DSP based QPSK implementation can greatly improve the performance efficiency with less development time and cost for high data rate wireless local area network (WLAN) applications.