상세정보
학술대회
A design of QAM modulator for multicode WCDMA
- 저자
- 박형숙, 박윤옥, Cheol-Sung Kim
- 발행일
- 200308
- 출처
- Radio and Wireless Conference (RAWCON) 2003, pp.187-190
- 초록
- A QAM modulator using multiple four-output FIR filters based on look-up table (LUT) is proposed for downlink of wideband CDMA systems, and its functions are verified by stand-alone tests by means of the test equipment that achieves the functions of a QAM receiver system. Because a modulator employs the multicode modulation and M-QAM unlike QPSK modulation, the FIR filter for pulse shaping requires the multi-bit input word. So we propose the filter structure with multi-bit input word, which consists of multiple four-output FIR filter and bit-weighted accumulators. It is easy to extend the filter structure as increase of input bit word without higher clock frequency. We measure the spectrum of the implemented modulator by using a spectrum analyzer. Also, the demodulated signal constellation is obtained in the case of 16, 64 and 256-QAM as increase of multicode number.
- KSP 제안 키워드
- 256-QAM, CDMA systems, Clock frequency, Finite Impulse Response filter(FIR filter), M-ary quadrature amplitude modulation(M-QAM), Pulse shaping, QAM modulator, QPSK modulation, Spectrum analyzer, Stand-Alone, Test Equipment