5. Introduction (Chapter objectives) Amplitude modulation and single sideband Frequency and phase modulation Digitally modulated signals(OoK, BPSK, FSK, MSK MPSK, QAM, QPSK, a/4QPSK, and OFDM) Spread sprectrum and CDMa system

《工程科学学报》：OFDM系统中基于最优阈值ACE的PAPR抑制

第七章我们讨论了数字调制的三种基本方式:数字振幅调制、数字频率调制 和数字相位调制,然而,这三种数字调制方式都存在不足之处,如频谱利用率低、 抗多径抗衰落能力差、功率谱衰减慢带外辐射严重等。 为了改善这些不足,近几十年来人们不断地提出一些新的数字调制解调技 术,以适应各种通信系统的要求。例如,在恒参信道中,正交振幅调制(QAM) 和正交频分复用(OFDM)方式具有高的频谱利用率,正交振幅调制在卫星通信和 有线电视网络高速数据传输等领域得到广泛应用

INFORMATION TO USERS This manuscript has been reproduced from the microfilm master UMl filt the text directly from the original or copy submitted. Thus, some thesis dissertation copies are in typewriter face, while others may be from any type of coMm

Introduction Frequency-selective fading is a dominant impairment in mobile communications Fading reduces receive signal-to-noise ratio and degrades the bit-error-rate(BER) Frequency selectivity of the channel, i. e, delay spread, induces inter-symbol interference(ISI) To combat frequency-selective fading

Enhancement of HIPERLaN/2 Systems using Space-Time Coding Mikael gidlund Radio Communication Systems Group Department of Signals, Sensors and Systems Royal Institute of Technology(KTh) SE-100 44 Stockholm. Sweden Email: mikael gidlund@mhse