 the received signal vector in the frequency domain can be expressed as (6.9) where H m is the diagonal matrix of channel response and Wm m is the noise vector. In this system, the maximum excess delay of the channel is assumed to be shorter than the cyclic prefix duration; therefore, the intersymbol interference (ISI) can easily be eliminated by removing the cyclic prefix. The linear amplitude and phase distortion in the received signal as a result of the multipath channel is compensated by a frequency domain equalizer (FDE). After FDE, the output signal is vm=CmXxm (6.10) where Cm is the matrix diagonal of FDE coefficients: (6.11) The FDE coefficient generation is described in Section 6.5, where we describe the additional link-level processing required for a coded and more practical system. The steps presented in Equations (6.5) to (6.11) form the basis for the link-level model in Section 6.5. 6.4 Peak-to-Average Power Ratio Evaluation The envelope variation of the transmitted signal can be represented in a PAPR. In this work, the PAPR of both SC-FDMA and OFDMA is evaluated. The PAPR is an essential parameter that can affect the radio frame (RF) part because a transmitter signal with high PAPR is sensitive to the nonlinear distortion at the power ampli- fier. The PAPR of the transmitted signal can be expressed as CCDF(Pin) (6.12) © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology pi/2 BPSK 16QAM 64QAM PT (dB) Figure 6.4 PAPR of SC-FDMA with various modulation schemes. where Pins is the instantaneous power of the signal, Vi is the ith signal samples, Pavg is the long-term average power, and PT is the power threshold of the signal. For simplicity, Pavg has been normalized to one. In order to obtain accurate results, the transmitted signal has been oversampled four times according to the suggestion given in Han and Lee [7]. Figure 6.4 shows the PAPR results for SC-FDMA with various modulation schemes. The PAPR results vary depending on the modulation scheme, SO higher