edict power de-rating based on the information that has been collected from several devices for a variety of signals. The cubic metric can be calculated using the following equation [121]: 2010g(snormous) 20log Snorm-referencerms (9-17) Where Snormrms denotes the RMS value of the normalized voltage waveform of the input signal and norm-referencerms is the RMS value of the normalized voltage waveform of the reference signal (i.e., signal generated using 12.2 kbps AMR speech codec [121]). The CM is used to model the impact non-linearity in the power amplifier on the adjacent channel leakage ratio. A small value of the CM represents a small power amplifier back-off. The CM is insensitive to the highest power values of the distribution that only have very low probabilities. Thus, methods to reduce the PAPR may not have any major impact on the CM. The value of parameter K was empirically determined to be 1.85 for a set of WCDMA signals. In other words, this equation computes the cubic power of a signal s(t) and compares it to a reference signal Sreference and uses the empirical slope factor K to estimate the CM value. 9.4 Downlink and uplink multiple access schemes Table 9-1 Example CM Values Corresponding to Reference [122] Signal Modulation RAW CM (dB) Bandwidth Offset (dB) CM (dB) WCDMA Voice 16 QAM DFT-S OFDM DFT-S OFDM 16 QAM DFT-S OFDM 64 QAM IFDMA IFDMA 16 QAM IFDMA 64 QAM Although the signal vectors are shown as a function of time, the time scale is effectively removed in the RMS operation and is not a part of the computation. Thus, the raw CM result is not a function of symbol rate or alternatively not a function of signal bandwidth. Similarly, a change in chip rate has no affect on the PAPR. The bandwidth effects will be significant in this study since it includes signals with 3 dB bandwidths larger than the 3.84 MHz used for WCDMA. Table 9-1 shows the CM values cor- responding to some example input signals, such as OFDM, DFT-S OFDM, and Interleaved Frequency Division Multiple Access (IFDMA) which is a varia