Joint design of PAPR, PICR and OBP in OFDM systems
Master of Science
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Orthogonal frequency division multiplexing (OFDM) technique has been adopted by many existing and future wireless communication systems for high-speed data transmission. However, a major problem of OFDM systems is the high peak-to-average power ratio (PAPR) of OFDM signals, which results in inefficient operations of nonlinear devices in the system such as power amplifiers (PAs). On the other hand, at the receiver end, frequency offset, caused by Doppler frequency shifts, mismatched oscillators, or a fast fading channel, destroys the orthogonality among subcarriers and results in inter-carrier interference (ICI), thus degrades the detection performance of OFDM systems. Analogous to the definition of PAPR, the peak interference-to-carrier ratio (PICR) is defined to represent the effect of ICI. In addition, due to the sidelobes of modulated subcarriers, OFDM systems also suffer from high out-of-band power (OBP) radiations. High OBP results in the need for wide guard band and thus inefficient usage of frequency band.