Combination of PAPR reduction and linearization for the OFDM communication system

Orthogonal frequency division multiplexing (OFDM) has been widely used in many kinds of communication systems. However, OFDM signal has serious problem of high peak‐to‐average‐power ratio (PAPR) due to so many sub‐carriers. So, OFDM signal has very wide dynamic range. Therefore, the bit error rate (BER) performance may be degraded because of the nonlinear devices like the high power amplifier (HPA). Even if the linearization and large back‐off are used to compensate for the HPA nonlinearity, the power efficiency of the HPA is still very low since the PAPR is very high. Therefore, the PAPR reduction of the OFDM signal before the linearization would be more reasonable to improve the power efficiency and nonlinear compensation at the same time. In this paper, we propose a new combined method of SPW (sub‐block phase weighting) for PAPR reduction and linearization technique for the improvement of the power efficiency and for the nonlinear compensation of HPA. An updated SPW method is proposed to use a novel weighting factor multiplication of the complementary sequence characteristic and PAPR threshold technique. From the simulation results, it can be confirmed that BER performance is significantly improved and out‐of‐band spectrum radiations are much mitigated. Power efficiency of HPA can be enhanced since we can set small IBO (input back‐off) due to the PAPR reduction. The proposed system shows about 3 and 1 dB performance improvement than the LCP (linearized constant peak‐power)‐OFDM and LCP‐OFDM plus SPW at BER = 10−4. Copyright © 2010 John Wiley & Sons, Ltd. In this paper, we propose a new combined method of SPW (subblock phase weighting) for PAPR reduction and linearization technique for the power efficiency improvement and for the nonlinear compensation of HPA. Updated SPW method is used for the novel weighting factor multiplication of the complementary sequence characteristic and PAPR threshold technique. From the simulation results, it is confirmed that BER performance is significantly improved and out‐of‐band spectrum radiations are much mitigated. Also, power efficiency of HPA can be improved.