High-speed transmission of LWD signals is difficult to achieve by current technology.The existing downhole mud pulse transmission technology cannot meet the requirements due to its low transmission rate.To cope with this problem

this paper improves while-drilling wireless transmission system with orthogonal frequency division multiplexing (OFDM)

which will result in more efficient data transmission.However

the high peak-to-average power ratio (PAPR) of the logging signals in the OFDM will gravely impact its performance.To further improve OFDM drilling wireless transmission system

we propose an SLM algorithm using radix-4 inverse fast Fourier transform (IFFT) to reduce PAPR.In this method

the radix-4-based IFFT performance at point N=4n is partitioned into two stages:transform before k and transform after n-k

between which the phase sequences are multiplied by an input signal.Theoretical analysis shows that

compared with the traditional SLM algorithm

the new SLM reduces the computational complexity almost by 60%.