SNR estimation and bit allocation applied in logging telemetry equipment

Nowadays many logging communication systems adapt the Orthogonal Frequency Division Multiplexing (OFDM) for the implementation of high transmission rate. In order to realize higher rate, adaptive bit allocation is proposed, which is based on signal-to-noise ratio (SNR). SNR is a significant evaluation parameter for the channel quality in the communication systems. In this paper, we derive a SNR estimation method for the logging cable channel. Simulation results show that the proposed algorithm is available to obtain relatively accurate measurements of SNR. On the basis of measurements, we assign the bits for sub-channels by a simplified bit allocation method. Compared with fixed bit allocation, this method improves the transmission rate.