Return to zero coded Gaussian minimum shift keying for wellbore electromagnetic wireless communications

Electromagnetic wireless communication in oil and gas wellbores faces challenges such as high bit error rates, limited channel bandwidth, and power constraints. Traditional digital modulation methods struggle to balance error performance with the power spectrum characteristics required for effective communication in these environments. To address this issue, we propose a Return to Zero coded Gaussian Minimum Shift Keying modulation method, based on GMSK with a BT value of 0.3. This method utilizes a bipolar return-to-zero code with a 70% duty cycle for differential encoding of the original signal, which serves as the input to a Gaussian filter. It mitigates the high bit error rate caused by inter-symbol interference in conventional GMSK while maintaining excellent power spectrum characteristics. The simulation results indicate that the modulation method proposed in this paper can simultaneously satisfy the requirements of oil and gas wellbore communication on the bit error rate performance and power spectrum characteristics, which further improves the reliability and effectiveness of oil and gas wellbore communication. Experimental results from wireless signal down-transmission in a real wellbore environment confirm that the RZ-GMSK signal can accurately transmit control instructions, meeting the needs of field operations.