# Research on New Drilling Downlink Communication Based on Anisotropic Magnetoresistive Technology
## 5 Conclusions  
Based on the analysis of the principle of anisotropic magnetoresistance detection and the theory of downhole electric current field, a new technology of downlink communication while drilling technology is studied in this paper. The communication technology is first used in the process of information downlink communication while drilling. It has the advantages of fast communication speed, low BER, simple structure, convenient implementation, and low cost. Through the experimental studies, the following conclusions can be drawn:  
1. In order to study the structure of the underground wireless communication system, the system structure model is established; at the same time, the current distribution model and magnetic field distribution model of different positions of downhole power drill string are established based on the anisotropic magnetoresistance detection principle and downhole electric current field theory. The design of the laboratory prototype of the downlink communication system based on anisotropic magnetoresistance is realized
2. To verify the feasibility of the proposed information downlink communication technology while drilling, a ground experimental platform simulating the downhole communication state is built, and the principle prototype is tested. The test results show that when the communication distance is 9 cm and the data transmission rate is 1 kbps, the maximum BER of the simulation system based on anisotropic magnetoresistance detection is 1.02%
3. For the purpose of further analyzing the influence factors of downlink communication quality, the emission voltage, the distance between electrodes, and the working temperature are tested and analyzed. The experimental data show that the transmission voltage and the temperature of the test environment have great impacts on the experimental BER, which provides a reference for further reducing the BER and ideas for optimizing the technology of downlink information communication while drilling
4. Although the system has completed the theoretical research and realized the small-scale model verification, it is still in the laboratory application stage and has certain limitations, such as: no study on the effect of rock properties. In the future work, the in-situ verification experiment of complex downhole conditions will be carried out to further enhance its application value.  
Figure 14: BER comparison under different temperature conditions.  
**Author Contributions:** Conceptualization, L.G.; methodology, L.G., L.Z. and Y.H.; software, H.L. and XX.; validation, L.G., L.Z. and Y.H.; formal analysis, L.Z. and Y.H.; data curation, L.Z. and H.L.; writing--original draft preparation, L.G., X.X. and Y.H.; writing--review and editing, L.G., L.Z. and C.Y. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work is supported by the National Natural Science Foundation (51974273), the International Science and Technology Cooperation Project of Chengdu (2020-GH02-00016-HZ), and the Special Project of Science and Technology Strategic Cooperation between Nanchong City and Southwest Petroleum University (SXHZ026/SXHZ038).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.