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Cross-border Magnetic Induction Relay Cooperative Communication Scheme Based on Distributed Space-time Coding

The application prospect of air-sea cross-border communication is broad. Magnetic induction (MI) communication can realize two-way cross-border transmission, adapt to complex marine environment and be easy to carry. Therefore, it has unique advantages in cross-border transmission. However, due to the characteristics of near field propagation in magnetic induction communication, the range × data rate performance of magnetic induction communication is severely limited, which is a difficult bottleneck problem to break through. Aiming at this problem, this paper proposes a cross-border magnetic induction relay cooperative communication scheme based on distributed space-time coding. In this scheme, relay nodes are introduced between the transmission and reception of cross-border transmission, and distributed space-time coding (DSTBC) is used on the relay nodes to coordinate the forwarding of each relay node so as to obtain the spatial diversity gain. Using the diversity gain, the underwater communication range of cross-border communication can be extended. Simulation results show that the DSTBC coding scheme can significantly improve the transmission performance of wireless channels. When the system bit error rate is 10-4, compared with the simple forwarding relay system, the code-forwarding system using 2, 3, and 4 relay nodes can obtain about 3 to 6dB of diversity gain.