Auto-ACK and ReSend are long-talked-about issues in our wireless communication. After the data is radiated into the air through the modulation circuit, how to judge whether the other party has received the data? If not received, what mechanism will be used to handle this exception?

In this system, there is always a need for a receipt, which is not necessarily able to reach full confidence for both parties, and we have not considered that the information of the signal soldier may be tampered with. It can be seen that the problem of the two armies in the classic situation is unsolvable, and there is no communication protocol that can enable the blue army to win.

As a problem that must be solved in the modern communication system, the issue between the two militaries cannot be completely solved yet, which means that information may still be lost, monitored or tampered with when you and I transmit information. But can we solve most cases in a relatively reliable way?
Auto-ACK (Auto-ACK):

In our actual communication, of course, the establishment of reliable communication will not be passed on indefinitely like the problem between the two armies. How to solve it is to join the Acknowledgement (ACK) mechanism.

This is a more commonly used data judgment method in our communication interaction. When the sender sends a data, if the receiver receives the data, it will switch to the sending mode and send an ACK frame. At this time, if the sender receives the ACK frame , it is determined that the data is sent successfully and the communication is completed. So what if the sender doesn't receive the ACK frame? How should we deal with it? Next, we introduce the retransmission mechanism.

The retransmission mechanism is determined by whether the ACK sent by the receiver is received after sending the data. If it is not received, the user or the MCU will determine whether to continue sending packets. This is the retransmission mechanism, as shown in Figure 3. After one transmission is completed, the sender does not receive an ACK response, so it resends a second time. At this time, the receiver opens the acceptance and responds to the sender with ACK, which marks the completion of the communication.

To sum up, it can be seen that the automatic response and retransmission mechanism is suitable for all communication fields. These two complementary methods enhance communication stability and ensure the effective transmission of data. In industrial sites, electromagnetic interference will be particularly prominent. When the sender When the ACK response is not received, it will mark the communication failure, and tell the user directly and clearly, and then let the user control and judge. The multi-node routing method makes wireless data packets resistant to various interferences in the air.