Sensors RSSI signal wireless communication ranging principle

What is the RSSI signal?

RSSI signal (Received Signal Strength Indication)——The received data signal strength indication, as an optional part in the wireless data transmission layer, is used to determine whether the quality of the transmission link is reliable and whether to increase the strength of broadcast data transmission.

RSSI technology is to determine the distance between the signal sending point and the receiving point by the strength of the received data signal. The data obtained by the receiver measurement circuit is the average signal strength indication of the received input, and the positioning calculation is performed according to these corresponding data. technology (this measurement generally excludes antenna gain and transmission system losses).

How does RSSI make distance measurements?

RSSI is a theoretical term for radio frequency signals, and is generally mainly used for distance measurement between a data sending station and a receiving station. It is a method of measuring the distance according to the received signal energy strength, which requires relatively high parameters of the transmission channel.

Ranging theory: According to the influence of the propagation efficiency of radio waves and sound waves in the medium, the transmission power of the signal will be attenuated due to the distance. The distance between the transmitting node and the receiving node can be calculated by the known power of the transmitting node and the receiving node of the existing signal target node, combined with the attenuation model between the signal and the distance. In the process of signal propagation, it may be indirectly affected by the transmission distance and shielding objects, which will affect the accuracy of the measurement to a certain extent. Therefore, if you want to pursue high-precision signals, short distances are a better choice. .

long-distance wireless ranging

At present, the signal sending and receiving of wireless sensor networks on the market all have the characteristics of simple communication structure, low cost and low power consumption. In response to the influence of different indoor and outdoor environmental factors, many attempts have been made to improve the accuracy of signal sending and receiving distance measurement. Methods: least squares method and multi-point positioning technology of beacon nodes, etc.

Comparison of wireless ranging methods

As can be seen from the above figure, RSSI technology based on RFID tags of WiFi technology has the advantages of lower cost and simpler operation than TOA, TDOA, AOA, and GPS centralized ranging technology. If the requirements for indoor positioning accuracy are not very high, then RSSI can be completely satisfied. For the current sensor network node, the node can obtain the RSSI measurement value by sending data packets. Moreover, RSSI technology can complete the analysis and processing of complex information without additional firmware, which reduces the cost of data communication consumption, and is very suitable for wireless communication networks.

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