Long-range radio communication method and device based on spreading factor index

A long-range radio communication system based on a spreading factor index, comprising:

• a transmitter and a receiver, wherein the transmitter is configured to modulate information bits within one symbol period into a plurality of second chirp signals, and superimpose all the second chirp signals to obtain a transmitted signal and transmit the transmitted signal to the receiver;
• the transmitter comprises a bit divider, a bit mapper, an index selector, a chirp signal generator, a base converter and a modulator;
• the bit divider is separately connected to the bit mapper and the base converter, and is configured to divide a plurality of information bits into a plurality of index bits and a plurality of modulated bits on the basis of the number of alternative spreading factors and an adjustable data rate parameter, transmit the index bits to the bit mapper, and transmit the modulated bits to the base converter;
• the bit mapper is connected to the index selector, and is configured to map the index bits into an element serial number set according to a combinatorial method on the basis of the number of alternative spreading factors and the adjustable data rate parameter, and transmit the element serial number set to the index selector;
• the index selector is connected to the chirp signal generator, and is configured to map the element serial number set into a spreading factor sequence on the basis of a preset sequence mapping table;
• and transmit the spreading factor sequence to the chirp signal generator;
• the chirp signal generator is connected to the modulator, and is configured to generate first chirp signals corresponding to various spreading factors on the basis of a plurality of spreading factors of the spreading factor sequence, and transmit the first chirp signals to the modulator, wherein the spreading factor sequence is S, S={s1, . . . , sK}, and K types of spreading factors are present in the spreading factor sequence;
• the base converter is connected to the modulator, and is configured to convert a plurality of modulated bits to decimal numbers associated with various spreading factors on the basis of the spreading factor sequence, and transmit the decimal numbers to the modulator;
• and
• the modulator is configured to modulate various decimal numbers into carrying signals, and multiply the carrying signals by the first chirp signals associated with the spreading factors to obtain second chirp signals associated with the various spreading factors.