| CPC H04L 5/006 (2013.01) [H04B 7/195 (2013.01); H04L 5/0048 (2013.01); H04L 5/0055 (2013.01)] | 13 Claims |

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1. An operation method of an Internet of things (IOT) terminal performing communications with a satellite, the operation method comprising:
receiving a first signal from the satellite;
determining a number of symbols constituting a preamble based on the first signal;
generating a first frame including a first preamble generated according to the determined number of symbols, and transmitting the generated first frame to the satellite; and
generating a second frame including a second preamble generated according to the determined number of symbols when a response signal to the first frame is received from the satellite, and transmitting the generated second frame to the satellite,
wherein the second preamble is configured identically to the first preamble, or configured differently from the first preamble, and the determined number of symbols is increased or decreased based on a result of comparing a signal-to-noise ratio (SNR) value measured for the first signal with a threshold,
wherein the threshold is set according to a reception capability of the terminal or the satellite.
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