Abstract: Embodiments of the present invention provide a method for retransmission based on forward error correction. The method includes: when received source data packets loss occurs, judging whether all of the lost source data payloads can be decoded by using the received source data payloads and check data; if all of the lost source data payloads cannot be decoded, determining needed source data symbols for decoding all of the lost source data payloads by using the received source data payloads and the check data; and requesting for retransmitting the needed source data symbols.

Abstract: A noise elimination method based on sound ray refraction theory and the muffler thereby are disclosed. The method use s low temperature refrigeration system (2) to form a temperature gradient inside and outside the chamber of the muffler, and the temperature inside the pipe wall of the chamber is higher than the outside. The temperature gradient may force sound ray to reflect towards the low temperature direction, so the noise of the system may be captured and reduced. The muffler comprises a housing (1) whose inner wall is laid with a sound absorbing structure (4), and on the outer wall of the housing (1) is provide a low temperature refrigerating system (2). The system covers at least of the area of the outer wail of muffler housing (1) and combines with a temperature control system (3) to realize quantitative control of the temperature gradient. The muffler improves the noise-absorbing effect of the existing muffler effectively.