Method for transmitting useful information between two terminals and method for generating an association table used in the context of the transmission
A method for transmitting useful information between a transmitting terminal and a receiving terminal connected via a transmission channel. The transmitting terminal defines control information for the useful information, and searches in an association table, which is accessible from the transmitting terminal, for a frame-synchronization word associated with the control information. The transmitting terminal generates a frame of data from the useful information, and transmits, over the transmission channel, a data stream that includes the frame-synchronization word and the frame of data.
1. A method for generating an association table between frame synchronization words and control information items, comprising the steps of:
defining all possible control information items;
defining a set of frame synchronization words according to a number of possible control information items by:
defining a length L of the frame synchronization word according to the number of possible control information items such that the length L is sufficient to distinguish all the possible control information items;
listing a set of permutations of a word of the length L to obtain a set of raw words; and
filtering the set of raw words to obtain the set of frame synchronization words; and
associating, with each possible control information item, a frame synchronization word in the set of frame synchronization words.
2. The method as claimed in claim 1 , wherein the step of filtering the set of raw words comprises the steps of:
calculating, for each raw word, a sliding correlation between said each raw word and an association word comprising said each raw word concatenated with a reference word;
calculating a ratio between an absolute maximum of the sliding correlation and a local maximum of the sliding correlation immediately below the absolute maximum; and
deleting from the set of raw words all raw words for which the ratio is below a predefined threshold.
3. The method as claimed in claim 2 , further comprising the step of calculating a sliding correlation for a number of realization less than a predefined number of realization by:
randomly generating the reference word;
generating the association word by concatenating said reference word with said each raw word;
calculating the sliding correlation between said each raw word and the association word;
saving values of the sliding correlation in response to determining the number of realization equals the predefined number of realization; and
calculating an average of the values of the sliding correlation.
4. The method as claimed in claim 1 , wherein the step of filtering the set of raw words comprises the steps of:
calculating, for each raw word, a number of different bits between said each raw word and other words of the set of raw words; and
deleting from the set of raw words one of two words compared in response to determining a result of the calculation of the number of different bits is below a threshold.
5. The method as claimed in claim 1 , wherein the step of filtering the set of raw words comprises the steps of:
calculating, for each raw word, a sliding correlation between said each raw word and an association word comprising said each raw word concatenated with a reference word;
calculating a ratio between an absolute maximum of the sliding correlation and a local maximum of the sliding correlation immediately below the absolute maximum; and
deleting from the set of raw words all raw words for which the ratio is below a predefined threshold;
calculating, for each remaining raw word, a number of different bits between said each remaining raw word and other words of the set of raw words; and
deleting from the set of raw words one of two words compared in response to determining a result of the calculation of the number of different bits is below a threshold.