Non-transitory storage medium storing a communication program and method of assigning pulse code train

A non-transitory storage medium storing a communication program for causing a computer to execute:

• a step of receiving a pulse code train;
• and
• a step of acquiring transmission information by decoding the received pulse code train according to assignment of each of one or more pulse code trains to a respective codeword;
• wherein
• each of the one or more pulse code trains includes four or more pulses, and
• each of the one or more pulse code trains is designed so that any pair of the one or more pulse code trains has a maximum of two common pulses under all possible shifts of a discrete number of time slots.

A method of assigning a pulse code train to a codeword,

• wherein a computer executes:
• a step of acquiring the number Nc of codewords;
• a step of organizing candidates for Nc pulse code trains assigned to respective codewords in blocks, wherein
• two fixed blocks and n-k free blocks are provided,
• each of the provided blocks comprises a two-dimensional array,
• a first axis of each of the blocks corresponds to a codeword,
• the number of elements in a first axis direction of each of the blocks is set to coincide with the acquired number Nc of codewords,
• a second axis of each of the blocks corresponds to the pulse code trains,
• each element arranged in a second axis direction at each position in the first axis direction of each of the blocks as an element string in the second axis direction disposed at each position in the first axis direction of each of the blocks indicates presence or absence of a pulse in the candidates for pulse code trains assigned to the respective codewords by representing presence of a pulse using a first value and representing absence of a pulse using a second value,
• each of the two fixed blocks is disposed at a respective one of a head and a tail in the second axis direction,
• the n-k free blocks are arranged in the second axis direction between the two fixed blocks,
• a series of element strings in the second axis direction extracted from each position in the first axis direction of the two fixed blocks and the n-k free blocks while being arranged in the second axis direction indicates each of the candidates for pulse code trains,
• in each of the two fixed blocks, the first value or a plurality of the first values are disposed in each element string in the second axis direction,
• in the two fixed blocks, a total number of the first values disposed in respective element strings in the second axis direction is k,
• n is equal to or greater than 4,
• k is equal to or greater than 2 and less than n,
• in each element string in the second axis direction in the fixed block disposed at the head in the second axis direction, the first value is disposed at the head in the second axis direction,
• in each element string in the second axis direction in the fixed block disposed at the tail in the second axis direction, the first value is disposed at the tail in the second axis direction,
• the number of elements in the second axis direction of each of the free blocks is equal to or greater than the acquired number Nc of codewords,
• organizing the candidates for Nc pulse code trains in blocks comprises disposing the first value in each element string in the second axis direction of each of the free blocks so that disposition of the first value does not overlap in the first axis direction and disposing the second value at each of the other positions;
• and
• a step of verifying the organized candidates for Nc pulse code trains, wherein
• each series of element strings in the second axis direction extracted from the two fixed blocks and the n-k free blocks is treated as each of the candidates for pulse code trains,
• for each of the candidates for pulse code trains, two pulse intervals between three freely-selected pulses are defined as a characteristic pair,
• verifying the candidates for Nc pulse code trains comprises determining whether or not there is a combination of coincident characteristic pairs in all characteristic pairs in the candidates for pulse code trains, wherein
• when it is determined that there is a combination of coincident characteristic pairs in the step of verifying, the computer reorganizes the candidates for Nc pulse code trains by changing disposition of the first value in at least one of the n-k free blocks, and executes the step of verifying on the reorganized candidates for Nc pulse code trains, and
• when it is determined that there is no combination of coincident characteristic pairs in the step of verifying, the computer adopts the organized candidates for Nc pulse code trains as pulse code trains assigned to the Nc codewords.