SIMPLE ENCODING/DECODING TECHNIQUE FOR CODE POSITION MODULATION

摘要

A method and apparatus for encoding and decoding signals using code position modulation (CPM) in a communication system. The encoding method includes storing an N-chip pseudo-random noise sequence, such as an m-sequence, in a circular shift register (402) and circular shifting it to obtain a shifted m-sequence. The shifted m-sequence is compared (408) to an m-bit symbol corresponding to the k bit information value. If the shifted m-sequence and the m-symbol match, the shifted m-sequence is output as the N-chip CPM sequence. Alternatively, the m-symbol is used as an initial condition for a pseudo-noise sequence generator. The corresponding decoder stores an N-chip n-sequence in a circular shift register and a correlates shifted version of the m-sequence in a N-chip CPM sequence. When a peak in the correlation value is detected, an m-bit field is retrieved from the circular shift register (402) and mapped to a k-bit information value.