Partial-prefix synchronizable codes

A new class of codes for frame synchronization is proposed, Commonly, the b eginning of every fixed or variable-length frame is identified by a given c ontiguous sequence called a prefix, To avoid the occurrence of the prefix e lsewhere in the frame, a prefix synchronizable code (PS-code) is used. PS-c odes have the property that the prefix does not occur in any codeword or in any concatenation of codewords in any position other than the first positi on. The new codes, termed partial-prefix synchronizable codes (PPS-codes), use a fixed sequence of symbols that is interspersed with symbols that carr y information, The contiguous sequence from the first fixed symbol to the l ast fixed symbol is called a "partial-prefix." Consequently, not one but a set of possible prefixes is used, and none of these prefixes is allowed to occur at any other than the first position of a codeword, The cardinality o f PPS-codes is determined, and coding algorithms are proposed which have a computational complexity proportional to the length of the codewords, It is demonstrated that in comparison with PS-codes, PPS-codes have similar codi ng and prefix detection complexity, but they have a larger code size and ha ve better error control capabilities.