| 摘要 |
An encoder is provided for generating rotationally invariant trellis codes when used with a signal constellation having m subconstellations indexed by j, each subconstellation having a plurality of points, where each subconstellation is a distinct rotation by j(360/m) degrees of another subconstellation such that no subconstellation has a point in common with another subconstellation. The encoder has a state block and a state update block. The state means receives q inputs i, and generates m outputs j, where m=pq and where p and q are integers greater than one and have no common factors. Outputs m are generated according to inputs i and states s of the state block according to j=i mod q and jd=s mod p, where the state block can assume n states, and n=md where d is an integer greater than one and has no common factors with p. The state update block updates the state block to a new state t chosen from the allowable n states based on the output j and previous state s according to t=jd+F(s-jd) mod n, where F is the permutation of 0, . . . , n-1, and is a function given by F(am+b)=bd+a for a=0, . . . , d-1, and for b=0, . . . , m-1.
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