Method

Algebraic method to generate permutation vector

Specify the algebraic method as one ofTakeshita-Costello|Welch-Costas. The default isTakeshita-Costello. The algebraic interleaver performs all computations in moduloN, whereNequals the length you set in theLengthproperty.

For theWelch-Costasmethod, the value of (N+ 1)必须是一个质数,在哪儿eNequals the value you specify in theLengthproperty. You must set thePrimitiveElementproperty to an integer,A, between 1 andN. This integer represents a primitive element of the finite fieldGF(N+1).

For theTakeshita-Costellomethod, you must set theLengthproperty to a value equal to 2^m, for any integerm. You must also set theMultiplicativeFactorproperty to an odd integer that is less than the value of theLengthproperty. TheCyclicShiftproperty requires a nonnegative integer which is less than the value of theLengthproperty. TheTakeshita-Costellointerleaver method uses a cycle vector of lengthN, which you specify in theLengthproperty. The cycle vector calculation uses the equation, $$\text{mod(}k\times \text{(}n-\text{1)}\times \frac{n}{2}\text{,}N\text{)+1}$$ , for any integern, between 1 andN. The object creates an intermediate permutation function using the relationship, $$P\text{(}c\text{(}n\text{)) =}c\text{(}n\text{+1)}$$ . You can shift the elements of the intermediate permutation vector to the left by the amount specified by theCyclicShiftproperty. Doing so produces the interleaver's actual permutation vector.