Which of the following indicates the number of input bits that the current output is dependent upon?

The correct answer is D. Constraint length.

The constraint length is a parameter of a convolutional code that indicates the number of input bits that the current output is dependent upon. A longer constraint length results in a more complex code, but also in a code that is more resistant to errors.

Code length is the total number of bits in the code. Search window is the number of previous and future symbols that are considered when decoding a symbol. Information rate is the ratio of the number of information bits to the total number of bits in the code.

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