Scrambler module converts an input string into a seemingly random output string of the same length.

The seed parameter represents the initial contents of the shift registers which is a binary sequence, for example seed = "1011101".

The generator polynomial describes how the registers connect to the modulo 2 adder in the scrambler's hardware implementation. The links between the shift registers and a modulo 2 adder can be described with a polynomial in the following way: the x^7 + x^4 + 1 polynomial selects two registers: the 7th register and 4th register, and gives their contents as an input to the modulo 2 adder. The string representation of this polynomial is "0001001". The length of this string equals to deg(generatorPolynomial) and each 1 bits at the ith position indicate that the x^i term has a 1 coefficient. Similarly, 0 bit indicates a zero coefficient.

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Parameters

Name	Type	Default value	Description
seed	string
generatorPolynomial	string

Properties

Name	Value	Description
class	AdditiveScramblerModule
display	i=block/tunnel

Source code

// Scrambler module converts an input string into a seemingly random
// output string of the same length.
//
// The seed parameter represents the initial contents of the shift
// registers which is a binary sequence, for example seed = "1011101".
//
// The generator polynomial describes how the registers connect to the
// modulo 2 adder in the scrambler's hardware implementation.
// The links between the shift registers and a modulo 2 adder can be
// described with a polynomial in the following way: the x^7 + x^4 + 1
// polynomial selects two registers: the 7th register and 4th register,
// and gives their contents as an input to the modulo 2 adder. The string
// representation of this polynomial is "0001001". The length of this
// string equals to deg(generatorPolynomial) and each 1 bits at the ith
// position indicate that the x^i term has a 1 coefficient. Similarly,
// 0 bit indicates a zero coefficient.
//
//
module AdditiveScrambler like IScrambler
{
    parameters:
        string seed;
        string generatorPolynomial;
        @class(AdditiveScramblerModule);
        @display("i=block/tunnel");
}

File: src/inet/physicallayer/wireless/common/radio/bitlevel/AdditiveScrambler.ned

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