The 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 the 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 the degree of the generatorPolynomial and each 1 bit at the ith position indicates that the x^i term has a 1 coefficient. Similarly, a 0 bit indicates a zero coefficient.

Inheritance diagram

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

Extends

Name	Type	Description
Module	compound module	Base module for all INET compound modules.

Parameters

Name	Type	Default value	Description
displayStringTextFormat	string	""	Determines the text that is written on top of the submodule, supports displaying pars, watches, and module-specific information
seed	string
generatorPolynomial	string

Properties

Name	Value	Description
class	AdditiveScramblerModule
display	i=block/tunnel

Source code

// The 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 the 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 the degree of the `generatorPolynomial` and each 1 bit at the ith
// position indicates that the x^i term has a 1 coefficient. Similarly,
// a 0 bit indicates a zero coefficient.
//
//
module AdditiveScrambler extends Module 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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