Class for binary, narrow-sense BCH codes. More...

#include <itpp/comm/bch.h>

Inheritance diagram for itpp::BCH:

Public Member Functions
	BCH (int in_n, int in_k, int in_t, const ivec &genpolynom, bool sys=false)
	Initialize a (n,k)-code that can correct t errors.

	BCH (int in_n, int in_t, bool sys=false)
	Initialize a (n,k)-code that can correct t errors.

virtual	~BCH ()
	Destructor.

virtual void	encode (const bvec &uncoded_bits, bvec &coded_bits)
	Encode a bvec of indata.

virtual bvec	encode (const bvec &uncoded_bits)
	Encode a bvec of indata.

virtual bool	decode (const bvec &coded_bits, bvec &decoded_message, bvec &cw_isvalid)
	Decode the BCH code bits. Return false if there has been any decoding failure.

virtual void	decode (const bvec &coded_bits, bvec &decoded_bits)
	Decode a bvec of coded data. This function is kept for backward compatibility. Better use.

virtual bvec	decode (const bvec &coded_bits)
	Decode a bvec of coded data. This function is kept for backward compatibility. Better use.

virtual void	decode (const vec &received_signal, bvec &output)
	Decode a vec of received data.

virtual bvec	decode (const vec &received_signal)
	Decode a vec of received data.

virtual double	get_rate () const
	Get the code rate.

virtual int	get_k () const
	Get cardinality of code k.

BCH &	operator= (const BCH &)
	Dummy assignment operator - MSVC++ warning C4512.

Detailed Description

Class for binary, narrow-sense BCH codes.

The notation used is found in S. B. Wicker, "Error control systems for digital communication and storage", Appendix E, Prentice-Hall, 1995.

Example:

BCH bch(31,21,2,ivec("3 5 5 1"))

uses the generator polynomial $g(x) = x^{10} + x^9 + x^8 + x^6 + x^5 + x^3 + 1$ , and is capable of correcting 2 errors with n = 31 and k = 21.

Definition at line 59 of file bch.h.

Constructor & Destructor Documentation

itpp::BCH::BCH	(	int	in_n,
		int	in_k,
		int	in_t,
		const ivec &	genpolynom,
		bool	sys = `false`
	)

Initialize a (n,k)-code that can correct t errors.

Note: Do not call this constructor with e.g. BCH bch(31, 21, 2, "3 5 5 1") but with BCH bch(31, 21, 2, ivec("3 5 5 1")) instead. Otherwise the complier will complain.

Definition at line 39 of file bch.cpp.

References itpp::oct2bin(), itpp::GFX::set(), and itpp::zeros_i().

itpp::BCH::BCH	(	int	in_n,
		int	in_t,
		bool	sys = `false`
	)

Initialize a (n,k)-code that can correct t errors.

Author: Stephan Ludwig

The generator polynomial is automatically generated from the (n, t) parameters of the BCH code. The constructor generates the generator polynomial (and determines k) according to the method described in:

[Wic95] S. B. Wicker, "Error control systems for digital communication and storage", Prentice-Hall, 1995

Definition at line 51 of file bch.cpp.

References itpp::GFX::get_true_degree(), itpp::int2bits(), it_assert, itpp::length(), itpp::Array< T >::length(), itpp::GFX::set(), itpp::Array< T >::set_size(), and itpp::zeros_i().

Member Function Documentation

bool itpp::BCH::decode	(	const bvec &	coded_bits,
		bvec &	decoded_message,
		bvec &	cw_isvalid
	)

virtual

Decode the BCH code bits. Return false if there has been any decoding failure.

The coded_bits are block-wise decoded into decoded_message messages. If there has been any decoding failure, the function will return false. If this happened in the n-th block, then cw_isvalid(n) will be set to false (zero-indexed). In case of a systematic code the systematic bits will be extracted and presented in the corresponding block of decoded_message. This is better than just presenting zeros, which is done in case of a decoding failure of non-systematic codes.

Definition at line 208 of file bch.cpp.

References itpp::divgfx(), itpp::floor_i(), and itpp::zeros_b().

Referenced by decode().