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/*!
* \file
* \brief Definitions of binary sequence classes and functions
* \author Tony Ottosson and Pal Frenger
*
* -------------------------------------------------------------------------
*
* IT++ - C++ library of mathematical, signal processing, speech processing,
* and communications classes and functions
*
* Copyright (C) 1995-2008 (see AUTHORS file for a list of contributors)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* -------------------------------------------------------------------------
*/
#ifndef SEQUENCE_H
#define SEQUENCE_H
#include <itpp/base/vec.h>
#include <itpp/base/mat.h>
namespace itpp {
/*!
\brief Binary Linear Feedback Shift Register (LFSR)
\ingroup sequence
- The LFSR is on Fibonacci form (see p. 104 in Peterson, Ziemer and
Borth, "Introduction to Spread Spctrum communications", Prentice-Hall,
1995)
- If the connect_polynomial=1+g1*D+g2*D^2+...+gr*D^r is a primitive
polynomial, a Maximum Length Sequence (m-sequence) of length N=2^r-1 is
constructed. Use an arbitrary state not equal to zero, to get a phase of
the m-sequence
- For a table of primtive polynomials see p. 117 in the reference above
or a suitable book on coding
*/
class LFSR {
public:
//! Constructor
LFSR(void) {};
//! Input connect_polynomial=1+g1*D+g2*D^2+...+gr*D^r in bvec format [g0,g1,...,gr]
LFSR(const bvec &connections);
//! Input connect_polynomial=1+g1*D+g2*D^2+...+gr*D^r in octal format
LFSR(const ivec &connections);
//! Input connect_polynomial=1+g1*D+g2*D^2+...+gr*D^r in bvec format [g0,g1,...,gr]
void set_connections(const bvec &connections);
//! Input connect_polynomial=1+g1*D+g2*D^2+...+gr*D^r in octal format
void set_connections(const ivec &connections);
//! Set state (contents in the shift registers) in bvec format
void set_state(const bvec &state);
//! Set state (contents in the shift registers) in octal format
void set_state(const ivec &state);
//! Shift one step and output binary symbol
bin shift(void);
//! Shift no_shifts steps and output bvec
bvec shift(int no_shifts);
//! Return length of shift register
int get_length(void);
//! Returns the state of the shift register
bvec get_state(void);
private:
bvec memory, Connections;
};
/*!
\brief Gold Sequences
\ingroup sequence
*/
class Gold {
public:
/*!
\brief Class constructor
Automatic selection of a preferred pair of connections. Just give the
degree \f$N = 2^{deg} - 1\f$ where \f$deg = \{ 5, 7, 8, 9 \}\f$.
Only one pair is available for each degree.
*/
Gold(int degree);
//! Input connect_polynomials=1+g1*D+g2*D^2+...+gr*D^r in bvec format [g0,g1,...,gr]
Gold(const bvec &mseq1_connections, const bvec &mseq2_connections);
//! Input connect_polynomials=1+g1*D+g2*D^2+...+gr*D^r in octal format
Gold(const ivec &mseq1_connections, const ivec &mseq2_connections);
//! Set state (contents in the shift registers) in bvec format
void set_state(const bvec &state1, const bvec &state2);
//! Set state (contents in the shift registers) in octal format
void set_state(const ivec &state1, const ivec &state2);
//! Shift one step and output binary symbol
bin shift(void);
//! Shift no_shifts steps and output bvec
bvec shift(int no_shifts);
//! Returns the length (period) of a Gold-sequence
int get_sequence_length(void);
/*!
\brief Returns the code family
The Gold code family is defined by the two m-sequences (\a mseq1 and \a mseq2 ) and the sum
of \a mseq1 and all time shifts of \a mseq2. The return matric thus contain \a N + 2 rows
and \a N columns, where \a N is the length of the m-sequences.
*/
bmat get_family(void);
private:
int N;
LFSR mseq1, mseq2;
};
// --------------- Inlines ---------------------
inline bin LFSR::shift(void) {bin temp=memory*Connections;memory.shift_right(temp);return temp;}
inline int LFSR::get_length(void) {return memory.size();}
inline bvec LFSR::get_state(void) {return memory;}
inline bin Gold::shift(void) {return (mseq1.shift()+mseq2.shift());}
inline int Gold::get_sequence_length(void) {return N;}
// --------------- Functions ---------------------
/*!
\brief Generates the OVSF (orthogonal variable spreading factor)
spreading codes used in WCDMA.
\ingroup sequence
The codes are written row-wise in the return matrix.
*/
smat wcdma_spreading_codes(int SF);
} // namespace itpp
#endif // #ifndef SEQUENCE_H
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