itpp::Spread_1d Class Reference
[Digital Modulation]

Spreading of float symbols to float output. More...

#include <spread.h>

List of all members.

Public Member Functions
	Spread_1d ()
	Constructor.
	Spread_1d (const vec &incode)
	Constructor.
void	spread (const vec &symbols, vec &out)
	Spreading of signal return i out.
vec	spread (const vec &symbols)
	Spreading of signal.
void	despread (const vec &rec_signal, vec &out, int timing)
	Despreading of signal. timing is the start position of the first symbol, given in number of samples.
vec	despread (const vec &rec_signal, int timing)
	Despreading of signal. timing is the start position of the first symbol, given in number of samples.
void	set_code (const vec &incode)
	Set the spreading code used for spreading.
vec	get_code ()
	Returns the spreading code used.
int	get_period ()
	Get the period of the code (length of code vector).
Protected Attributes
vec	code
	The spreading code.
int	N
	The spreading factor.

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Detailed Description

Spreading of float symbols to float output.

Spreading block for generation of 1-dimensional DS-CDMA signals Useful in the simulation of DS-CDMA systems on chip level or upsampled chip level.

Obeserve that the spreading is normalized so that the energy per bit is preserved before and after spreading (that is each symbol is multiplied with 1/sqrt(N)). Hence, for the multicode case the energy is normalized for one symbol (code) but the transmitted signal consist of a sum of several signals.

Four different classes exist:

• Spread_1d for 1-dimensional symbols (e.g. BPSK).
• Spread_2d for 2-dimensional symbols (e.g. QPSK).

For multicode transmission, that is each user uses several codes in parallel to transmit data, there exist

• Multicode_Spread_1d for 1-dimensional symbols.
• Multicode_Spread_2d for 2-dimensional symbols.

Example:

  #include "itpp/itcomm.h"

  int main() {

  //Generate the spreading code you want to use.
  vec spreading_code = "-1 1 -1 1";

  //Initiate th Spreading class
  Spread_1d spread_1d(spreading_code);

  //Generate the symbols to transmitt
  bvec transmitted_bits = randb(10);
  BPSK bpsk;
  vec transmitted_symbols = bpsk.modulate_bits(transmitted_bits);

  //Spread the symbols
  vec transmitted_signal = spread_1d.spread(transmitted_symbols);

  //Generate the received signal
  vec received_signal = transmitted_signal;

  //Despread the received signal
  vec received_symbols  = spread_1d.despread(received_signal,0);

  //demodulate the bits
  bvec received_bits = bpsk.demodulate_bits(received_symbols);

  }

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The documentation for this class was generated from the following files:

• spread.h
• spread.cpp