midamble.h

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

#ifndef _MIDAMBLE_H__
#define _MIDAMBLE_H__

#include "mmx.h"
#include "spc.h"
#include "antenna.h"

#define NUM_MIDAMBLE_DEF 4
#define MAX_MIDAMBLE_PERIOD 512
#define MAX_CHANNELS 16
#define MAX_SPREADING_FACTOR 16
#define MAX_CH_EST 4


typedef struct{
  // length in chips
  unsigned int   length;
  // sequence period in chips
  unsigned int   period;
  // sequence shift between 2 consecutive channels [chips]
  unsigned int   shift;
  // max number of channels allowed by the midamble.
  unsigned int   max_channels;
  // midamble generator (of length 'period' bits) 
  unsigned int   *generator;       
  // midamble table. Contains the midamble for each user.
  //  Is a vector of size length*max_channels bits 
  unsigned int   *midamble_table;  

  // channel estimation fields
  // midamble generator in the frequency domain (length: period mmx_t units)
  //   format: |Re0 -Im0 Im0 Re0|...
  mmx_t          *generatorF;      
  // twiddle for FFT
  mmx_t          *twiddleFFT;      
  // twiddle for IFFT
  mmx_t          *twiddleIFFT;     
  // reverse buffer: it is used when reordering the elements before the FFT/IFFT
  unsigned short *revbuf;          
  // For the estimation-channel function
  int            (*estimate_channel)(mmx_t *, mmx_t *, mmx_t *, 
				     mmx_t *, mmx_t *, unsigned short int *);
} midamble_t;


typedef struct{
  // get_sequence is a pointer to the function that loads the spreading table
  // (given the amplitude and the index)
  unsigned int (*get_sequence)(void *, void * ,void *,void *, void *);  
  // pointer to the spreading sequence !! Warning:  64 may be a limitation!!
  mmx_t spreading_sequence[64]; 
  /** This vector is used to store the channel estimates given by 
   * a certain midamble 'mid'. The vector is divided into 
   * 'mid->max_channels' parts.  Each part has length 
   * 'mid->shift*DAQ_SAMPLES_PER_CHIP' mmx_t elements. The i-th part 
   * contains the response of the 'max_channels-i' channel 
   * (for i=0...max_channels-1) The format of the mmx_t element is
   * | Re0 Im0 Re0 Im0 | Re1 Im1 Re1 Im1 | ...
   */
  mmx_t estimates[ DAQ_SAMPLES_PER_CHIP * MAX_MIDAMBLE_PERIOD ];
  // temp buffer for the spreading sequence
  mmx_t temp_buffer[ DAQ_SAMPLES_PER_CHIP * ( MAX_MIDAMBLE_PERIOD + 
					      2 * MAX_CHANNELS * 
					      (MAX_SPREADING_FACTOR-1))];
  mmx_t temp_sequence[ MAX_SPREADING_FACTOR ]; 
  /** is the pointer to the MF vector (real part). 
   * The vector is divided into 'max_channels' parts, each one
   */
  short matched_filter_Re[ DAQ_SAMPLES_PER_CHIP * MAX_MIDAMBLE_PERIOD ];
  /** is the pointer to the MF vector (imag part). 
   * The vector is divided into 'max_channels' parts, each one
   */
  short matched_filter_Im[ DAQ_SAMPLES_PER_CHIP * MAX_MIDAMBLE_PERIOD ];
  /** chosen length of the channel estimate, can be lengthened 
   * or shortened according to performance/complexity requirements
   */
  int estimation_length;
} estimation_vars_t;

extern midamble_t midamble_def[ NUM_MIDAMBLE_DEF ];

void midamble_prepare( void );
int midamble_write( int mid_type, SYMBOL_COMPLEX *out_mid, unsigned int amp, 
		    unsigned short mid_index );
int midamble_add( int mid_type, SYMBOL_COMPLEX *out_mid, unsigned int amp, 
			unsigned short mid_index );
int midamble_get_nbr_channels( int mid_type );
int midamble_get_length( int mid_type );

int rcv_module_init(void);
void rcv_module_exit( void );
int send_module_init(void);
void send_module_exit( void );


//Mimo part

int mimo_mid_module_init( void );
void mimo_mid_module_exit( void );

#endif