srsRAN_4G/srsue/src/phy/prach.cc

/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2015 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsUE library.
 *
 * srsUE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsUE 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 Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#include <string.h>
#include <strings.h>
#include <pthread.h>

#include "srslte/srslte.h"
#include "srslte/common/log.h"
#include "phy/prach.h"
#include "phy/phy.h"
#include "srslte/interfaces/ue_interfaces.h"

#define Error(fmt, ...)   if (SRSLTE_DEBUG_ENABLED) log_h->error_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Warning(fmt, ...) if (SRSLTE_DEBUG_ENABLED) log_h->warning_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Info(fmt, ...)    if (SRSLTE_DEBUG_ENABLED) log_h->info_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Debug(fmt, ...)   if (SRSLTE_DEBUG_ENABLED) log_h->debug_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)

namespace srsue {
 

prach::~prach() {
  if (mem_initiated) {
    for (int i=0;i<64;i++) {
      if (buffer[i]) {
        free(buffer[i]);
      }
    }
    if (signal_buffer) {
      free(signal_buffer);
    }
    srslte_cfo_free(&cfo_h);
    srslte_prach_free(&prach_obj);
  }
}

void prach::init(LIBLTE_RRC_PRACH_CONFIG_SIB_STRUCT *config_, uint32_t max_prb, phy_args_t *args_, srslte::log* log_h_)
{
  log_h  = log_h_;
  config = config_;
  args   = args_;

  for (int i=0;i<64;i++) {
    buffer[i] = (cf_t*) srslte_vec_malloc(SRSLTE_PRACH_MAX_LEN*sizeof(cf_t));
    if(!buffer[i]) {
      perror("malloc");
      return;
    }
  }
  if (srslte_cfo_init(&cfo_h, SRSLTE_PRACH_MAX_LEN)) {
    fprintf(stderr, "PRACH: Error initiating CFO\n");
    return;
  }
  srslte_cfo_set_tol(&cfo_h, 0);
  signal_buffer = (cf_t *) srslte_vec_malloc(SRSLTE_PRACH_MAX_LEN * sizeof(cf_t));
  if (!signal_buffer) {
    perror("malloc");
    return;
  }
  if (srslte_prach_init(&prach_obj, srslte_symbol_sz(max_prb))) {
    Error("Initiating PRACH library\n");
    return;
  }
  mem_initiated = true;
}

bool prach::set_cell(srslte_cell_t cell_)
{
  if (mem_initiated) {
    // TODO: Check if other PRACH parameters changed
    if (cell_.id != cell.id || !cell_initiated) {
      memcpy(&cell, &cell_, sizeof(srslte_cell_t));
      preamble_idx = -1;

      uint32_t configIdx      = config->prach_cnfg_info.prach_config_index;
      uint32_t rootSeq        = config->root_sequence_index;
      uint32_t zeroCorrConfig = config->prach_cnfg_info.zero_correlation_zone_config;
      uint32_t freq_offset    = config->prach_cnfg_info.prach_freq_offset;
      bool     highSpeed      = config->prach_cnfg_info.high_speed_flag;

      if (6 + freq_offset > cell.nof_prb) {
        log_h->console("Error no space for PRACH: frequency offset=%d, N_rb_ul=%d\n", freq_offset, cell.nof_prb);
        log_h->error("Error no space for PRACH: frequency offset=%d, N_rb_ul=%d\n", freq_offset, cell.nof_prb);
        return false;
      }

      Info("PRACH: configIdx=%d, rootSequence=%d, zeroCorrelationConfig=%d, freqOffset=%d\n",
            configIdx, rootSeq, zeroCorrConfig, freq_offset);

      if (srslte_prach_set_cell(&prach_obj, srslte_symbol_sz(cell.nof_prb),
                                 configIdx, rootSeq, highSpeed, zeroCorrConfig)) {
        Error("Initiating PRACH library\n");
        return false;
      }
      for (int i=0;i<64;i++) {
        if(srslte_prach_gen(&prach_obj, i, freq_offset, buffer[i])) {
          Error("Generating PRACH preamble %d\n", i);
          return false;
        }
      }

      len = prach_obj.N_seq + prach_obj.N_cp;
      transmitted_tti = -1;
      cell_initiated = true;
    }
    return true;
  } else {
    fprintf(stderr, "PRACH: Error must call init() first\n");
    return false;
  }
}

bool prach::prepare_to_send(uint32_t preamble_idx_, int allowed_subframe_, float target_power_dbm_)
{
  if (cell_initiated && preamble_idx_ < 64) {
    preamble_idx = preamble_idx_;
    target_power_dbm = target_power_dbm_;
    allowed_subframe = allowed_subframe_; 
    transmitted_tti = -1; 
    Debug("PRACH: prepare to send preamble %d\n", preamble_idx);
    return true; 
  } else {
    if (!cell_initiated) {
      Error("PRACH: Cell not configured\n");
    } else if (preamble_idx_ >= 64) {
      Error("PRACH: Invalid preamble %d\n", preamble_idx_);
    }
    return false; 
  }
}

bool prach::is_ready_to_send(uint32_t current_tti_) {
  if (cell_initiated && preamble_idx >= 0 && preamble_idx < 64) {
    // consider the number of subframes the transmission must be anticipated 
    uint32_t current_tti = (current_tti_ + tx_advance_sf)%10240;
    if (srslte_prach_tti_opportunity(&prach_obj, current_tti, allowed_subframe)) {
      Debug("PRACH Buffer: Ready to send at tti: %d (now is %d)\n", current_tti, current_tti_);
      transmitted_tti = current_tti; 
      return true; 
    }
  }
  return false;     
}

int prach::tx_tti() {
  return transmitted_tti; 
}

float prach::get_p0_preamble()
{
  return target_power_dbm; 
}


void prach::send(srslte::radio *radio_handler, float cfo, float pathloss, srslte_timestamp_t tx_time)
{
  
  // Get current TX gain 
  float old_gain = radio_handler->get_tx_gain(); 
  
  // Correct CFO before transmission FIXME: UL SISO Only
  srslte_cfo_correct(&cfo_h, buffer[preamble_idx], signal_buffer, cfo / srslte_symbol_sz(cell.nof_prb));

  // If power control is enabled, choose amplitude and power 
  if (args->ul_pwr_ctrl_en) {
    // Get PRACH transmission power 
    float tx_power = SRSLTE_MIN(SRSLTE_PC_MAX, pathloss + target_power_dbm);
    
    // Get output power for amplitude 1
    radio_handler->set_tx_power(tx_power);
        
    // Scale signal
    float digital_power = srslte_vec_avg_power_cf(signal_buffer, len);
    float scale = sqrtf(pow(10,tx_power/10)/digital_power);
    
    srslte_vec_sc_prod_cfc(signal_buffer, scale, signal_buffer, len);
    log_h->console("PRACH: Pathloss=%.2f dB, Target power %.2f dBm, TX_power %.2f dBm, TX_gain %.1f dB\n",
          pathloss, target_power_dbm, tx_power, radio_handler->get_tx_gain(), scale);
    
  } else {
    float prach_gain = args->prach_gain; 
    if (prach_gain > 0) {
      radio_handler->set_tx_gain(prach_gain);
    }
    Debug("TX PRACH: Power control for PRACH is disabled, setting gain to %.0f dB\n", prach_gain);
  }

  void *tmp_buffer[SRSLTE_MAX_PORTS] = {signal_buffer, NULL, NULL, NULL};
  radio_handler->tx(tmp_buffer, len, tx_time);
  radio_handler->tx_end();
  
  Info("PRACH: Transmitted preamble=%d, CFO=%.2f KHz, tx_time=%f\n", 
       preamble_idx, cfo*15, tx_time.frac_secs);
  preamble_idx = -1;

  radio_handler->set_tx_gain(old_gain);
  Debug("Restoring TX gain to %.0f dB\n", old_gain);  
}
  
} // namespace srsue