Phy Class Reference

The PHY component. More...

#include <Phy.h>

Classes
struct	mch_info_t
struct	mtch_info_t

Public Types
enum	SubcarrierSpacing { df_15kHz, df_7kHz5, df_1kHz25 }
typedef std::function< int(cf_t *data, uint32_t nsamples, srslte_timestamp_t *rx_time)>	get_samples_t
	Definition of the callback function used to fetch samples from the SDR.

Public Member Functions
	Phy (const libconfig::Config &cfg, get_samples_t cb, uint8_t cs_nof_prb, int8_t override_nof_prb)
	Default constructor. More...
virtual	~Phy ()
	Default destructor.
bool	init ()
	Initialize the underlying components.
bool	cell_search ()
	Search for a cell. More...
bool	synchronize_subframe ()
	Synchronizes PSS/SSS and tries to deocode the MIB. More...
bool	get_next_frame (cf_t **buffer, uint32_t size)
	Get the sample data for the next subframe.
srslte_cell_t	cell ()
	Get the current cell (with params adjusted for MBSFN)
unsigned	nr_prb ()
	Get the current number of PRB.
uint32_t	tti ()
	Get the current subframe TTI.
float	cfo ()
	Get the current CFO value.
void	set_cfo_from_channel_estimation (float cfo)
	Set the CFO value from channel estimation.
void	set_mch_scheduling_info (const srslte::sib13_t &sib13)
	Set the values received in SIB13.
void	set_mbsfn_config (const srslte::mcch_msg_t &mcch)
	Set MBSFN configuration values.
void	reset ()
	Clear configuration values.
bool	mcch_configured ()
	Return true if MCCH has been configured.
uint8_t	mbsfn_area_id ()
	Returns the current MBSFN area ID.
srslte_mbsfn_cfg_t	mbsfn_config_for_tti (uint32_t tti, unsigned &area)
	Returns the MBSFN configuration (MCS, etc) for the subframe with the passed TTI.
void	set_decode_mcch (bool d)
	Enable MCCH decoding.
uint8_t	nof_mbsfn_prb ()
	Get number of PRB in MBSFN/PMCH.
void	set_cell ()
const std::vector< mch_info_t > &	mch_info ()
void	set_dest_for_lcid (int lcid, std::string dest)
SubcarrierSpacing	mbsfn_subcarrier_spacing ()
float	mbsfn_subcarrier_spacing_khz ()
srslte::mcch_msg_t &	mcch ()

Public Attributes
int	_mcs = 0
get_samples_t	_sample_cb

Detailed Description

The PHY component.

Handles synchronisation and is the central hub for lower level processing

Definition at line 43 of file Phy.h.

Constructor & Destructor Documentation

Phy()

Phy::Phy	(	const libconfig::Config &	cfg,
		get_samples_t	cb,
		uint8_t	cs_nof_prb,
		int8_t	override_nof_prb
	)

Default constructor.

Parameters

cfg	Config singleton reference
cb	Sample recv callback
cs_nof_prb	Nr of PRBs to use during cell search
override_nof_prb	If set, overrides the nof PRB received in the MIB

Definition at line 40 of file Phy.cpp.

    : _cfg(cfg),
      _sample_cb(std::move(std::move(cb))),
      _cs_nof_prb(cs_nof_prb),
      _override_nof_prb(override_nof_prb) {
  _buffer_max_samples = kMaxBufferSamples;
  _mib_buffer[0] = static_cast<cf_t*>(malloc(_buffer_max_samples * sizeof(cf_t)));  // NOLINT
}

Member Function Documentation

cell_search()

auto Phy::cell_search

(

)

Search for a cell.

Returns true if a cell has been found and the MIB could be decoded, false otherwise.

Definition at line 82 of file Phy.cpp.

                              {
  std::array<srslte_ue_cellsearch_result_t, kMaxCellsToDiscover> found_cells = {0};
 
  uint32_t max_peak_cell = 0;
  int ret = srslte_ue_cellsearch_scan(&_cell_search, found_cells.data(), &max_peak_cell);
  if (ret < 0) {
    spdlog::error("Phy: Error decoding MIB: Error searching PSS\n");
    return false;
  }
  if (ret == 0) {
    spdlog::error("Phy: Could not find any cell in this frequency\n");
    return false;
  }
 
  srslte_cell_t new_cell = {};
  new_cell.id         = found_cells.at(max_peak_cell).cell_id;
  new_cell.cp         = found_cells.at(max_peak_cell).cp;
  new_cell.frame_type = found_cells.at(max_peak_cell).frame_type;
  new_cell.mbms_dedicated = true;
  float cfo           = found_cells.at(max_peak_cell).cfo;
 
  spdlog::info("Phy: PSS/SSS detected: Mode {}, PCI {}, CFO {} KHz, CP {}",
               new_cell.frame_type != 0U ? "TDD" : "FDD", new_cell.id,
               cfo / 1000, srslte_cp_string(new_cell.cp));
 
  if (srslte_ue_mib_sync_set_cell_prb(&_mib_sync, new_cell, _cs_nof_prb) != 0) {
    spdlog::error("Phy: Error setting UE MIB sync cell");
    return false;
  }
 
  srslte_ue_sync_reset(&_mib_sync.ue_sync);
 
  std::array<uint8_t, SRSLTE_BCH_PAYLOAD_LEN> bch_payload = {};
  /* Find and decode MIB */
  int sfn_offset = 0;
  ret = srslte_ue_mib_sync_decode_prb(&_mib_sync, 40, bch_payload.data(), &new_cell.nof_ports, &sfn_offset, _cs_nof_prb);
  if (ret == 1) {
    uint32_t sfn = 0;
    srslte_pbch_mib_mbms_unpack(bch_payload.data(), &new_cell, &sfn, nullptr,
                                _override_nof_prb);
 
    spdlog::info(
        "Phy: MIB Decoded. Mode {}, PCI {}, PRB {}, Ports {}, CFO {} KHz, SFN "
        "{}\n",
        new_cell.frame_type != 0u ? "TDD" : "FDD", new_cell.id,
        new_cell.nof_prb, new_cell.nof_ports, cfo / 1000, sfn);
 
    if (!srslte_cell_isvalid(&new_cell)) {
      spdlog::error("SYNC:  Detected invalid cell.\n");
      return false;
    }
 
    _cell = new_cell;
    _cell.mbsfn_prb = _cell.nof_prb;
 
    if (srslte_ue_sync_set_cell(&_ue_sync, cell()) != 0) {
      spdlog::error("Phy: failed to set cell.\n");
      return false;
    }
    if (srslte_ue_mib_set_cell(&_mib, cell()) != 0) {
      spdlog::error("Phy: Error setting UE MIB cell");
      return false;
    }
 
    return true;
  }
 
  spdlog::error("Phy: failed to receive MIB\n");
  return false;
}

synchronize_subframe()

auto Phy::synchronize_subframe

(

)

Synchronizes PSS/SSS and tries to deocode the MIB.

Returns true on success, false otherwise.

Definition at line 55 of file Phy.cpp.

                                       {
 
  int ret = srslte_ue_sync_zerocopy(&_ue_sync, _mib_buffer, _buffer_max_samples);  // NOLINT
  if (ret < 0) {
    spdlog::error("SYNC:  Error calling ue_sync_get_buffer.\n");
    return false;
  }
 
  if (ret == 1) {
    std::array<uint8_t, SRSLTE_BCH_PAYLOAD_LEN> bch_payload = {};
    if (srslte_ue_sync_get_sfidx(&_ue_sync) == 0) {
      int sfn_offset = 0;
      int n =
          srslte_ue_mib_decode(&_mib, bch_payload.data(), nullptr, &sfn_offset);
      if (n == 1) {
        uint32_t sfn = 0;
        srslte_pbch_mib_mbms_unpack(bch_payload.data(), &_cell, &sfn, nullptr,
                                    _override_nof_prb);
        sfn = (sfn + sfn_offset * kSfnOffset) % kMaxSfn;
        _tti = sfn * kSubframesPerFrame;
        return true;
      }
    }
  }
  return false;
}

---

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

• src/Phy.h
• src/Phy.cpp