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  {
   "cell_type": "markdown",
   "id": "efc46b98-fcfb-4a29-a48e-feadc09bb093",
   "metadata": {},
   "source": [
    "# TDL Channel\n",
    "This notebook shows how to use a TDL channel in time and frequency domains."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "95faa819-986f-498a-8204-2a372fb70c70",
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import scipy.io\n",
    "import time\n",
    "\n",
    "from neoradium import Carrier, Modem, TdlChannel, Grid, random\n",
    "from neoradium.utils import getNmse"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "6852bf87-ada1-4c5b-a7c4-b75a100d638d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Shape of Resource Grid: (8, 14, 300)\n",
      "Shape of Waveform:      (8, 30720)\n"
     ]
    }
   ],
   "source": [
    "# Create a valid random grid\n",
    "random.setSeed(123)                                    # Make results reproducible\n",
    "carrier = Carrier(startRb=0, numRbs=25, spacing=15)    # Carrier 25 Resource Blocks, 15KHz subcarrier spacing\n",
    "bwp = carrier.curBwp                                   # The only bandwidth part in the carrier\n",
    "txGrid = bwp.createGrid(numPlanes=8)                   # Create an empty resource grid\n",
    "\n",
    "stats = txGrid.getStats()                              # Get statistics about the grid\n",
    "modem = Modem(\"16QAM\")                                 # Using 16QAM modulation\n",
    "numRandomBits = stats['UNASSIGNED']*modem.qm           # Total number of bits available in the resource grid\n",
    "\n",
    "bits = random.bits(numRandomBits)                      # Create random bits\n",
    "symbols = modem.modulate(bits)                         # Modulate the bits to get symbols\n",
    "\n",
    "indexes = txGrid.getReIndexes(\"UNASSIGNED\")            # Indexes of the \"UNASSIGNED\" resources\n",
    "txGrid[indexes] = symbols                              # Put symbols in the resource grid\n",
    "\n",
    "txWaveform = txGrid.ofdmModulate()                     # OFDM-Modulate the resource grid to get a waveform\n",
    "\n",
    "print(\"Shape of Resource Grid:\",txGrid.shape)\n",
    "print(\"Shape of Waveform:     \",txWaveform.shape)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "d9fcd860-1480-4c68-9b5b-62d14db2b6e4",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "TDL-D Channel Properties:\n",
      "  carrierFreq:      4 GHz\n",
      "  normalizeGains:   True\n",
      "  normalizeOutput:  True\n",
      "  txDir:            Downlink\n",
      "  filterLen:        16 samples\n",
      "  delayQuantSize:   64\n",
      "  stopBandAtten:    80 db\n",
      "  dopplerShift:     50 Hz\n",
      "  coherenceTime:    8.463 milliseconds\n",
      "  delaySpread:      30 ns\n",
      "  pathDelays (ns):  0.0000 1.0500 18.360 40.890 42.150 54.120 77.880 53.250 121.26 238.11\n",
      "                    282.72 291.24 375.75\n",
      "  pathPowers (db):  -0.001 -18.80 -21.00 -22.80 -17.90 -20.10 -21.90 -22.90 -27.80 -23.60\n",
      "                    -24.80 -30.00 -27.70\n",
      "  hasLOS:           True\n",
      "  kFactorLos (db):  13.300\n",
      "  rxAntennaCount:   2\n",
      "  txAntennaCount:   8\n",
      "  mimoCorrelation:  Medium\n",
      "  polarization:     CoPolar\n",
      "  sosType:          GMEDS1\n",
      "  sosNumSins:       32\n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Create a TDL-D channel model with 4GHz carrier frequency, and 50Hz doppler shift\n",
    "channel = TdlChannel(bwp, 'D', carrierFreq=4e9, dopplerShift=50,\n",
    "                     txAntennaCount=8, rxAntennaCount=2, mimoCorrelation='Medium')\n",
    "print(channel)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "17c876c9-9ec1-47af-a4c5-09dcbc143ade",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Time to apply channel in Freq. Domain: 0.004817008972167969\n"
     ]
    }
   ],
   "source": [
    "# Apply the channel in Frequency Domain:\n",
    "t0 =time.time()\n",
    "channelMatrix = channel.getChannelMatrix()\n",
    "rxGridF = txGrid.applyChannel(channelMatrix)\n",
    "t1 =time.time()\n",
    "print(\"Time to apply channel in Freq. Domain:\", t1-t0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "f0d833cd-82f7-4721-a81a-941ca7e980f2",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Time to apply channel in Time Domain: 0.09486007690429688\n",
      "NMSE between the rxGrid in Time and Freq. domains:  6.26924445685763e-17\n"
     ]
    }
   ],
   "source": [
    "# Applying the channel in time domain and demodulate to get a received resource grid (rxGrid)\n",
    "t0 =time.time()\n",
    "maxDelay = channel.getMaxDelay()                         # Calculate the channel's max delay\n",
    "paddedTxWaveform = txWaveform.pad(maxDelay)              # Pad the waveform with zeros\n",
    "rxWaveform = channel.applyToSignal(paddedTxWaveform)     # Apply the channel to the waveform\n",
    "offset = channel.getTimingOffset()                       # Get the timing offset for synchronization\n",
    "syncedWaveform = rxWaveform.sync(offset)                 # Synchronization\n",
    "rxGridT = Grid.ofdmDemodulate(bwp, syncedWaveform)       # OFDM-demodulation\n",
    "t1 =time.time()\n",
    "print(\"Time to apply channel in Time Domain:\", t1-t0)\n",
    "print(\"NMSE between the rxGrid in Time and Freq. domains: \", getNmse(rxGridT.grid,rxGridF.grid)) \n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3b83e1e2-a7e9-4439-8712-82fb67ca0b3f",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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