Rfsim: Process received packets on demand

- Received packets are dynamically allocated and kept in a
queue for as long as they are needed.

- The layout of the packets was changed from interleaved antennas
to non-interleaved antennas.

- Generate a contiguous buffer from saved packets as needed.

There is extra work caused by this change due to recv() call no
longer saving data directly into the circular buffer, however further
processing is easier due to contiguous nature of the tx antenna buffers
prepared. The impact on performance was not measured.

radio/rfsimulator/apply_channelmod.c

@@ -41,14 +41,12 @@
   either we regenerate the channel (call again random_channel(desc,0)), or we keep it over subframes
   legacy: we regenerate each sub frame in UL, and each frame only in DL
 */
-void rxAddInput(const c16_t *input_sig,
+void rxAddInput(const c16_t **input_sig,
                 cf_t *after_channel_sig,
                 int rxAnt,
                 channel_desc_t *channelDesc,
                 int nbSamples,
-                uint64_t TS,
-                uint32_t CirSize,
-                bool add_noise)
+                uint64_t TS)
 {
   static uint64_t last_TS = 0;
 
@@ -249,8 +247,7 @@ void rxAddInput(const c16_t *input_sig,
   const double pathLossLinear = pow(10, channelDesc->path_loss_dB / 20.0);
   // Energy in one sample to calibrate input noise
   // the normalized OAI value seems to be 256 as average amplitude (numerical amplification = 1)
-  const double noise_per_sample = add_noise ? pow(10, channelDesc->noise_power_dB / 10.0) * 256 : 0;
-  const uint64_t dd = channelDesc->channel_offset;
+  const double noise_per_sample = pow(10, channelDesc->noise_power_dB / 10.0) * 256;
   const int nbTx = channelDesc->nb_tx;
   double Doppler_phase_cur = channelDesc->Doppler_phase_cur[rxAnt];
   Doppler_phase_cur -= 2 * M_PI * round(Doppler_phase_cur / (2 * M_PI));
@@ -264,15 +261,8 @@ void rxAddInput(const c16_t *input_sig,
 
       // const struct complex *channelModelEnd=channelModel+channelDesc->channel_length;
       for (int l = 0; l < (int)channelDesc->channel_length; l++) {
-        // let's assume TS+i >= l
-        // fixme: the rfsimulator current structure is interleaved antennas
-        // this has been designed to not have to wait a full block transmission
-        // but it is not very usefull
-        // it would be better to split out each antenna in a separate flow
-        // that will allow to mix ru antennas freely
-        // (X + cirSize) % cirSize to ensure that index is positive
-        const int idx = ((TS + i - l - dd) * nbTx + txAnt + CirSize) % CirSize;
-        const struct complex16 tx16 = input_sig[idx];
+        const int idx = i - l + channelDesc->channel_length - 1;
+        const struct complex16 tx16 = input_sig[txAnt][idx];
         rx_tmp.r += tx16.r * channelModel[l].r - tx16.i * channelModel[l].i;
         rx_tmp.i += tx16.i * channelModel[l].r + tx16.r * channelModel[l].i;
       } // l
@@ -297,11 +287,10 @@ void rxAddInput(const c16_t *input_sig,
 
   channelDesc->Doppler_phase_cur[rxAnt] = Doppler_phase_cur;
 
-  if ((TS * nbTx) % CirSize + nbSamples <= CirSize)
   // Cast to a wrong type for compatibility !
   LOG_D(HW,
         "Input power %f, output power: %f, channel path loss %f, noise coeff: %f \n",
-          10 * log10((double)signal_energy((int32_t *)&input_sig[(TS * nbTx) % CirSize], nbSamples)),
+        10 * log10((double)signal_energy((int32_t *)&input_sig[0], nbSamples)),
         10 * log10((double)signal_energy((int32_t *)after_channel_sig, nbSamples)),
         channelDesc->path_loss_dB,
         10 * log10(noise_per_sample));

radio/rfsimulator/rfsimulator.h

@@ -24,13 +24,11 @@
 #ifndef __RFSIMULATOR_H
 #define __RFSIMULATOR_H
 #include <stdbool.h>
-void rxAddInput(const c16_t *input_sig,
+void rxAddInput(const c16_t **input_sig,
                 cf_t *after_channel_sig,
                 int rxAnt,
                 channel_desc_t *channelDesc,
                 int nbSamples,
-                uint64_t TS,
-                uint32_t CirSize,
-                bool apply_noise);
+                uint64_t TS);
 
 #endif