From fc3e9f0efe8ce43c9582dc8809d7ce68657bf1ad Mon Sep 17 00:00:00 2001
From: Bartosz Podrygajlo <bartosz.podrygajlo@openairinterface.org>
Date: Wed, 16 Apr 2025 17:41:02 +0200
Subject: [PATCH] UE TX time budget

Measure the UEs TX time budget and warn if its violated.
---
 executables/nr-ue.c       | 33 +++++++++++++++++++++++++++++++++
 openair1/PHY/defs_nr_UE.h |  1 +
 2 files changed, 34 insertions(+)

diff --git a/executables/nr-ue.c b/executables/nr-ue.c
index 1939c4175b..8849dad1b5 100644
--- a/executables/nr-ue.c
+++ b/executables/nr-ue.c
@@ -43,6 +43,7 @@
 #include "position_interface.h"
 #include "nr_phy_common.h"
 #include "common/utils/time_manager/time_manager.h"
+#include "log.h"
 
 /*
  *  NR SLOT PROCESSING SEQUENCE
@@ -545,6 +546,28 @@ static void RU_write(nr_rxtx_thread_data_t *rxtxD, bool sl_tx_action, c16_t **tx
     }
   }
 
+  if (!IS_SOFTMODEM_RFSIM) {
+    uint64_t deadline_us = rxtxD->absolute_deadline_us;
+    struct timespec current_time;
+    if (clock_gettime(CLOCK_REALTIME, &current_time)) {
+      LOG_E(PHY, "clock_gettime failed\n");
+    }
+    uint64_t current_time_us = current_time.tv_sec * 1e6 + current_time.tv_nsec / 1e3;
+    if (current_time_us > deadline_us) {
+      static unsigned int deadline_warning_rate_limit = 0;
+      if (deadline_warning_rate_limit % 1000 == 0) {
+        LOG_W(PHY,
+              "Deadline missed for tx slot %d.%d (current time %lu us, deadline %lu us, missed by %lu)\n",
+              proc->frame_tx,
+              proc->nr_slot_tx,
+              current_time_us,
+              deadline_us,
+              current_time_us - deadline_us);
+      }
+      deadline_warning_rate_limit++;
+    }
+  }
+
   openair0_timestamp writeTimestamp = proc->timestamp_tx;
   int writeBlockSize = rxtxD->writeBlockSize;
   // if writeBlockSize gets longer that slot size, fill with dummy
@@ -1140,6 +1163,10 @@ void *UE_thread(void *arg)
     int tmp = UE->rfdevice.trx_read_func(&UE->rfdevice, &rx_timestamp, rxp, readBlockSize, fp->nb_antennas_rx);
     UEscopeCopy(UE, ueTimeDomainSamples, rxp[0], sizeof(c16_t), 1, readBlockSize, 0);
     AssertFatal(readBlockSize == tmp, "");
+    struct timespec current_time;
+    if (clock_gettime(CLOCK_REALTIME, &current_time)) {
+      LOG_E(PHY, "clock_gettime failed\n");
+    }
 
     if(slot_nr == (nb_slot_frame - 1)) {
       // read in first symbol of next frame and adjust for timing drift
@@ -1162,6 +1189,11 @@ void *UE_thread(void *arg)
     const openair0_timestamp writeTimestamp = rx_timestamp + fp->get_samples_slot_timestamp(slot_nr, fp, duration_rx_to_tx)
                                               - firstSymSamp - UE->N_TA_offset - timing_advance;
 
+    // Calculate TX deadline, approximately 1 symbol before the first sample should be written
+    const uint64_t samples_diff = writeTimestamp - rx_timestamp - fp->ofdm_symbol_size;
+    const float deadline_us = samples_diff / UE->rfdevice.openair0_cfg->sample_rate * 1e6;
+    const uint64_t absolute_deadline_us = current_time.tv_sec * 1e6 + current_time.tv_nsec / 1e3 + deadline_us;
+
     // but use current UE->timing_advance value to compute writeBlockSize
     int writeBlockSize = fp->get_samples_per_slot((slot_nr + duration_rx_to_tx) % nb_slot_frame, fp) - iq_shift_to_apply;
     int new_timing_advance = UE->timing_advance;
@@ -1204,6 +1236,7 @@ void *UE_thread(void *arg)
     curMsgTx->writeBlockSize = writeBlockSize;
     curMsgTx->proc.timestamp_tx = writeTimestamp;
     curMsgTx->UE = UE;
+    curMsgTx->absolute_deadline_us = absolute_deadline_us;
 
     int slot = curMsgTx->proc.nr_slot_tx;
     int slot_and_frame = slot + curMsgTx->proc.frame_tx * UE->frame_parms.slots_per_frame;
diff --git a/openair1/PHY/defs_nr_UE.h b/openair1/PHY/defs_nr_UE.h
index db8524eddd..9d8683481d 100644
--- a/openair1/PHY/defs_nr_UE.h
+++ b/openair1/PHY/defs_nr_UE.h
@@ -598,6 +598,7 @@ typedef struct nr_rxtx_thread_data_s {
   int writeBlockSize;
   nr_phy_data_t phy_data;
   dynamic_barrier_t* next_barrier;
+  uint64_t absolute_deadline_us;
 } nr_rxtx_thread_data_t;
 
 typedef struct LDPCDecode_ue_s {