From 58aac96a6e0597615fab0c18db56b1ee383d8a43 Mon Sep 17 00:00:00 2001
From: Xavier Arteaga <xavier@softwareradiosystems.com>
Date: Tue, 21 Nov 2017 16:11:08 +0100
Subject: [PATCH] Added Power Allocation from HL in UE side

---
 lib/include/srslte/phy/phch/pdsch_cfg.h |  7 +++++++
 lib/src/phy/ue/ue_dl.c                  | 28 ++++++++++++++++++++++++-
 srsue/src/phy/phch_worker.cc            |  9 ++++++--
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/lib/include/srslte/phy/phch/pdsch_cfg.h b/lib/include/srslte/phy/phch/pdsch_cfg.h
index 63b3fefcc..569d1ef7e 100644
--- a/lib/include/srslte/phy/phch/pdsch_cfg.h
+++ b/lib/include/srslte/phy/phch/pdsch_cfg.h
@@ -39,6 +39,13 @@
 #include "srslte/phy/fec/softbuffer.h"
 #include "srslte/phy/fec/cbsegm.h"
 
+/* 3GPP 36.213 Table 5.2-1: The cell-specific ratio rho_B / rho_A for 1, 2, or 4 cell specific antenna ports */
+static const float pdsch_cfg_cell_specific_ratio_table[2][4] =
+    { /* One antenna port         */ {1.0f / 1.0f, 4.0f / 5.0f, 3.0f / 5.0f, 2.0f / 5.0f},
+      /* Two or more antenna port */ {5.0f / 4.0f, 1.0f / 1.0f, 3.0f / 4.0f, 1.0f / 2.0f}
+    };
+
+
 typedef struct SRSLTE_API {
   srslte_cbsegm_t cb_segm[SRSLTE_MAX_CODEWORDS];
   srslte_ra_dl_grant_t grant;
diff --git a/lib/src/phy/ue/ue_dl.c b/lib/src/phy/ue/ue_dl.c
index 137756da1..494eecba7 100644
--- a/lib/src/phy/ue/ue_dl.c
+++ b/lib/src/phy/ue/ue_dl.c
@@ -308,10 +308,36 @@ void srslte_ue_dl_set_non_mbsfn_region(srslte_ue_dl_t *q,
   srslte_ofdm_set_non_mbsfn_region(&q->fft_mbsfn, non_mbsfn_region_length);
 }
 
-void srslte_ue_dl_set_power_alloc (srslte_ue_dl_t *q, float rho_a, float rho_b) {
+void srslte_ue_dl_set_power_alloc(srslte_ue_dl_t *q, float rho_a, float rho_b) {
   if (q) {
     srslte_pdsch_set_power_allocation(&q->pdsch, rho_a);
     q->rho_b = rho_b;
+
+    uint32_t nof_symbols_slot = SRSLTE_CP_NSYMB(q->cell.cp);
+    uint32_t nof_re_symbol = SRSLTE_NRE * q->cell.nof_prb;
+
+    /* Apply rho_b if required according to 3GPP 36.213 Table 5.2-2 */
+    if (rho_b != 0.0f && rho_b != 1.0f) {
+      float scaling = 1.0f / rho_b;
+      for (uint32_t i = 0; i < q->nof_rx_antennas; i++) {
+        for (uint32_t j = 0; j < 2; j++) {
+          cf_t *ptr;
+          ptr = q->sf_symbols_m[i] + nof_re_symbol * (j * nof_symbols_slot + 0);
+          srslte_vec_sc_prod_cfc(ptr, scaling, ptr, nof_re_symbol);
+          if (q->cell.cp == SRSLTE_CP_NORM) {
+            ptr = q->sf_symbols_m[i] + nof_re_symbol * (j * nof_symbols_slot + 4);
+            srslte_vec_sc_prod_cfc(ptr, scaling, ptr, nof_re_symbol);
+          } else {
+            ptr = q->sf_symbols_m[i] + nof_re_symbol * (j * nof_symbols_slot + 3);
+            srslte_vec_sc_prod_cfc(ptr, scaling, ptr, nof_re_symbol);
+          }
+          if (q->cell.nof_ports == 4) {
+            ptr = q->sf_symbols_m[i] + nof_re_symbol * (j * nof_symbols_slot + 1);
+            srslte_vec_sc_prod_cfc(ptr, scaling, ptr, nof_re_symbol);
+          }
+        }
+      }
+    }
   }
 }
 
diff --git a/srsue/src/phy/phch_worker.cc b/srsue/src/phy/phch_worker.cc
index 529dd92f2..7b4ec48bd 100644
--- a/srsue/src/phy/phch_worker.cc
+++ b/srsue/src/phy/phch_worker.cc
@@ -601,11 +601,16 @@ int phch_worker::decode_pdsch(srslte_ra_dl_grant_t *grant, uint8_t *payload[SRSL
       valid_config = false;
   }
 
-  /* Set power allocation */
+  /* Set power allocation according to 3GPP 36.213 clause 5.2 Downlink power allocation */
   float rho_a = 1.0f, rho_b = 1.0f;
   if (phy->config->dedicated.pdsch_cnfg_ded < LIBLTE_RRC_PDSCH_CONFIG_P_A_N_ITEMS) {
     float rho_a_db = liblte_rrc_pdsch_config_p_a_num[(int) phy->config->dedicated.pdsch_cnfg_ded];
-    rho_a = powf(10.0f, rho_a_db / 20.0f) * sqrtf(2.0f);
+    rho_a = powf(10.0f, rho_a_db / 20.0f) * ((cell.nof_ports == 1) ? 1.0f : sqrtf(2.0f));
+  }
+  if (phy->config->common.pdsch_cnfg.p_b < 4) {
+    uint32_t idx0 = (cell.nof_ports == 1) ? 0 : 1;
+    float cell_specific_ratio = pdsch_cfg_cell_specific_ratio_table[idx0][phy->config->common.pdsch_cnfg.p_b];
+    rho_b = sqrtf(cell_specific_ratio);
   }
   srslte_ue_dl_set_power_alloc(&ue_dl, rho_a, rho_b);