avoid detecting DCI0 at subframes where no DCI0s are sent by eNB. This happens only in TDD mode

issue !156

openair1/PHY/impl_defs_lte.h

@@ -1059,6 +1059,14 @@ typedef enum {
 
 typedef enum {SF_DL, SF_UL, SF_S} lte_subframe_t;
 
-#endif
-
+typedef enum {
+  /// do not detect any DCIs in the current subframe
+  NO_DCI = 0x0,
+  /// detect only downlink DCIs in the current subframe
+  UL_DCI = 0x1,
+  /// detect only uplink DCIs in the current subframe
+  DL_DCI = 0x2,
+  /// detect both uplink and downlink DCIs in the current subframe
+  UL_DL_DCI = 0x3} dci_detect_mode_t;
 
+#endif

openair1/SCHED/defs.h

@@ -212,6 +212,13 @@ void prach_procedures(PHY_VARS_eNB *eNB);
 
 lte_subframe_t subframe_select(LTE_DL_FRAME_PARMS *frame_parms,uint8_t subframe);
 
+/*! \brief Function to compute which type of DCIs to detect in the given subframe
+  @param frame_parms Pointer to DL frame parameter descriptor
+  @param subframe Subframe index
+  @returns DCI detetion mode type (no DCIs, uplink DCIs, downlink DCIs, both uplink and downlink DCIs)
+ */
+dci_detect_mode_t dci_detect_mode_select(LTE_DL_FRAME_PARMS *frame_parms,uint8_t subframe);
+
 /*! \brief Function to compute subframe type as a function of Frame type and TDD Configuration (implements Table 4.2.2 from 36.211, p.11 from version 8.6) and subframe index.  Same as subframe_select, except that it uses the Mod_id and is provided as a service to the MAC scheduler.
   @param Mod_id Index of eNB
   @param CC_id Component Carrier Index

openair1/SCHED/phy_procedures_lte_common.c

@@ -518,6 +518,34 @@ lte_subframe_t subframe_select(LTE_DL_FRAME_PARMS *frame_parms,unsigned char sub
   }
 }
 
+dci_detect_mode_t dci_detect_mode_select(LTE_DL_FRAME_PARMS *frame_parms,uint8_t subframe)
+{
+  dci_detect_mode_t ret = 0;
+
+  static dci_detect_mode_t Table_8_2_3gpp_36_213[][10] = {
+     //subf0    , subf1     , subf2 , subf3         , subf4     , subf5     , subf6     , subf7 , subf8     , subf9
+      {UL_DL_DCI, UL_DL_DCI , NO_DCI    , NO_DCI    , NO_DCI    , UL_DL_DCI , UL_DL_DCI , NO_DCI, NO_DCI    , NO_DCI    },  // tdd0
+      {DL_DCI   , UL_DL_DCI , NO_DCI    , NO_DCI    , UL_DL_DCI , DL_DCI    , UL_DL_DCI , NO_DCI, NO_DCI    , UL_DL_DCI },  // tdd1
+      {DL_DCI   , DL_DCI    , NO_DCI    , UL_DL_DCI , DL_DCI    , DL_DCI    , DL_DCI    , NO_DCI, UL_DL_DCI , DL_DCI    },  // tdd2
+      {UL_DL_DCI, DL_DCI    , NO_DCI    , NO_DCI    , NO_DCI    , DL_DCI    , DL_DCI    , DL_DCI, UL_DL_DCI , UL_DL_DCI },  // tdd3
+      {DL_DCI   , DL_DCI    , NO_DCI    , NO_DCI    , DL_DCI    , DL_DCI    , DL_DCI    , DL_DCI, UL_DL_DCI , UL_DL_DCI },  // tdd4
+      {DL_DCI   , DL_DCI    , NO_DCI    , DL_DCI    , DL_DCI    , DL_DCI    , DL_DCI    , DL_DCI, UL_DL_DCI , DL_DCI    },  // tdd5
+      {UL_DL_DCI, UL_DL_DCI , NO_DCI    , NO_DCI    , NO_DCI    , UL_DL_DCI , UL_DL_DCI , NO_DCI, NO_DCI    , UL_DL_DCI }}; // tdd6
+
+
+  DevAssert(subframe>=0 && subframe<=9);
+  DevAssert((frame_parms->tdd_config)>=0 && (frame_parms->tdd_config)<=6);
+
+  if (frame_parms->frame_type == FDD) {
+    ret = UL_DL_DCI;
+  } else {
+    ret = Table_8_2_3gpp_36_213[frame_parms->tdd_config][subframe];
+  }
+
+  LOG_D(PHY, "subframe %d: detect UL_DCI=%d, detect DL_DCI=%d\n", subframe, (ret & UL_DCI)>0, (ret & DL_DCI)>0);
+  return ret;
+}
+
 lte_subframe_t get_subframe_direction(uint8_t Mod_id,uint8_t CC_id,uint8_t subframe)
 {