From 4f43935dd3815767c8223a1d9d38b175ae091e6a Mon Sep 17 00:00:00 2001
From: Xavier Arteaga <xavier@softwareradiosystems.com>
Date: Wed, 3 Feb 2021 11:06:01 +0100
Subject: [PATCH] NR-SCH: CRC is KO if data is all zeros

---
 lib/src/phy/phch/sch_nr.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/src/phy/phch/sch_nr.c b/lib/src/phy/phch/sch_nr.c
index 045df37c1..ae31e13f9 100644
--- a/lib/src/phy/phch/sch_nr.c
+++ b/lib/src/phy/phch/sch_nr.c
@@ -639,9 +639,15 @@ int sch_nr_decode(srslte_sch_nr_t*        q,
       }
     }
 
+    // Check if TB is all zeros
+    bool all_zeros = true;
+    for (uint32_t i = 0; i < tb->tbs && all_zeros; i++) {
+      all_zeros = (data[i] == 0);
+    }
+
     // Calculate TB CRC from packed data
     uint32_t checksum1 = srslte_crc_checksum_byte(cfg.crc_tb, data, tb->tbs);
-    *crc_ok            = (checksum1 == checksum2);
+    *crc_ok            = (checksum1 == checksum2 && !all_zeros);
 
     SCH_INFO_RX("TB: TBS=%d; CRC={%06x, %06x}\n", tb->tbs, checksum1, checksum2);
     if (SRSLTE_DEBUG_ENABLED && srslte_verbose >= SRSLTE_VERBOSE_DEBUG && !handler_registered) {