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PDCCH unscrambling: correct c_init modulo

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As specified in TS 38.211 Section 7.3.2.3, c_init is the result of a mod
2^31. Before this commit, the code assumed a wrong, implicit mod 2^32,
even though the comment says otherwise.
This commit is contained in:
francescomani
2023-08-02 13:05:08 +02:00
committed by Robert Schmidt
parent 1cbd6c714b
commit 7479597a37
1 changed files with 3 additions and 2 deletions
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openair1/PHY/NR_UE_TRANSPORT/dci_nr.c
+3 -2
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@@ -800,7 +800,8 @@ void nr_pdcch_unscrambling(int16_t *e_rx,
uint16_t scrambling_RNTI, uint16_t scrambling_RNTI,
uint32_t length, uint32_t length,
uint16_t pdcch_DMRS_scrambling_id, uint16_t pdcch_DMRS_scrambling_id,
int16_t *z2) { int16_t *z2)
{
int i; int i;
uint8_t reset; uint8_t reset;
uint32_t x1 = 0, x2 = 0, s = 0; uint32_t x1 = 0, x2 = 0, s = 0;
@@ -809,7 +810,7 @@ void nr_pdcch_unscrambling(int16_t *e_rx,
reset = 1; reset = 1;
// x1 is set in first call to lte_gold_generic // x1 is set in first call to lte_gold_generic
n_id = pdcch_DMRS_scrambling_id; n_id = pdcch_DMRS_scrambling_id;
x2 = ((rnti<<16) + n_id); //mod 2^31 is implicit //this is c_init in 38.211 v15.1.0 Section 7.3.2.3 x2 = ((rnti << 16) + n_id) % (1U << 31); // this is c_init in 38.211 v15.1.0 Section 7.3.2.3
LOG_D(PHY,"PDCCH Unscrambling x2 %x : scrambling_RNTI %x\n", x2, rnti); LOG_D(PHY,"PDCCH Unscrambling x2 %x : scrambling_RNTI %x\n", x2, rnti);