Harald Welte has submitted this change and it was merged. (
https://gerrit.osmocom.org/9994 )
Change subject: coding: Fix (E)GPRS BER calculation to correctly account for
puncturing.
......................................................................
coding: Fix (E)GPRS BER calculation to correctly account for puncturing.
Previously we didn't take into account puncturing and BER was always around
30% for GPRS/EDGE bursts because of they use puncturing coding unlike
"classical" GSM bursts.
Change-Id: I9da22e7051522d06d923fcec3b63cbed8db93910
---
M src/coding/gsm0503_coding.c
1 file changed, 24 insertions(+), 5 deletions(-)
Approvals:
Jenkins Builder: Verified
Vadim Yanitskiy: Looks good to me, but someone else must approve
Harald Welte: Looks good to me, approved
diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 215cc6d..1d06adb 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -528,16 +528,18 @@
},
};
-/*! Convolutional Decode + compute BER
+/*! Convolutional Decode + compute BER for punctured codes
* \param[in] code Description of Convolutional Code
* \param[in] input Input soft-bits (-127...127)
* \param[out] output bits
* \param[out] n_errors Number of bit-errors
* \param[out] n_bits_total Number of bits
+ * \param[in] data_punc Puncturing mask array. Can be NULL.
*/
-static int osmo_conv_decode_ber(const struct osmo_conv_code *code,
+static int osmo_conv_decode_ber_punctured(const struct osmo_conv_code *code,
const sbit_t *input, ubit_t *output,
- int *n_errors, int *n_bits_total)
+ int *n_errors, int *n_bits_total,
+ const uint8_t *data_punc)
{
int res, i, coded_len;
ubit_t recoded[EGPRS_DATA_C_MAX];
@@ -553,7 +555,8 @@
if (n_errors) {
*n_errors = 0;
for (i = 0; i < coded_len; i++) {
- if (!((recoded[i] && input[i] < 0) ||
+ if (((!data_punc) || (data_punc && !data_punc[i])) &&
+ !((recoded[i] && input[i] < 0) ||
(!recoded[i] && input[i] > 0)) )
*n_errors += 1;
}
@@ -565,6 +568,21 @@
return res;
}
+/*! Convolutional Decode + compute BER for non-punctured codes
+ * \param[in] code Description of Convolutional Code
+ * \param[in] input Input soft-bits (-127...127)
+ * \param[out] output bits
+ * \param[out] n_errors Number of bit-errors
+ * \param[out] n_bits_total Number of bits
+ */
+static int osmo_conv_decode_ber(const struct osmo_conv_code *code,
+ const sbit_t *input, ubit_t *output,
+ int *n_errors, int *n_bits_total)
+{
+ return osmo_conv_decode_ber_punctured(code, input, output,
+ n_errors, n_bits_total, NULL);
+}
+
/*! convenience wrapper for decoding coded bits
* \param[out] l2_data caller-allocated buffer for L2 Frame
* \param[in] cB 456 coded (soft) bits as per TS 05.03 4.1.3
@@ -884,7 +902,8 @@
C[i] = 0;
}
- osmo_conv_decode_ber(code->data_conv, C, u, n_errors, n_bits_total);
+ osmo_conv_decode_ber_punctured(code->data_conv, C, u,
+ n_errors, n_bits_total, code->data_punc[p]);
rc = osmo_crc16gen_check_bits(&gsm0503_mcs_crc12, u,
data_len, u + data_len);
if (rc)
--
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Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I9da22e7051522d06d923fcec3b63cbed8db93910
Gerrit-Change-Number: 9994
Gerrit-PatchSet: 1
Gerrit-Owner: Alexander Chemeris <[email protected]>
Gerrit-Reviewer: Alexander Chemeris <[email protected]>
Gerrit-Reviewer: Harald Welte <[email protected]>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Vadim Yanitskiy <[email protected]>
