fixeria has uploaded this change for review.
coding: implement encoding/decoding for TCH/F2.4
See 3GPP TS 45.003 section 3.6. This channel mode is a bit special,
because unlike the other CSD specific channel modes it's interleaved
over 8 (not 22!) consecutive bursts, just like TCH/FS.
Change-Id: I4685376c8deb04db670684c9ebf685ad6fc989fa
Related: OS#1572
---
M include/osmocom/coding/gsm0503_coding.h
M src/coding/gsm0503_coding.c
M src/coding/libosmocoding.map
M tests/coding/coding_test.c
M tests/coding/coding_test.ok
5 files changed, 97 insertions(+), 1 deletion(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/50/33650/1
diff --git a/include/osmocom/coding/gsm0503_coding.h b/include/osmocom/coding/gsm0503_coding.h
index 75e12e6..13d5344 100644
--- a/include/osmocom/coding/gsm0503_coding.h
+++ b/include/osmocom/coding/gsm0503_coding.h
@@ -101,6 +101,10 @@
int gsm0503_tch_hr48_decode(ubit_t *data, const sbit_t *bursts,
int *n_errors, int *n_bits_total);
+int gsm0503_tch_fr24_encode(ubit_t *bursts, const ubit_t *data);
+int gsm0503_tch_fr24_decode(ubit_t *data, const sbit_t *bursts,
+ int *n_errors, int *n_bits_total);
+
int gsm0503_tch_hr24_encode(ubit_t *bursts, const ubit_t *data);
int gsm0503_tch_hr24_decode(ubit_t *data, const sbit_t *bursts,
int *n_errors, int *n_bits_total);
diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 3faa512..0e7f689 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -3472,6 +3472,54 @@
return gsm0503_tch_fr96_decode(data, bursts, n_errors, n_bits_total);
}
+/*! Perform channel encoding of a TCH/F2.4 channel as per section 3.6.
+ * \param[out] bursts Caller-allocated buffer for symbols of 8 bursts,
+ * 8 * 2 * 58 == 928 bits total.
+ * \param[in] data Data to be encoded (72 unpacked bits).
+ * \returns 0 in case of success; negative on error */
+int gsm0503_tch_fr24_encode(ubit_t *bursts, const ubit_t *data)
+{
+ ubit_t iB[8 * 114], cB[4 * 114];
+ const ubit_t h = 0;
+
+ /* 3.6.{1-3} Block code and Convolutional encoder */
+ osmo_conv_encode(&gsm0503_tch_f24, &data[0], &cB[0]);
+
+ /* 3.6.4 Interleaving: as specified for the TCH/FS in subclause 3.1.3 */
+ gsm0503_tch_fr_interleave(&cB[0], &iB[0]);
+
+ /* 3.6.5 Mapping on a burst: as specified for TCH/FS in subclause 3.1.4 */
+ for (unsigned int i = 0; i < 8; i++)
+ gsm0503_tch_burst_map(&iB[i * 114], &bursts[i * 116], &h, i >> 2);
+
+ return 0;
+}
+
+/*! Perform channel decoding of a TCH/F2.4 channel as per section 3.6.
+ * \param[out] data Caller-allocated buffer for decoded data (72 unpacked bits).
+ * \param[in] bursts Buffer containing the symbols of 8 bursts,
+ * 8 * 2 * 58 == 928 bits total.
+ * \param[out] n_errors Number of detected bit errors.
+ * \param[out] n_bits_total Total number of bits.
+ * \returns Number of unpacked bits used in the output buffer; negative on error. */
+int gsm0503_tch_fr24_decode(ubit_t *data, const sbit_t *bursts,
+ int *n_errors, int *n_bits_total)
+{
+ sbit_t iB[8 * 114], cB[4 * 114];
+
+ /* 3.6.5 Mapping on a burst: as specified for TCH/FS in subclause 3.1.4 */
+ for (unsigned int i = 0; i < 8; i++)
+ gsm0503_tch_burst_unmap(&iB[i * 114], &bursts[i * 116], NULL, i >> 2);
+
+ /* 3.6.4 Interleaving: as specified for the TCH/FS in subclause 3.1.3 */
+ gsm0503_tch_fr_deinterleave(&cB[0], &iB[0]);
+
+ /* 3.6.{1-3} Block code and Convolutional encoder */
+ osmo_conv_decode_ber(&gsm0503_tch_f24, &cB[0], &data[0], n_errors, n_bits_total);
+
+ return 72;
+}
+
/*! Perform channel encoding of a TCH/H2.4 channel as per section 3.7.
* \param[out] bursts Caller-allocated buffer for symbols of 22 bursts,
* 22 * 2 * 58 == 2552 bits total.
diff --git a/src/coding/libosmocoding.map b/src/coding/libosmocoding.map
index b1087e3..0444690 100644
--- a/src/coding/libosmocoding.map
+++ b/src/coding/libosmocoding.map
@@ -135,6 +135,8 @@
gsm0503_tch_fr48_decode;
gsm0503_tch_hr48_encode;
gsm0503_tch_hr48_decode;
+gsm0503_tch_fr24_encode;
+gsm0503_tch_fr24_decode;
gsm0503_tch_hr24_encode;
gsm0503_tch_hr24_decode;
gsm0503_tch_fr144_encode;
diff --git a/tests/coding/coding_test.c b/tests/coding/coding_test.c
index 7cef7b3..c9508f7 100644
--- a/tests/coding/coding_test.c
+++ b/tests/coding/coding_test.c
@@ -564,8 +564,14 @@
.half_rate = true,
},
{
+ .name = "TCH/F2.4",
+ .num_bits = 2 * 36,
+ .enc_fn = &gsm0503_tch_fr24_encode,
+ .dec_fn = &gsm0503_tch_fr24_decode,
+ },
+ {
.name = "TCH/H2.4",
- .num_bits = 2 * 72,
+ .num_bits = 4 * 36,
.enc_fn = &gsm0503_tch_hr24_encode,
.dec_fn = &gsm0503_tch_hr24_decode,
.half_rate = true,
diff --git a/tests/coding/coding_test.ok b/tests/coding/coding_test.ok
index c5c145d..1fc2f1d 100644
--- a/tests/coding/coding_test.ok
+++ b/tests/coding/coding_test.ok
@@ -445,6 +445,16 @@
11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111
11111111 11111111 11111111 11111111 11111111 11111111
+test_csd(TCH/F2.4): block #0 (pattern 0x00): n_errors=0 / n_bits_total=456
+00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
+00000000
+test_csd(TCH/F2.4): block #1 (pattern 0xaa): n_errors=0 / n_bits_total=456
+01010101 01010101 01010101 01010101 01010101 01010101 01010101 01010101
+01010101
+test_csd(TCH/F2.4): block #2 (pattern 0xff): n_errors=0 / n_bits_total=456
+11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111
+11111111
+
test_csd(TCH/H2.4): block #0 (pattern 0x00): n_errors=0 / n_bits_total=456
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
@@ -527,6 +537,18 @@
test_csd(TCH/H4.8): FACCH/H (pattern 0x2b): n_errors=0 / n_bits_total=456
2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+test_csd(TCH/F2.4): block #0 (pattern 0x00): n_errors=0 / n_bits_total=456
+00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
+00000000
+test_csd(TCH/F2.4): block #1 (pattern 0xaa): n_errors=138 / n_bits_total=456
+11000010 10010010 10010010 10010010 10010010 10010010 10010101 00011000
+01001010
+test_csd(TCH/F2.4): block #2 (pattern 0xff): n_errors=0 / n_bits_total=456
+11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111
+11111111
+test_csd(TCH/F2.4): FACCH/F (pattern 0x2b): n_errors=0 / n_bits_total=456
+2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+
test_csd(TCH/H2.4): block #0 (pattern 0x00): n_errors=38 / n_bits_total=456
00000000 00000000 00000101 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
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