Update MCS selection for retransmission
In 3GPP TS 44.060 the selection of MCS for retransmissions is defined as
separate tables (8.1.1.1 and 8.1.1.2) depending on the value of
resegmentation bit (which is opposite to the way EGPRS_ARQ are defined
in the source code). Let's follow the same idea and explicitly check for
resegmentation bit value and use separate tables. This also makes it
easier to add proper support for special cases (MCS-6-9 and MCS-5-7) and
padding in future independently for different ARQ types. The code is
also moved to c to avoid unnecessary conversions to and from cpp class.
Change-Id: Ia73baeefee7a58834f0fc50e3b8bf8d5e3eb7815
diff --git a/src/coding_scheme.c b/src/coding_scheme.c
index a4ae882..eaa4953 100644
--- a/src/coding_scheme.c
+++ b/src/coding_scheme.c
@@ -127,3 +127,39 @@
const char *mode_name(enum mcs_kind val) {
return get_value_string(mode_names, val);
}
+
+/* FIXME: take into account padding and special cases of commanded MCS (MCS-6-9 and MCS-5-7) */
+enum CodingScheme get_retx_mcs(enum CodingScheme initial_mcs, enum CodingScheme commanded_mcs, bool resegment_bit)
+{
+ OSMO_ASSERT(mcs_is_edge(initial_mcs));
+ OSMO_ASSERT(mcs_is_edge(commanded_mcs));
+ OSMO_ASSERT(NUM_SCHEMES - MCS1 == 9);
+
+ if (resegment_bit) { /* 3GPP TS 44.060 Table 8.1.1.1, reflected over antidiagonal */
+ enum CodingScheme egprs_reseg[NUM_SCHEMES - MCS1][NUM_SCHEMES - MCS1] = {
+ { MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1 },
+ { MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2 },
+ { MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3 },
+ { MCS1, MCS1, MCS1, MCS4, MCS4, MCS4, MCS4, MCS4, MCS4 },
+ { MCS2, MCS2, MCS2, MCS2, MCS5, MCS5, MCS7, MCS7, MCS7 },
+ { MCS3, MCS3, MCS3, MCS3, MCS3, MCS6, MCS6, MCS6, MCS9 },
+ { MCS2, MCS2, MCS2, MCS2, MCS5, MCS5, MCS7, MCS7, MCS7 },
+ { MCS3, MCS3, MCS3, MCS3, MCS3, MCS6, MCS6, MCS8, MCS8 },
+ { MCS3, MCS3, MCS3, MCS3, MCS3, MCS6, MCS6, MCS6, MCS9 },
+ };
+ return egprs_reseg[mcs_chan_code(initial_mcs)][mcs_chan_code(commanded_mcs)];
+ } else { /* 3GPP TS 44.060 Table 8.1.1.2, reflected over antidiagonal */
+ enum CodingScheme egprs_no_reseg[NUM_SCHEMES - MCS1][NUM_SCHEMES - MCS1] = {
+ { MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1, MCS1 },
+ { MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2, MCS2 },
+ { MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3, MCS3 },
+ { MCS4, MCS4, MCS4, MCS4, MCS4, MCS4, MCS4, MCS4, MCS4 },
+ { MCS5, MCS5, MCS5, MCS5, MCS5, MCS5, MCS7, MCS7, MCS7 },
+ { MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS9 },
+ { MCS5, MCS5, MCS5, MCS5, MCS5, MCS5, MCS7, MCS7, MCS7 },
+ { MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS8, MCS8 },
+ { MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS6, MCS9 },
+ };
+ return egprs_no_reseg[mcs_chan_code(initial_mcs)][mcs_chan_code(commanded_mcs)];
+ }
+}