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Rewrite Packet Uplink IA Rest Octets for SBA 

Use bitvec_set_*() directly without external write pointer tracking to
simplify the code. This is part of IA Rest Octets (3GPP TS 44.018
§10.5.2.16) which is the last part of the message so it should not
interfere with the rest of encoding functions.

The difference in the expected test output is due to proper handling of
TAI which should not be transmitted for SBA according to the Note in
Table 10.5.2.16.1 in 3GPP TS 44.018.

The change was manually tested against real mobile phone using options
'gprs mode gprs' in osmo-bsc.cfg and 'two-phase-access' in osmo-pcu.cfg
to make sure appropriate code path is actually triggered.

That's partially based on reverted commit 93d947f5e8.

Change-Id: I97d53c27c1ca9e032d431b3aa7f915027d63ddc0
Related: OS#3014
This commit is contained in:
Max 2019-02-19 18:41:22 +01:00
parent 0367ddd62b
commit 3eb47363ad
3 changed files with 24 additions and 17 deletions
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37
src/encoding.cpp
View File

@ -233,25 +233,31 @@ static int write_ia_rest_downlink(const gprs_rlcmac_dl_tbf *tbf, bitvec * dest,
return rc;
}
static int write_ia_rest_uplink_sba(bitvec *dest, uint32_t fn, uint8_t alpha, uint8_t gamma, int8_t ta_idx,
unsigned& wp)
/* 3GPP TS 44.018 Table 10.5.2.16.1 < Packet Uplink Assignment > -- Single Block Allocation */
static int write_ia_rest_uplink_sba(bitvec *dest, uint32_t fn, uint8_t alpha, uint8_t gamma)
{
int rc = 0;
bitvec_write_field(dest, &wp, 0, 1); // Block Allocation: Single Block Allocation
SET_0(dest); /* Single Block Allocation */
rc = write_alpha_gamma(dest, alpha, gamma);
CHECK(rc);
if (alpha) {
bitvec_write_field(dest, &wp, 0x1, 1); // ALPHA = present
bitvec_write_field(dest, &wp, alpha, 4);
} else
bitvec_write_field(dest, &wp, 0x0, 1); // ALPHA = not present
/* A 'Timing Advance index' shall not be allocated at a Single Block allocation.
A 'TBF Starting Time' shall be allocated at a Single Block allocation. */
SET_0(dest);
SET_1(dest);
bitvec_write_field(dest, &wp, gamma, 5); // GAMMA power control parameter
write_tai(dest, wp, ta_idx);
bitvec_write_field(dest, &wp, 1, 1); // TBF_STARTING_TIME_FLAG
bitvec_write_field(dest, &wp, (fn / (26 * 51)) % 32, 5); // T1'
bitvec_write_field(dest, &wp, fn % 51, 6); // T3
bitvec_write_field(dest, &wp, fn % 26, 5); // T2
rc = write_tbf_start_time(dest, fn);
CHECK(rc);
/* No P0 nor PR_MODE */
SET_L(dest);
/* No Additions for R99 */
SET_L(dest);
/* No Additions for Rel-6 */
SET_L(dest);
return rc;
}
@ -523,7 +529,8 @@ int Encoding::write_immediate_assignment(
dest->cur_bit = wp;
rc = write_ia_rest_uplink_mba(as_ul_tbf(tbf), dest, usf, alpha, gamma);
} else {
rc = write_ia_rest_uplink_sba(dest, fn, alpha, gamma, ta_idx, wp);
dest->cur_bit = wp;
rc = write_ia_rest_uplink_sba(dest, fn, alpha, gamma);
}
}

2
tests/types/TypesTest.cpp
View File

@ -514,7 +514,7 @@ void test_immediate_assign_ul0s()
0x23, /* TA */
0x00, /* 0-length §10.5.2.21 Mobile Allocation */
/* ETSI TS 44.018 §10.5.2.16 IA Rest Octets */
0xc5, 0xd1, 0x08, 0x0b, 0x5b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
0xc5, 0xd0, 0x80, 0xb5, 0xab, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
check_imm_ass(NULL, false, GSM_L1_BURST_TYPE_ACCESS_0, res, sizeof(res), "ia_rest_uplink(SBA)");
}

2
tests/types/TypesTest.ok
View File

@ -11,7 +11,7 @@ show_rbb: IIRRIIIR
[11] UL Immediate Assignment <ia_rest_uplink(MBA)>:
06 3f 10 0d 23 6d 0d 03 18 23 00 c8 02 1b a0 2b 2b 2b 2b 2b 2b 2b 2b
[11] UL Immediate Assignment <ia_rest_uplink(SBA)>:
06 3f 10 0d 23 6d 0d 03 18 23 00 c5 d1 08 0b 5b 2b 2b 2b 2b 2b 2b 2b
06 3f 10 0d 23 6d 0d 03 18 23 00 c5 d0 80 b5 ab 2b 2b 2b 2b 2b 2b 2b
[11] UL Immediate Assignment <ia_rest_egprs_uplink(MBA)>:
06 3f 10 0d 23 6d 7f 03 18 23 00 46 97 40 0b 58 2b 2b 2b 2b 2b 2b 2b
[11] UL Immediate Assignment <ia_rest_egprs_uplink(SBA)>: