fixeria has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/27383 )

Change subject: bitvec2freq_list(): fix handling of E-GSM ARFCNs ......................................................................

bitvec2freq_list(): fix handling of E-GSM ARFCNs

According to 3GPP TS 44.018, section 10.5.2.1b.2, only ARFCN values in range 1..124 can be encoded using the 'bit map 0' format. Before this patch, ARFCN values belonging to E-GSM band (0, 975..1023) were ignored in bitvec2freq_list(), and thus not present in the resulting Cell Channel Description IE.

Change-Id: I17739e6845cd84e2a81bc406dd532541f7c52cb6 Related: SYS#5854 --- M src/osmo-bsc/system_information.c M tests/gsm0408/gsm0408_test.ok 2 files changed, 19 insertions(+), 10 deletions(-)

Approvals: Jenkins Builder: Verified pespin: Looks good to me, but someone else must approve fixeria: Looks good to me, approved

diff --git a/src/osmo-bsc/system_information.c b/src/osmo-bsc/system_information.c index 974af3a..e1b369d 100644 --- a/src/osmo-bsc/system_information.c +++ b/src/osmo-bsc/system_information.c @@ -504,20 +504,29 @@ bool pgsm = false; memset(chan_list, 0, 16);

- if (bts->band == GSM_BAND_900 - && bts->c0->arfcn >= 1 && bts->c0->arfcn <= 124) + /* According to 3GPP TS 44.018, section 10.5.2.1b.2, only ARFCN values + * in range 1..124 can be encoded using the 'bit map 0' format. */ + if (bts->band == GSM_BAND_900) pgsm = true; + /* Check presence of E-GSM ARFCN 0 */ + if (pgsm && bitvec_get_bit_pos(bv, 0) == ONE) + pgsm = false; + /* Check presence of E-GSM ARFCNs 975..1023 */ + for (i = 975; pgsm && i <= 1023; i++) { + if (bitvec_get_bit_pos(bv, i) == ONE) + pgsm = false; + } + /* P-GSM-only handsets only support 'bit map 0 format' */ if (!bis && !ter && pgsm) { chan_list[0] = 0;

- for (i = 0; i < bv->data_len*8; i++) { - if (i >= 1 && i <= 124 - && bitvec_get_bit_pos(bv, i)) { - rc = freq_list_bm0_set_arfcn(chan_list, i); - if (rc < 0) - return rc; - } + for (i = 1; i <= 124; i++) { + if (!bitvec_get_bit_pos(bv, i)) + continue; + rc = freq_list_bm0_set_arfcn(chan_list, i); + if (rc < 0) + return rc; } return 0; } diff --git a/tests/gsm0408/gsm0408_test.ok b/tests/gsm0408/gsm0408_test.ok index 26ec931..1a8389d 100644 --- a/tests/gsm0408/gsm0408_test.ok +++ b/tests/gsm0408/gsm0408_test.ok @@ -191,6 +191,6 @@ Testing generation of the Cell Channel Description IE: Case a) only the BCCH carrier: 10 Case b) more carriers from P-GSM band: 1 3 10 64 99 124 -Case c) more carriers from E-GSM band: 1 3 10 64 99 124 +Case c) more carriers from E-GSM band: 0 3 10 64 99 124 975 1001 1023 BTS deallocated OK in test_cell_chan_desc() Done.