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Harald Welte gerrit-no-reply at lists.osmocom.orgHarald Welte has submitted this change and it was merged. Change subject: common/l1sap.c: limit the minimal ToA for RACH bursts ...................................................................... common/l1sap.c: limit the minimal ToA for RACH bursts In general, RACH bursts should not arrive with negative offset. Let's limit early signal arrival up to 2 symbols, otherwise it is most likely noise, interference or a ghost. TTCN-3 test case: Icccc88545ed3aabd6da28a40599a8a77d1de477d Change-Id: I662294fe3136cf7a259be13816a3e63f7db9a948 --- M src/common/l1sap.c 1 file changed, 12 insertions(+), 4 deletions(-) Approvals: Harald Welte: Looks good to me, approved Jenkins Builder: Verified diff --git a/src/common/l1sap.c b/src/common/l1sap.c index ce68599..8380175 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -1159,9 +1159,13 @@ return 0; } +#define RACH_MIN_TOA256 -2 * 256 + static bool rach_pass_filter(struct ph_rach_ind_param *rach_ind, struct gsm_bts_role_bts *btsb) { + int16_t toa256 = rach_ind->acc_delay_256bits; + /* Check for RACH exceeding BER threshold (ghost RACH) */ if (rach_ind->ber10k > btsb->max_ber10k_rach) { LOGPFN(DL1C, LOGL_INFO, rach_ind->fn, "Ignoring RACH request: " @@ -1170,11 +1174,15 @@ return false; } - /* Make sure that ToA (Timing of Arrival) is acceptable */ - if (rach_ind->acc_delay > btsb->max_ta) { + /** + * Make sure that ToA (Timing of Arrival) is acceptable. + * We allow early arrival up to 2 symbols, and delay + * according to maximal allowed Timing Advance value. + */ + if (toa256 < RACH_MIN_TOA256 || toa256 > btsb->max_ta * 256) { LOGPFN(DL1C, LOGL_INFO, rach_ind->fn, "Ignoring RACH request: " - "ToA(%u) exceeds the maximal allowed TA(%u) value\n", - rach_ind->acc_delay, btsb->max_ta); + "ToA(%d) exceeds the allowed range (%d..%d)\n", + toa256, RACH_MIN_TOA256, btsb->max_ta * 256); return false; } -- To view, visit https://gerrit.osmocom.org/7089 To unsubscribe, visit https://gerrit.osmocom.org/settings Gerrit-MessageType: merged Gerrit-Change-Id: I662294fe3136cf7a259be13816a3e63f7db9a948 Gerrit-PatchSet: 3 Gerrit-Project: osmo-bts Gerrit-Branch: master Gerrit-Owner: Vadim Yanitskiy <axilirator at gmail.com> Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org> Gerrit-Reviewer: Jenkins Builder