diff options
| author | Harald Welte <laforge@gnumonks.org> | 2016-06-27 18:56:01 +0200 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2018-02-27 17:27:46 +0100 |
| commit | b3a2a3e24f44adcc6660d33cc9684a8f24271e2e (patch) | |
| tree | cd0993648158ad2c050553a6e99dc72d21e4a95a /src/common/l1sap.c | |
| parent | c2b4c668f3510b7b0baace749c5a310959010e90 (diff) | |
RACH decoding: Use BER threshold for RACH ghost detection
When decoding RACH bursts, we should use a BER threshold in order to
help distinguish 'ghost' RACH bursts from real RACH bursts.
The theoretical ideal threshold according to some papers is 7 out of 41
bits qhich aquals to Eb/N0 of 0 dB = 0.1707 (17.07%)
We add a new 'ber10k' parameter to the RACH indication l1sap primitive
(needs separate change for libosmocore), and then fill this value from
osmo-bts-{sysmo,lc15,trx,octphy}. The common part above L1SAP then
applies the threshold, which can be changed from vty using the
"max-ber10k-rach <0-10000>"
command available at the BTS node. The unit is BER in 1/10000, i.e. a
value of 100 equals 1% bit error rate.
Change-Id: Ic41c11f6312a36baa2738547e8dcec80829457f8
Diffstat (limited to 'src/common/l1sap.c')
| -rw-r--r-- | src/common/l1sap.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/common/l1sap.c b/src/common/l1sap.c index 90f045a2..50bd612d 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -1203,7 +1203,12 @@ static int l1sap_ph_rach_ind(struct gsm_bts_trx *trx, if (rach_ind->rssi >= btsb->load.rach.busy_thresh) btsb->load.rach.busy++; - /* FIXME: RACH filtering due to BER limit */ + /* check for RACH exceeding BER threshold (ghost RACH) */ + if (rach_ind->ber10k > btsb->max_ber10k_rach) { + DEBUGPFN(DL1C, rach_ind->fn, "ignoring RACH request: %u > %u (max BER)\n", + rach_ind->ber10k, btsb->max_ber10k_rach); + return 0; + } /* increment number of RACH slots with valid non-handover RACH burst */ btsb->load.rach.access++; |