l1: Use the FN of all data_ind/ra_ind DSP messages

Currently all of these messages are discarded if they are assumend to
be caused by noise. But even in these cases, the FN and TN values
which are added by the DSP are valid. So these can be used to update
the current_frame value.

The osmo-bts sets the fBFILevel of a physical channel to -200dB if it
is used for PDTCH or PACCH which is the case for all PDCH. This way
a data_ind or ra_ind message is already send at least once per block
period (4 frames) per PDCH. These messages are passed to either
handle_ph_data_ind or handle_ph_ra_ind even if they contain garbage
data.

The ra_ind messages are sometimes sent a few frames earlier than
data_ind messages using the same frame.

This commit adds calls to update the current_frame value based on all
of these messages before they are discarded. The FN taken from ra_ind
are passed with an increased max_delay (5) to compensate for early
ra_ind messages.

Sponsored-by: On-Waves ehf

5 files changed, 25 insertions, 9 deletions

diff --git a/src/bts.cpp b/src/bts.cpp
index 456990a0..cfb43857 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -153,7 +153,7 @@ void BTS::set_current_frame_number(int fn)
 	m_pollController.expireTimedout(m_cur_fn, max_delay);
 }
 
-void BTS::set_current_block_frame_number(int fn)
+void BTS::set_current_block_frame_number(int fn, unsigned max_delay)
 {
 	int delay = 0;
 	const int late_block_delay_thresh = 13;
@@ -184,7 +184,7 @@ void BTS::set_current_block_frame_number(int fn)
 		current_frame_number() == 0)
 		m_cur_fn = fn;
 
-	m_pollController.expireTimedout(fn, 0);
+	m_pollController.expireTimedout(fn, max_delay);
 }
 
 int BTS::add_paging(uint8_t chan_needed, uint8_t *identity_lv)
@@ -1120,8 +1120,6 @@ int gprs_rlcmac_pdch::rcv_block(uint8_t *data, uint8_t len, uint32_t fn,
 	bitvec *block;
 	int rc = 0;
 
-	bts()->set_current_block_frame_number(fn);
-
 	switch (payload) {
 	case GPRS_RLCMAC_DATA_BLOCK:
 		rc = rcv_data_block_acknowledged(data, len, meas);
diff --git a/src/bts.h b/src/bts.h
index ac851816..eee62a71 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -245,7 +245,7 @@ public:
 
 	/** TODO: change the number to unsigned */
 	void set_current_frame_number(int frame_number);
-	void set_current_block_frame_number(int frame_number);
+	void set_current_block_frame_number(int frame_number, unsigned max_delay);
 	int current_frame_number() const;
 
 	/** add paging to paging queue(s) */
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 9d7d9c48..9d7dbee5 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -180,6 +180,17 @@ void pcu_l1if_tx_pch(bitvec * block, int plen, const char *imsi)
 	pcu_tx_data_req(0, 0, PCU_IF_SAPI_PCH, 0, 0, 0, data, 23+3);
 }
 
+extern "C" void pcu_rx_block_time(uint16_t arfcn, uint32_t fn, uint8_t ts_no)
+{
+	BTS::main_bts()->set_current_block_frame_number(fn, 0);
+}
+
+extern "C" void pcu_rx_ra_time(uint16_t arfcn, uint32_t fn, uint8_t ts_no)
+{
+	/* access bursts may arrive some bursts earlier */
+	BTS::main_bts()->set_current_block_frame_number(fn, 5);
+}
+
 extern "C" int pcu_rx_data_ind_pdtch(uint8_t trx_no, uint8_t ts_no, uint8_t *data,
 	uint8_t len, uint32_t fn, struct pcu_l1_meas *meas)
 {
diff --git a/src/pcu_l1_if.h b/src/pcu_l1_if.h
index 59b9cba2..865c833d 100644
--- a/src/pcu_l1_if.h
+++ b/src/pcu_l1_if.h
@@ -122,15 +122,18 @@ int pcu_sock_send(struct msgb *msg);
 #endif
 
 #ifdef __cplusplus
-extern "C"
+extern "C" {
 #endif
 int pcu_rx_rts_req_pdtch(uint8_t trx, uint8_t ts, uint16_t arfcn,
 	uint32_t fn, uint8_t block_nr);
 
-#ifdef __cplusplus
-extern "C"
-#endif
 int pcu_rx_data_ind_pdtch(uint8_t trx, uint8_t ts, uint8_t *data,
 	uint8_t len, uint32_t fn, struct pcu_l1_meas *meas);
 
+void pcu_rx_block_time(uint16_t arfcn, uint32_t fn, uint8_t ts_no);
+void pcu_rx_ra_time(uint16_t arfcn, uint32_t fn, uint8_t ts_no);
+
+#ifdef __cplusplus
+}
+#endif
 #endif // PCU_L1_IF_H
diff --git a/src/sysmo_l1_if.c b/src/sysmo_l1_if.c
index fc4b59b1..85727861 100644
--- a/src/sysmo_l1_if.c
+++ b/src/sysmo_l1_if.c
@@ -190,6 +190,8 @@ static int handle_ph_data_ind(struct femtol1_hdl *fl1h,
 		osmo_hexdump(data_ind->msgUnitParam.u8Buffer,
 			     data_ind->msgUnitParam.u8Size));
 
+	pcu_rx_block_time(data_ind->u16Arfcn, data_ind->u32Fn, data_ind->u8Tn);
+
 	/*
 	 * TODO: Add proper bad frame handling here. This could be used
 	 * to switch the used CS. Avoid a crash with the PCU right now
@@ -237,6 +239,8 @@ static int handle_ph_ra_ind(struct femtol1_hdl *fl1h, GsmL1_PhRaInd_t *ra_ind)
 {
 	uint8_t acc_delay;
 
+	pcu_rx_ra_time(ra_ind->u16Arfcn, ra_ind->u32Fn, ra_ind->u8Tn);
+
 	if (ra_ind->measParam.fLinkQuality < MIN_QUAL_RACH)
 		return 0;