Change in osmo-bts[master]: Do not transmit dummy RLC/MAC blocks on non-BCCH carriers

[fixeria]

fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/24855 )


Change subject: Do not transmit dummy RLC/MAC blocks on non-BCCH carriers
......................................................................

Do not transmit dummy RLC/MAC blocks on non-BCCH carriers

Transmission of dummy RLC/MAC blocks over the Um-interface can be avoided
on non-BCCH carriers for the purpose of energy saving.  The idea is simple:
if a PDCH timeslot has no Uplink nor Downlink TBFs allocated, then (most
likely) nobody is listening to it.  This is indicated by the PCU using the
least significant bit of a new field 'flags' in PCUIF DATA.req messages.

Change-Id: I2bf5271c4f1eaf5a975129f73091eb51cee50e57
Related: SYS#4919, OS#4772
---
M include/osmo-bts/pcuif_proto.h
M src/common/pcu_sock.c
2 files changed, 9 insertions(+), 0 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/55/24855/1

diff --git a/include/osmo-bts/pcuif_proto.h b/include/osmo-bts/pcuif_proto.h
index 3e6f651..c3605ec 100644
--- a/include/osmo-bts/pcuif_proto.h
+++ b/include/osmo-bts/pcuif_proto.h
@@ -68,6 +68,9 @@
 	char		text[TXT_MAX_LEN]; /* Text to be transmitted to BTS */
 } __attribute__ ((packed));
 
+/* Indicates that the PDU contains a dummy RLC/MAC block */
+#define PCU_IF_DATA_F_DUMMY		(1 << 0)
+
 struct gsm_pcu_if_data {
 	uint8_t		sapi;
 	uint8_t		len;
@@ -81,6 +84,7 @@
 	uint16_t	ber10k;		/* !< \brief BER in units of 0.01% */
 	int16_t		ta_offs_qbits;	/* !< \brief Burst TA Offset in quarter bits */
 	int16_t		lqual_cb;	/* !< \brief Link quality in centiBel */
+	uint8_t		flags;		/* !< \brief See See PCU_IF_DATA_F_* above */
 } __attribute__ ((packed));
 
 /* data confirmation with direct tlli (instead of raw mac block with tlli) */
diff --git a/src/common/pcu_sock.c b/src/common/pcu_sock.c
index 41a5ffc..32a572a 100644
--- a/src/common/pcu_sock.c
+++ b/src/common/pcu_sock.c
@@ -690,6 +690,11 @@
 		break;
 	case PCU_IF_SAPI_PDTCH:
 	case PCU_IF_SAPI_PTCCH:
+		/* Energy saving (OS#4772): do not transmit dummy RLC/MAC blocks on non-BCCH
+		 * carriers if the PCU indicates that no TBFs are active at the moment. */
+		if (data_req->flags & PCU_IF_DATA_F_DUMMY)
+			if (data_req->trx_nr > 0)
+				return 0;
 		trx = gsm_bts_trx_num(bts, data_req->trx_nr);
 		if (!trx) {
 			LOGP(DPCU, LOGL_ERROR, "Received PCU data request with "

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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: I2bf5271c4f1eaf5a975129f73091eb51cee50e57
Gerrit-Change-Number: 24855
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de>
Gerrit-MessageType: newchange
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