Fixed contention resolution issue

In order to do downlink assignment during uplink TBF, the content
resolution must be completed. It is completed when the first Packet
Uplink Ack/Nack message is transmitted to the mobile.

3 files changed, 24 insertions, 11 deletions

diff --git a/src/gprs_rlcmac.h b/src/gprs_rlcmac.h
index 1e6bc0d2..ae188f13 100644
--- a/src/gprs_rlcmac.h
+++ b/src/gprs_rlcmac.h
@@ -134,6 +134,7 @@ struct gprs_rlcmac_tbf {
 	uint8_t tfi;
 	uint32_t tlli;
 	uint8_t tlli_valid;
+	uint8_t contention_resolution_done; /* set after done */
 	uint8_t trx;
 	uint16_t arfcn;
 	uint8_t tsc;
diff --git a/src/gprs_rlcmac_data.cpp b/src/gprs_rlcmac_data.cpp
index 9b3a0953..76cc0332 100644
--- a/src/gprs_rlcmac_data.cpp
+++ b/src/gprs_rlcmac_data.cpp
@@ -218,7 +218,7 @@ uplink_request:
 				break;
 			}
 			ul_tbf->tlli = tbf->tlli;
-			ul_tbf->tlli_valid = 1; /* no content resolution */
+			ul_tbf->tlli_valid = 1; /* no contention resolution */
 			ul_tbf->ta = tbf->ta; /* use current TA */
 			tbf_new_state(ul_tbf, GPRS_RLCMAC_FLOW);
 			tbf_timer_start(ul_tbf, 3169, bts->t3169, 0);
@@ -550,6 +550,10 @@ struct msgb *gprs_rlcmac_send_uplink_ack(struct gprs_rlcmac_tbf *tbf,
 	bitvec_free(ack_vec);
 	free(mac_control_block);
 
+	/* now we must set this flag, so we are allowed to assign downlink
+	 * TBF on PACCH. it is only allowed when TLLI is aknowledged. */
+	tbf->contention_resolution_done = 1;
+
 	if (final) {
 		tbf->poll_state = GPRS_RLCMAC_POLL_SCHED;
 		tbf->poll_fn = (fn + 13) % 2715648;
@@ -1143,6 +1147,8 @@ tx_block:
 				"sheduled in this TS %d, waiting for "
 				"TS %d\n", ts, tbf->control_ts);
 		else  {
+			LOGP(DRLCMAC, LOGL_DEBUG, "Polling sheduled in this "
+				"TS %d\n", ts);
 			/* start timer whenever we send the final block */
 			if (rh->fbi == 1)
 				tbf_timer_start(tbf, 3191, bts->t3191, 0);
@@ -1308,9 +1314,17 @@ struct msgb *gprs_rlcmac_send_packet_downlink_assignment(
 #endif
 
 	/* on uplink TBF we get the downlink TBF to be assigned. */
-	if (tbf->direction == GPRS_RLCMAC_UL_TBF)
+	if (tbf->direction == GPRS_RLCMAC_UL_TBF) {
+		/* be sure to check first, if contention resolution is done,
+		 * otherwise we cannot send the assignment yet */
+		if (!tbf->contention_resolution_done) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "Cannot assign DL TBF now, "
+				"because contention resolution is not "
+				"finished.\n");
+			return NULL;
+		}
 		new_tbf = tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_DL_TBF);
-	else
+	} else
 		new_tbf = tbf;
 	if (!new_tbf) {
 		LOGP(DRLCMACDL, LOGL_ERROR, "We have a schedule for downlink "
diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp
index f88b09b5..cd995166 100644
--- a/src/gprs_rlcmac_sched.cpp
+++ b/src/gprs_rlcmac_sched.cpp
@@ -69,12 +69,12 @@ int gprs_rlcmac_rcv_rts_block(uint8_t trx, uint8_t ts, uint16_t arfcn,
 		if (tbf->poll_state == GPRS_RLCMAC_POLL_SCHED
 		 && tbf->poll_fn == poll_fn)
 			poll_tbf = tbf;
+		if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_SEND_ACK)
+			ul_ack_tbf = tbf;
 		if (tbf->dl_ass_state == GPRS_RLCMAC_DL_ASS_SEND_ASS)
 			dl_ass_tbf = tbf;
 		if (tbf->ul_ass_state == GPRS_RLCMAC_UL_ASS_SEND_ASS)
 			ul_ass_tbf = tbf;
-		if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_SEND_ACK)
-			ul_ack_tbf = tbf;
 	}
 	llist_for_each_entry(tbf, &gprs_rlcmac_dl_tbfs, list) {
 		/* this trx, this ts */
@@ -88,8 +88,6 @@ int gprs_rlcmac_rcv_rts_block(uint8_t trx, uint8_t ts, uint16_t arfcn,
 			dl_ass_tbf = tbf;
 		if (tbf->ul_ass_state == GPRS_RLCMAC_UL_ASS_SEND_ASS)
 			ul_ass_tbf = tbf;
-		if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_SEND_ACK)
-			ul_ack_tbf = tbf;
 	}
 
 	/* check uplink ressource for polling */
@@ -134,14 +132,14 @@ int gprs_rlcmac_rcv_rts_block(uint8_t trx, uint8_t ts, uint16_t arfcn,
 	if (dl_ass_tbf) {
 		tbf = dl_ass_tbf;
 		msg = gprs_rlcmac_send_packet_downlink_assignment(tbf, fn);
-	} else
+	}
 	/* schedule PACKET UPLINK ASSIGNMENT */
-	if (ul_ass_tbf) {
+	if (!msg && ul_ass_tbf) {
 		tbf = ul_ass_tbf;
 		msg = gprs_rlcmac_send_packet_uplink_assignment(tbf, fn);
-	} else
+	}
 	/* schedule PACKET UPLINK ACK */
-	if (ul_ack_tbf) {
+	if (!msg && ul_ack_tbf) {
 		tbf = ul_ack_tbf;
 		msg = gprs_rlcmac_send_uplink_ack(tbf, fn);
 	}