bssgp: Use measured leak rate for flow control (EXPERIMENTAL)

THIS IS EXPERIMENTAL, DO NOT USE IN PRODUCTION

The leak rate sent to the SGSN does not reflect the current CS level,
lost frames, and control message overhead.

Use the ratio between sent blocks and successfully received bytes to
derive the net leak rate.

TODO:
- The values are not stable, possibly resulting from interference
  with the sampling rate or from the interval between send and
  receive if they fall into different sampling intervals.
- Perhaps the rate can be computed from sent data bytes / sent data
  frames or from the average packet size and the global nack rate.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp
index dedea26..0fc252a 100644
--- a/src/gprs_rlcmac_sched.cpp
+++ b/src/gprs_rlcmac_sched.cpp
@@ -321,6 +321,10 @@ int gprs_rlcmac_rcv_rts_block(struct gprs_rlcmac_bts *bts,
 	if (!msg)
 		msg = sched_select_downlink(bts, trx, ts, fn, block_nr, pdch);
 
+	/* Used to calculate the net leak rate, must not include dummy messages */
+	if (msg)
+		gprs_bssgp_update_frames_sent();
+
 	/* Prio 3: send dummy contol message */
 	if (!msg)
 		msg = sched_dummy();