tbf: Add adaptive DL CS adjustment

To cope with transmission failures due to bad radio conditions, a
different coding scheme with more redundance can be used.

This commit adds an implemenation that is based on the Ack/Nack
ratio per PACKET DOWNLINK ACK/NACK message received from the MS.

Basically the CS level is decreased, if the block error rate goes
above cs_adj_upper_limit (default 33%), and it is increased, if the
rate drops below cs_adj_lower_limit (default 10%). Only blocks that
have been encoded with the current CS are taken into account.

Note that this approach doesn't measure the MS->BTS conditions and
that the measurement values reported by the MS are not taken into
account.

Ticket: #1739
Sponsored-by: On-Waves ehf

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gprs_ms.h b/src/gprs_ms.h
index 01858366..27c4be40 100644
--- a/src/gprs_ms.h
+++ b/src/gprs_ms.h
@@ -86,6 +86,8 @@ public:
 
 	void detach_tbf(gprs_rlcmac_tbf *tbf);
 
+	void update_error_rate(gprs_rlcmac_tbf *tbf, int percent);
+
 	bool is_idle() const {return !m_ul_tbf && !m_dl_tbf && !m_ref;}
 
 	void* operator new(size_t num);