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tbf_ul: Fix UL ACK not sent to MS if intermediate UL block is lost 

In normal conditions ACKing of UL blocks is only sent every
SEND_ACK_AFTER_FRAMES (20) frames. Which means if CV=0 is received (and
hence no more packets are received) less than 20 frames before a lost,
the PCU won't ask for a retransmission and wait there until some timer
destroys the TBF.

This issue is shown by TTCN3 test PCU_Tests.ttcn
TC_ul_intermediate_retrans.

Unit tests triggering this condition are adapted. Some similar tests are
not triggering it because BSN/CV relation being used is totally wrong
(like CV=0 being sent on a BSN with previous value than others).

Change-Id: I9b4ef7b7277efa645bdb5becf2e9f6b32c99a9b1
This commit is contained in:
Pau Espin 2020-05-15 16:57:48 +02:00 committed by pespin
parent 5bb87b83d1
commit c33a024d4a
4 changed files with 25 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/tbf_ul.cpp
View File

@ -188,6 +188,9 @@ int gprs_rlcmac_ul_tbf::rcv_data_block_acknowledged(
const struct gprs_rlc_data_info *rlc,
uint8_t *data, struct pcu_l1_meas *meas)
{
const struct gprs_rlc_data_block_info *rdbi;
struct gprs_rlc_data *block;
int8_t rssi = meas->have_rssi ? meas->rssi : 0;
const uint16_t ws = m_window.ws();
@ -218,10 +221,8 @@ int gprs_rlcmac_ul_tbf::rcv_data_block_acknowledged(
for (block_idx = 0; block_idx < rlc->num_data_blocks; block_idx++) {
int num_chunks;
uint8_t *rlc_data;
const struct gprs_rlc_data_block_info *rdbi =
&rlc->block_info[block_idx];
rdbi = &rlc->block_info[block_idx];
bool need_rlc_data = false;
struct gprs_rlc_data *block;
LOGPTBFUL(this, LOGL_DEBUG,
"Got %s RLC data block: CV=%d, BSN=%d, SPB=%d, PI=%d, E=%d, TI=%d, bitoffs=%d\n",
@ -330,14 +331,13 @@ int gprs_rlcmac_ul_tbf::rcv_data_block_acknowledged(
assemble_forward_llc(m_rlc.block(index));
}
/* Check CV of last frame in buffer */
/* Last frame in buffer: */
block = m_rlc.block(m_window.mod_sns(m_window.v_r() - 1));
rdbi = &block->block_info;
/* Check if we already received all data TBF had to send: */
if (this->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
&& this->m_window.v_q() == this->m_window.v_r()) { /* if complete */
struct gprs_rlc_data *block =
m_rlc.block(m_window.mod_sns(m_window.v_r() - 1));
const struct gprs_rlc_data_block_info *rdbi =
&block->block_info;
LOGPTBFUL(this, LOGL_DEBUG,
"No gaps in received block, last block: BSN=%d CV=%d\n",
rdbi->bsn, rdbi->cv);
@ -351,13 +351,13 @@ int gprs_rlcmac_ul_tbf::rcv_data_block_acknowledged(
/* If TLLI is included or if we received half of the window, we send
* an ack/nack */
maybe_schedule_uplink_acknack(rlc);
maybe_schedule_uplink_acknack(rlc, rdbi->cv == 0);
return 0;
}
void gprs_rlcmac_ul_tbf::maybe_schedule_uplink_acknack(
const gprs_rlc_data_info *rlc)
const gprs_rlc_data_info *rlc, bool countdown_finished)
{
bool require_ack = false;
bool have_ti = rlc->block_info[0].ti ||
@ -373,10 +373,14 @@ void gprs_rlcmac_ul_tbf::maybe_schedule_uplink_acknack(
LOGPTBFUL(this, LOGL_DEBUG,
"Scheduling Ack/Nack, because TLLI is included.\n");
}
if (state_is(GPRS_RLCMAC_FINISHED)) {
if (countdown_finished) {
require_ack = true;
LOGPTBFUL(this, LOGL_DEBUG,
"Scheduling final Ack/Nack, because all data was received and last block has CV==0.\n");
if (state_is(GPRS_RLCMAC_FLOW))
LOGPTBFUL(this, LOGL_DEBUG,
"Scheduling Ack/Nack, because some data is missing and last block has CV==0.\n");
else if (state_is(GPRS_RLCMAC_FINISHED))
LOGPTBFUL(this, LOGL_DEBUG,
"Scheduling final Ack/Nack, because all data was received and last block has CV==0.\n");
}
if ((m_rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
require_ack = true;

4
src/tbf_ul.h
View File

@ -21,6 +21,8 @@
#ifdef __cplusplus
#include <stdbool.h>
#include "tbf.h"
/*
* TBF instance
@ -97,7 +99,7 @@ struct gprs_rlcmac_ul_tbf : public gprs_rlcmac_tbf {
struct rate_ctr_group *m_ul_egprs_ctrs;
protected:
void maybe_schedule_uplink_acknack(const gprs_rlc_data_info *rlc);
void maybe_schedule_uplink_acknack(const gprs_rlc_data_info *rlc, bool countdown_finished);
/* Please note that all variables below will be reset when changing
* from WAIT RELEASE back to FLOW state (re-use of TBF).

1
tests/tbf/TbfTest.cpp
View File

@ -1459,6 +1459,7 @@ static gprs_rlcmac_ul_tbf *establish_ul_tbf_two_phase_puan_URBB_with_length(BTS
pdch = &the_bts->bts_data()->trx[trx_no].pdch[ts_no];
pdch->rcv_block(&data[0], sizeof(data), *fn, &meas);
ul_tbf->create_ul_ack(*fn, ts_no);
request_dl_rlc_block(ul_tbf, fn);

3
tests/tbf/TbfTest.err
View File

@ -7193,6 +7193,9 @@ TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) restarting timer T3169 [acked
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) Got MCS-4 RLC data block: CV=0, BSN=64, SPB=0, PI=0, E=1, TI=0, bitoffs=33
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) BSN 64 storing in window (1..192)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) data_length=44, data=80 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 95
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) Scheduling Ack/Nack, because some data is missing and last block has CV==0.
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) changes UL ACK state from GPRS_RLCMAC_UL_ACK_NONE to GPRS_RLCMAC_UL_ACK_SEND_ACK
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) changes UL ACK state from GPRS_RLCMAC_UL_ACK_SEND_ACK to GPRS_RLCMAC_UL_ACK_NONE
Received RTS for PDCH: TRX=0 TS=7 FN=2654279 block_nr=10 scheduling USF=0 for required uplink resource of UL TFI=0
TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=ASSIGN EGPRS) start Packet Downlink Assignment (PACCH)
+++++++++++++++++++++++++ TX : Packet Downlink Assignment +++++++++++++++++++++++++