edge: Use GprsCodingScheme to adjust the UL RLC block size
Currently the block size is mapped by a switch statement to strip
extra bits that are not used for RLC blocks. That information is
already available via the GprsCodingScheme class.
This commit moves the CS/MCS detection to the rcv_block message and
passes the cs object via rcv_block_gprs, where the length gets
adjusted, to gprs_rlcmac_pdch::rcv_data_block_acknowledged. There the
switch statement is removed.
Note that the TbfTest.err changes due to an additional log message.
Sponsored-by: On-Waves ehf
diff --git a/src/bts.cpp b/src/bts.cpp
index 0e3e8f0..988d5f9 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -733,28 +733,6 @@
struct gprs_rlcmac_ul_tbf *tbf;
struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
- switch (len) {
- case 54:
- /* omitting spare bits */
- len = 53;
- break;
- case 40:
- /* omitting spare bits */
- len = 39;
- break;
- case 34:
- /* omitting spare bits */
- len = 33;
- break;
- case 23:
- break;
- default:
- bts()->decode_error();
- LOGP(DRLCMACUL, LOGL_ERROR, "Dropping data block with invalid"
- "length: %d)\n", len);
- return -EINVAL;
- }
-
/* find TBF inst from given TFI */
tbf = ul_tbf_by_tfi(rh->tfi);
if (!tbf) {
@@ -1166,9 +1144,33 @@
int gprs_rlcmac_pdch::rcv_block(uint8_t *data, uint8_t len, uint32_t fn,
struct pcu_l1_meas *meas)
{
+ GprsCodingScheme cs = GprsCodingScheme::getBySizeUL(len);
+ if (!cs) {
+ bts()->decode_error();
+ LOGP(DRLCMACUL, LOGL_ERROR, "Dropping data block with invalid"
+ "length: %d)\n", len);
+ return -EINVAL;
+ }
+
+ LOGP(DRLCMACUL, LOGL_DEBUG, "Got RLC block, coding scheme: %s, "
+ "length: %d (%d))\n", cs.name(), len, cs.maxBytesUL());
+
+ if (cs.isGprs())
+ return rcv_block_gprs(data, fn, meas, cs);
+
+ bts()->decode_error();
+ LOGP(DRLCMACUL, LOGL_ERROR, "Unsupported coding scheme %s\n",
+ cs.name());
+ return -EINVAL;
+}
+
+int gprs_rlcmac_pdch::rcv_block_gprs(uint8_t *data, uint32_t fn,
+ struct pcu_l1_meas *meas, GprsCodingScheme cs)
+{
unsigned payload = data[0] >> 6;
bitvec *block;
int rc = 0;
+ unsigned len = cs.maxBytesUL();
switch (payload) {
case GPRS_RLCMAC_DATA_BLOCK:
diff --git a/src/bts.h b/src/bts.h
index 8831aca..ecbc0c9 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -33,6 +33,7 @@
#include "sba.h"
#include "tbf.h"
#include "gprs_ms_storage.h"
+#include "gprs_coding_scheme.h"
#endif
#include <stdint.h>
@@ -63,6 +64,8 @@
/* dispatching of messages */
int rcv_block(uint8_t *data, uint8_t len, uint32_t fn,
struct pcu_l1_meas *meas);
+ int rcv_block_gprs(uint8_t *data, uint32_t fn,
+ struct pcu_l1_meas *meas, GprsCodingScheme cs);
gprs_rlcmac_bts *bts_data() const;
BTS *bts() const;
diff --git a/tests/tbf/TbfTest.err b/tests/tbf/TbfTest.err
index 77366b9..1664e85 100644
--- a/tests/tbf/TbfTest.err
+++ b/tests/tbf/TbfTest.err
@@ -1393,6 +1393,7 @@
TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) RX: [PCU <- BTS] RACH qbit-ta=31 ra=0x03, Fn=2654167 (17,25,9)
TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) TX: START Immediate Assignment Uplink (AGCH)
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 03 8b 29 07 00 c8 00 10 0b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
Modifying MS object, UL TLLI: 0x00000000 -> 0xf1223344, not yet confirmed
Decoded premier TLLI=0xf1223344 of UL DATA TFI=0.
@@ -1445,6 +1446,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b 29 07 00 c0 0c 5a 43 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -1476,11 +1478,13 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654283
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654270 block=8 data=4f 28 5e 24 46 68 8f 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1522,6 +1526,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b 29 07 00 c0 0c 5a 43 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -1553,11 +1558,13 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654283
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654270 block=8 data=4f 28 5e 24 46 68 8f 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1598,6 +1605,7 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) Scheduled DL Assignment polling on FN=2654288
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654275 block=9 data=48 08 00 00 0c 72 00 02 08 00 80 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) Packet Control Ack
@@ -1643,6 +1651,7 @@
- Timeout for polling PACKET DOWNLINK ACK.
- Assignment was on PACCH
- No downlink ACK received yet
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -1675,11 +1684,13 @@
TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654348
Scheduling control message at RTS for TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654335 block=11 data=48 28 5e ac ce f1 0f 1d 00 00 88 40 09 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=ASSIGN)
TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=1 received (V(Q)=0 .. V(R)=0)
TBF(TFI=1 TLLI=0xf5667788 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1707,6 +1718,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b 29 07 00 c0 0c 5a 43 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -1738,11 +1750,13 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654283
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654270 block=8 data=4f 28 5e 24 46 68 83 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1792,6 +1806,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b ee 07 00 c0 0c 60 6b 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
Got RACH from TLLI=0xf1223344 while TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=ASSIGN) still exists. Release pending DL TBF
@@ -1822,6 +1837,7 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654340
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654327 block=9 data=4f 28 5e 24 46 68 83 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
@@ -1846,6 +1862,7 @@
Send dowlink assignment on PACCH, because TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) exists
TBF(TFI=1 TLLI=0xf1223344 DIR=DL STATE=NULL) changes state from NULL to ASSIGN
TBF(TFI=1 TLLI=0xf1223344 DIR=DL STATE=ASSIGN) starting timer 0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1864,6 +1881,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b 29 07 00 c0 0c 5a 43 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -1895,11 +1913,13 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654283
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654270 block=8 data=4f 28 5e 24 46 68 83 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -1967,6 +1987,7 @@
TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) RX: [PCU <- BTS] RACH qbit-ta=31 ra=0x03, Fn=2654275 (17,31,13)
TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) TX: START Immediate Assignment Uplink (AGCH)
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 03 8b ed 07 00 c8 00 10 0b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
Detaching TBF from MS object, TLLI = 0xf1223344, TBF = TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=ASSIGN)
Attaching TBF to MS object, TLLI = 0x00000000, TBF = TBF(TFI=0 TLLI=0x00000000 DIR=DL STATE=ASSIGN)
@@ -2001,6 +2022,7 @@
Sending data request: trx=0 ts=0 sapi=2 arfcn=0 fn=0 block=0 data=2d 06 3f 10 0f 00 00 73 8b 29 07 00 c0 0c 5a 43 2b 2b 2b 2b 2b 2b 2b
Searching for first unallocated TFI: TRX=0
Found TFI=0.
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
MS requests UL TBF in packet resource request of single block, so we provide one:
@@ -2032,11 +2054,13 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Scheduled UL Assignment polling on FN=2654283
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654270 block=8 data=4f 28 5e 24 46 68 83 1d 00 00 88 00 08 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) Packet Control Ack
TBF: [DOWNLINK] UPLINK ASSIGNED TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=ASSIGN) changes state from ASSIGN to FLOW
+Got RLC block, coding scheme: CS-1, length: 23 (23))
UL DATA TFI=0 received (V(Q)=0 .. V(R)=0)
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) restarting timer 3169 while old timer 3169 pending
- BSN 0 storing in window (0..63)
@@ -2116,6 +2140,7 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) Scheduled DL Assignment polling on FN=2654288
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654275 block=9 data=48 08 00 00 0c 72 00 02 08 00 80 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW) Packet Control Ack
@@ -2650,6 +2675,7 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=FINISHED) append
TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=FINISHED) append
TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=FINISHED) append
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=FINISHED) Packet Downlink Ack/Nack
@@ -2683,6 +2709,7 @@
TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=WAIT RELEASE) Scheduled DL Assignment polling on FN=2654413
Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=WAIT RELEASE) (TRX=0, TS=7)
Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654400 block=2 data=48 08 20 08 0c 72 00 02 18 00 80 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+Got RLC block, coding scheme: CS-1, length: 23 (23))
+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++
------------------------- RX : Uplink Control Block -------------------------
RX: [PCU <- BTS] TBF(TFI=0 TLLI=0xf1223344 DIR=DL STATE=WAIT RELEASE) Packet Control Ack