diff --git a/src/bts.cpp b/src/bts.cpp
index b2336b88..6bdb4f3f 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -892,6 +892,9 @@ void gprs_rlcmac_pdch::rcv_control_dl_ack_nack(Packet_Downlink_Ack_Nack_t *ack_n
 	struct gprs_rlcmac_dl_tbf *tbf;
 	int rc;
 	struct pcu_l1_meas meas;
+	uint8_t bits_data[RLC_GPRS_WS/8];
+	bitvec bits;
+	int bsn_begin, bsn_end;
 
 	tfi = ack_nack->DOWNLINK_TFI;
 	tbf = bts()->dl_tbf_by_poll_fn(fn, trx_no(), ts_no);
@@ -918,10 +921,17 @@ void gprs_rlcmac_pdch::rcv_control_dl_ack_nack(Packet_Downlink_Ack_Nack_t *ack_n
 	LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] %s Packet Downlink Ack/Nack\n", tbf_name(tbf));
 	tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
 
+	bits.data = bits_data;
+	bits.data_len = sizeof(bits_data);
+	bits.cur_bit = 0;
+
+	Decoding::decode_gprs_acknack_bits(
+		&ack_nack->Ack_Nack_Description, &bits,
+		&bsn_begin, &bsn_end, &tbf->m_window);
+
 	rc = tbf->rcvd_dl_ack(
 		ack_nack->Ack_Nack_Description.FINAL_ACK_INDICATION,
-		ack_nack->Ack_Nack_Description.STARTING_SEQUENCE_NUMBER,
-		ack_nack->Ack_Nack_Description.RECEIVED_BLOCK_BITMAP);
+		bsn_begin, &bits);
 	if (rc == 1) {
 		tbf_free(tbf);
 		return;
diff --git a/src/decoding.cpp b/src/decoding.cpp
index 7fa77d7d..e2e22321 100644
--- a/src/decoding.cpp
+++ b/src/decoding.cpp
@@ -328,6 +328,18 @@ void Decoding::extract_rbb(const uint8_t *rbb, char *show_rbb)
 	show_rbb[64] = '\0';
 }
 
+void Decoding::extract_rbb(const struct bitvec *rbb, char *show_rbb)
+{
+	unsigned int i;
+	for (i = 0; i < rbb->cur_bit; i++) {
+		uint8_t bit;
+		bit = bitvec_get_bit_pos(rbb, i);
+		show_rbb[i] = bit == 1 ? 'R' : 'I';
+	}
+
+	show_rbb[i] = '\0';
+}
+
 int Decoding::rlc_parse_ul_data_header(struct gprs_rlc_data_info *rlc,
 	const uint8_t *data, GprsCodingScheme cs)
 {
@@ -534,9 +546,34 @@ int Decoding::decode_egprs_acknack_bits(const EGPRS_AckNack_Desc_t *desc,
 	urbb.data_len = sizeof(desc->URBB);
 
 	for (int i = urbb_len; i > 0; i--) {
-		/* Set bit at the appropriate position (see 3GPP TS 04.60 12.3.1) */
+		/* Set bit at the appropriate position (see 3GPP TS 44.060 12.3.1) */
 		int is_ack = bitvec_get_bit_pos(&urbb, i-1);
-		bitvec_set_bit(bits, is_ack ? ONE : ZERO);
+		bitvec_set_bit(bits, is_ack == 1 ? ONE : ZERO);
+	}
+
+	return num_blocks;
+}
+
+int Decoding::decode_gprs_acknack_bits(const Ack_Nack_Description_t *desc,
+	bitvec *bits, int *bsn_begin, int *bsn_end, gprs_rlc_dl_window *window)
+{
+	int urbb_len = RLC_GPRS_WS;
+	int num_blocks;
+	struct bitvec urbb;
+
+	num_blocks = urbb_len;
+
+	*bsn_end   = desc->STARTING_SEQUENCE_NUMBER;
+	*bsn_begin = window->mod_sns(*bsn_end - RLC_GPRS_WS);
+
+	urbb.cur_bit = 0;
+	urbb.data = (uint8_t *)desc->RECEIVED_BLOCK_BITMAP;
+	urbb.data_len = sizeof(desc->RECEIVED_BLOCK_BITMAP);
+
+	for (int i = urbb_len; i > 0; i--) {
+		/* Set bit at the appropriate position (see 3GPP TS 44.060 12.3) */
+		int is_ack = bitvec_get_bit_pos(&urbb, i-1);
+		bitvec_set_bit(bits, is_ack == 1 ? ONE : ZERO);
 	}
 
 	return num_blocks;
diff --git a/src/decoding.h b/src/decoding.h
index 99cb3187..58ecd18e 100644
--- a/src/decoding.h
+++ b/src/decoding.h
@@ -42,6 +42,7 @@ public:
 	static uint8_t get_egprs_ms_class_by_capability(MS_Radio_Access_capability_t *cap);
 
 	static void extract_rbb(const uint8_t *rbb, char *extracted_rbb);
+	static void extract_rbb(const struct bitvec *rbb, char *show_rbb);
 
 	static int rlc_parse_ul_data_header(struct gprs_rlc_data_info *rlc,
 		const uint8_t *data, GprsCodingScheme cs);
@@ -57,4 +58,8 @@ public:
 		const EGPRS_AckNack_Desc_t *desc,
 		struct bitvec *bits, int *bsn_begin, int *bsn_end,
 		struct gprs_rlc_dl_window *window);
+	static int decode_gprs_acknack_bits(
+		const Ack_Nack_Description_t *desc,
+		bitvec *bits, int *bsn_begin, int *bsn_end,
+		gprs_rlc_dl_window *window);
 };
diff --git a/src/rlc.cpp b/src/rlc.cpp
index 1a8efdf6..27e8a5f2 100644
--- a/src/rlc.cpp
+++ b/src/rlc.cpp
@@ -114,6 +114,45 @@ static uint16_t bitnum_to_bsn(int bitnum, uint16_t ssn)
 	return (ssn - 1 - bitnum);
 }
 
+void gprs_rlc_dl_window::update(BTS *bts, const struct bitvec *rbb,
+			uint16_t first_bsn, uint16_t *lost,
+			uint16_t *received)
+{
+	unsigned num_blocks = rbb->cur_bit;
+	unsigned bsn;
+
+	/* first_bsn is in range V(A)..V(S) */
+
+	/* All BSN before first_bsn are implicitly acknowledged */
+	for (bsn = v_a(); bsn != first_bsn; bsn = mod_sns(bsn + 1)) {
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- got implicit ack for BSN=%d\n", bsn);
+		if (!m_v_b.is_acked(bsn))
+			*received += 1;
+		m_v_b.mark_acked(bsn);
+	}
+
+	for (unsigned int bitpos = 0; bitpos < num_blocks; bitpos++) {
+		bool is_ack;
+		bsn = mod_sns(first_bsn + bitpos);
+		if (bsn == mod_sns(v_a() - 1))
+			break;
+
+		is_ack = bitvec_get_bit_pos(rbb, bitpos) == 1;
+
+		if (is_ack) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- got ack for BSN=%d\n", bsn);
+			if (!m_v_b.is_acked(bsn))
+				*received += 1;
+			m_v_b.mark_acked(bsn);
+		} else {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- got NACK for BSN=%d\n", bsn);
+			m_v_b.mark_nacked(bsn);
+			bts->rlc_nacked();
+			*lost += 1;
+		}
+	}
+}
+
 void gprs_rlc_dl_window::update(BTS *bts, char *show_rbb, uint16_t ssn,
 			uint16_t *lost, uint16_t *received)
 {
diff --git a/src/rlc.h b/src/rlc.h
index 76af4e10..3f599d47 100644
--- a/src/rlc.h
+++ b/src/rlc.h
@@ -32,6 +32,7 @@
 #define RLC_EGPRS_MAX_WS 1024 /* min window size */
 #define RLC_EGPRS_SNS 2048 /* EGPRS, must be power of 2 */
 #define RLC_MAX_SNS  RLC_EGPRS_SNS
+#define RLC_MAX_WS   RLC_EGPRS_MAX_WS
 #define RLC_MAX_LEN 74 /* MCS-9 data unit */
 
 struct BTS;
@@ -173,6 +174,9 @@ struct gprs_rlc_dl_window {
 	int mark_for_resend();
 	void update(BTS *bts, char *show_rbb, uint16_t ssn,
 			uint16_t *lost, uint16_t *received);
+	void update(BTS *bts, const struct bitvec *rbb,
+			uint16_t first_bsn, uint16_t *lost,
+			uint16_t *received);
 	int move_window();
 	void show_state(char *show_rbb);
 	int count_unacked();
diff --git a/src/tbf.h b/src/tbf.h
index cd982739..11e1fc73 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -344,6 +344,7 @@ struct gprs_rlcmac_dl_tbf : public gprs_rlcmac_tbf {
 			const uint8_t *data, const uint16_t len);
 
 	int rcvd_dl_ack(uint8_t final, uint8_t ssn, uint8_t *rbb);
+	int rcvd_dl_ack(uint8_t final_ack, unsigned first_bsn, struct bitvec *rbb);
 	struct msgb *create_dl_acked_block(uint32_t fn, uint8_t ts);
 	void request_dl_ack();
 	bool need_control_ts() const;
@@ -395,6 +396,7 @@ protected:
 	struct msgb *create_dl_acked_block(const uint32_t fn, const uint8_t ts,
 					const int index);
 	int update_window(const uint8_t ssn, const uint8_t *rbb);
+	int update_window(unsigned first_bsn, const struct bitvec *rbb);
 	int maybe_start_new_window();
 	bool dl_window_stalled() const;
 	void reuse_tbf();
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index e742c799..ac14c478 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -644,9 +644,9 @@ int gprs_rlcmac_dl_tbf::analyse_errors(char *show_rbb, uint8_t ssn,
 {
 	gprs_rlc_data *rlc_data;
 	uint16_t lost = 0, received = 0, skipped = 0;
-	char info[65];
-	memset(info, '.', sizeof(info));
-	info[64] = 0;
+	char info[RLC_MAX_WS + 1];
+	memset(info, '.', m_window.ws());
+	info[m_window.ws()] = 0;
 	uint16_t bsn = 0;
 	unsigned received_bytes = 0, lost_bytes = 0;
 	unsigned received_packets = 0, lost_packets = 0;
@@ -717,6 +717,71 @@ int gprs_rlcmac_dl_tbf::analyse_errors(char *show_rbb, uint8_t ssn,
 	return lost * 100 / (lost + received);
 }
 
+int gprs_rlcmac_dl_tbf::update_window(unsigned first_bsn,
+	const struct bitvec *rbb)
+{
+	int16_t dist; /* must be signed */
+	uint16_t lost = 0, received = 0;
+	char show_v_b[RLC_MAX_SNS + 1];
+	char show_rbb[RLC_MAX_SNS + 1];
+	int error_rate;
+	struct ana_result ana_res;
+	unsigned num_blocks = rbb->cur_bit;
+	unsigned behind_last_bsn = m_window.mod_sns(first_bsn + num_blocks);
+
+	Decoding::extract_rbb(rbb, show_rbb);
+	/* show received array in debug */
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- ack:  (BSN=%d)\"%s\""
+		"(BSN=%d)  R=ACK I=NACK\n", first_bsn,
+		show_rbb, m_window.mod_sns(behind_last_bsn - 1));
+
+	/* apply received array to receive state (SSN-64..SSN-1) */
+	/* calculate distance of ssn from V(S) */
+	dist = m_window.mod_sns(m_window.v_s() - behind_last_bsn);
+	/* check if distance is less than distance V(A)..V(S) */
+	if (dist >= m_window.distance()) {
+		/* this might happpen, if the downlink assignment
+		 * was not received by ms and the ack refers
+		 * to previous TBF
+		 * FIXME: we should implement polling for
+		 * control ack!*/
+		LOGP(DRLCMACDL, LOGL_NOTICE, "- ack range is out of "
+			"V(A)..V(S) range %s Free TBF!\n", tbf_name(this));
+		return 1; /* indicate to free TBF */
+	}
+
+	error_rate = analyse_errors(show_rbb, behind_last_bsn, &ana_res);
+
+	if (bts_data()->cs_adj_enabled && ms())
+		ms()->update_error_rate(this, error_rate);
+
+	m_window.update(bts, rbb, first_bsn, &lost, &received);
+
+	/* report lost and received packets */
+	gprs_rlcmac_received_lost(this, received, lost);
+
+	/* Used to measure the leak rate */
+	gprs_bssgp_update_bytes_received(ana_res.received_bytes,
+		ana_res.received_packets + ana_res.lost_packets);
+
+	/* raise V(A), if possible */
+	m_window.raise(m_window.move_window());
+
+	/* show receive state array in debug (V(A)..V(S)-1) */
+	m_window.show_state(show_v_b);
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- V(B): (V(A)=%d)\"%s\""
+		"(V(S)-1=%d)  A=Acked N=Nacked U=Unacked "
+		"X=Resend-Unacked I=Invalid\n",
+		m_window.v_a(), show_v_b,
+		m_window.v_s_mod(-1));
+
+	if (state_is(GPRS_RLCMAC_FINISHED) && m_window.window_empty()) {
+		LOGP(DRLCMACDL, LOGL_NOTICE, "Received acknowledge of "
+			"all blocks, but without final ack "
+			"inidcation (don't worry)\n");
+	}
+	return 0;
+}
 
 int gprs_rlcmac_dl_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 {
@@ -825,6 +890,18 @@ int gprs_rlcmac_dl_tbf::release()
 }
 
 
+int gprs_rlcmac_dl_tbf::rcvd_dl_ack(uint8_t final_ack, unsigned first_bsn,
+	struct bitvec *rbb)
+{
+	LOGP(DRLCMACDL, LOGL_DEBUG, "%s downlink acknowledge\n", tbf_name(this));
+
+	if (!final_ack)
+		return update_window(first_bsn, rbb);
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- Final ACK received.\n");
+	return maybe_start_new_window();
+}
+
 int gprs_rlcmac_dl_tbf::rcvd_dl_ack(uint8_t final_ack, uint8_t ssn, uint8_t *rbb)
 {
 	LOGP(DRLCMACDL, LOGL_DEBUG, "%s downlink acknowledge\n", tbf_name(this));