diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
index 9c14e3d..2011c72 100644
--- a/net/mac80211/ieee80211.c
+++ b/net/mac80211/ieee80211.c
@@ -292,9 +292,18 @@
 	struct ieee80211_sub_if_data *sdata;
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct ieee80211_if_init_conf conf;
+	struct sta_info *sta;
+	int i;
 
 	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
+	list_for_each_entry(sta, &local->sta_list, list) {
+		for (i = 0; i <  STA_TID_NUM; i++)
+			ieee80211_sta_stop_rx_ba_session(sta->dev, sta->addr,
+						i, WLAN_BACK_RECIPIENT,
+						WLAN_REASON_QSTA_LEAVE_QBSS);
+	}
+
 	netif_stop_queue(dev);
 
 	/*
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index baf53c0..740d69d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -767,6 +767,9 @@
 int ieee80211_ht_addt_info_ie_to_ht_bss_info(
 			struct ieee80211_ht_addt_info *ht_add_info_ie,
 			struct ieee80211_ht_bss_info *bss_info);
+void ieee80211_sta_stop_rx_ba_session(struct net_device *dev, u8 *da,
+				u16 tid, u16 initiator, u16 reason);
+void sta_rx_agg_session_timer_expired(unsigned long data);
 /* ieee80211_iface.c */
 int ieee80211_if_add(struct net_device *dev, const char *name,
 		     struct net_device **new_dev, int type);
diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
index 5b8f484..d5a7683 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -64,6 +64,11 @@
 #define IEEE80211_ADDBA_PARAM_TID_MASK 0x003C
 #define IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK 0xFFA0
 
+/* next values represent the buffer size for A-MPDU frame.
+ * According to IEEE802.11n spec size varies from 8K to 64K (in powers of 2) */
+#define IEEE80211_MIN_AMPDU_BUF 0x8
+#define IEEE80211_MAX_AMPDU_BUF 0x40
+
 static void ieee80211_send_probe_req(struct net_device *dev, u8 *dst,
 				     u8 *ssid, size_t ssid_len);
 static struct ieee80211_sta_bss *
@@ -1005,7 +1010,8 @@
 	struct ieee80211_mgmt *mgmt;
 	u16 capab;
 
-	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
+	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom + 1 +
+					sizeof(mgmt->u.action.u.addba_resp));
 	if (!skb) {
 		printk(KERN_DEBUG "%s: failed to allocate buffer "
 		       "for addba resp frame\n", dev->name);
@@ -1047,9 +1053,14 @@
 						size_t len)
 {
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_hw *hw = &local->hw;
+	struct ieee80211_conf *conf = &hw->conf;
 	struct sta_info *sta;
-	u16 capab, tid, timeout, ba_policy, buf_size, status;
+	struct tid_ampdu_rx *tid_agg_rx;
+	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num, status;
 	u8 dialog_token;
+	int ret = -EOPNOTSUPP;
+	DECLARE_MAC_BUF(mac);
 
 	sta = sta_info_get(local, mgmt->sa);
 	if (!sta)
@@ -1058,28 +1069,216 @@
 	/* extract session parameters from addba request frame */
 	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
 	timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
+	start_seq_num =
+		le16_to_cpu(mgmt->u.action.u.addba_req.start_seq_num) >> 4;
 
 	capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
 	ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
 	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
 	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
 
-	/* TODO - currently aggregation is declined (A-MPDU add BA request
-	* acceptance is not obligatory by 802.11n draft), but here is
-	* the entry point for dealing with it */
-#ifdef MAC80211_HT_DEBUG
-	if (net_ratelimit())
-		printk(KERN_DEBUG "Add Block Ack request arrived,"
-				   " currently denying it\n");
-#endif /* MAC80211_HT_DEBUG */
-
 	status = WLAN_STATUS_REQUEST_DECLINED;
 
+	/* sanity check for incoming parameters:
+	 * check if configuration can support the BA policy
+	 * and if buffer size does not exceeds max value */
+	if (((ba_policy != 1)
+		&& (!(conf->ht_conf.cap & IEEE80211_HT_CAP_DELAY_BA)))
+		|| (buf_size > IEEE80211_MAX_AMPDU_BUF)) {
+		status = WLAN_STATUS_INVALID_QOS_PARAM;
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		if (net_ratelimit())
+			printk(KERN_DEBUG "Block Ack Req with bad params from "
+				"%s on tid %u. policy %d, buffer size %d\n",
+				print_mac(mac, mgmt->sa), tid, ba_policy,
+				buf_size);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		goto end_no_lock;
+	}
+	/* determine default buffer size */
+	if (buf_size == 0) {
+		struct ieee80211_hw_mode *mode = conf->mode;
+		buf_size = IEEE80211_MIN_AMPDU_BUF;
+		buf_size = buf_size << mode->ht_info.ampdu_factor;
+	}
+
+	tid_agg_rx = &sta->ampdu_mlme.tid_rx[tid];
+
+	/* examine state machine */
+	spin_lock_bh(&sta->ampdu_mlme.ampdu_rx);
+
+	if (tid_agg_rx->state != HT_AGG_STATE_IDLE) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		if (net_ratelimit())
+			printk(KERN_DEBUG "unexpected Block Ack Req from "
+				"%s on tid %u\n",
+				print_mac(mac, mgmt->sa), tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		goto end;
+	}
+
+	/* prepare reordering buffer */
+	tid_agg_rx->reorder_buf =
+		kmalloc(buf_size * sizeof(struct sk_buf *), GFP_ATOMIC);
+	if ((!tid_agg_rx->reorder_buf) && net_ratelimit()) {
+		printk(KERN_ERR "can not allocate reordering buffer "
+						"to tid %d\n", tid);
+		goto end;
+	}
+	memset(tid_agg_rx->reorder_buf, 0,
+		buf_size * sizeof(struct sk_buf *));
+
+	if (local->ops->ampdu_action)
+		ret = local->ops->ampdu_action(hw, IEEE80211_AMPDU_RX_START,
+					       sta->addr, tid, start_seq_num);
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "Rx A-MPDU on tid %d result %d", tid, ret);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+
+	if (ret) {
+		kfree(tid_agg_rx->reorder_buf);
+		goto end;
+	}
+
+	/* change state and send addba resp */
+	tid_agg_rx->state = HT_AGG_STATE_OPERATIONAL;
+	tid_agg_rx->dialog_token = dialog_token;
+	tid_agg_rx->ssn = start_seq_num;
+	tid_agg_rx->head_seq_num = start_seq_num;
+	tid_agg_rx->buf_size = buf_size;
+	tid_agg_rx->timeout = timeout;
+	tid_agg_rx->stored_mpdu_num = 0;
+	status = WLAN_STATUS_SUCCESS;
+end:
+	spin_unlock_bh(&sta->ampdu_mlme.ampdu_rx);
+
+end_no_lock:
 	ieee80211_send_addba_resp(sta->dev, sta->addr, tid, dialog_token,
 				status, 1, buf_size, timeout);
 	sta_info_put(sta);
 }
 
+void ieee80211_send_delba(struct net_device *dev, const u8 *da, u16 tid,
+				u16 initiator, u16 reason_code)
+{
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_if_sta *ifsta = &sdata->u.sta;
+	struct sk_buff *skb;
+	struct ieee80211_mgmt *mgmt;
+	u16 params;
+
+	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom + 1 +
+					sizeof(mgmt->u.action.u.delba));
+
+	if (!skb) {
+		printk(KERN_ERR "%s: failed to allocate buffer "
+					"for delba frame\n", dev->name);
+		return;
+	}
+
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
+	memset(mgmt, 0, 24);
+	memcpy(mgmt->da, da, ETH_ALEN);
+	memcpy(mgmt->sa, dev->dev_addr, ETH_ALEN);
+	if (sdata->type == IEEE80211_IF_TYPE_AP)
+		memcpy(mgmt->bssid, dev->dev_addr, ETH_ALEN);
+	else
+		memcpy(mgmt->bssid, ifsta->bssid, ETH_ALEN);
+	mgmt->frame_control = IEEE80211_FC(IEEE80211_FTYPE_MGMT,
+					IEEE80211_STYPE_ACTION);
+
+	skb_put(skb, 1 + sizeof(mgmt->u.action.u.delba));
+
+	mgmt->u.action.category = WLAN_CATEGORY_BACK;
+	mgmt->u.action.u.delba.action_code = WLAN_ACTION_DELBA;
+	params = (u16)(initiator << 11); 	/* bit 11 initiator */
+	params |= (u16)(tid << 12); 		/* bit 15:12 TID number */
+
+	mgmt->u.action.u.delba.params = cpu_to_le16(params);
+	mgmt->u.action.u.delba.reason_code = cpu_to_le16(reason_code);
+
+	ieee80211_sta_tx(dev, skb, 0);
+}
+
+void ieee80211_sta_stop_rx_ba_session(struct net_device *dev, u8 *ra, u16 tid,
+					u16 initiator, u16 reason)
+{
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_hw *hw = &local->hw;
+	struct sta_info *sta;
+	int ret;
+
+	sta = sta_info_get(local, ra);
+	if (!sta)
+		return;
+
+	/* check if TID is in operational state */
+	spin_lock_bh(&sta->ampdu_mlme.ampdu_rx);
+	if (sta->ampdu_mlme.tid_rx[tid].state
+				!= HT_AGG_STATE_OPERATIONAL) {
+		spin_unlock_bh(&sta->ampdu_mlme.ampdu_rx);
+		if (net_ratelimit())
+			printk(KERN_DEBUG "rx BA session requested to stop on "
+				"inactive tid %d\n", tid);
+		sta_info_put(sta);
+		return;
+	}
+	sta->ampdu_mlme.tid_rx[tid].state =
+		HT_AGG_STATE_REQ_STOP_BA_MSK |
+		(initiator << HT_AGG_STATE_INITIATOR_SHIFT);
+		spin_unlock_bh(&sta->ampdu_mlme.ampdu_rx);
+
+	/* stop HW Rx aggregation. ampdu_action existence
+	 * already verified in session init so we add the BUG_ON */
+	BUG_ON(!local->ops->ampdu_action);
+
+	ret = local->ops->ampdu_action(hw, IEEE80211_AMPDU_RX_STOP,
+					ra, tid, EINVAL);
+	if (ret)
+		printk(KERN_DEBUG "HW problem - can not stop rx "
+				"aggergation for tid %d\n", tid);
+
+	/* shutdown timer has not expired */
+	if (initiator != WLAN_BACK_TIMER)
+		del_timer_sync(&sta->ampdu_mlme.tid_rx[tid].
+					session_timer);
+
+	/* check if this is a self generated aggregation halt */
+	if (initiator == WLAN_BACK_RECIPIENT || initiator == WLAN_BACK_TIMER)
+		ieee80211_send_delba(dev, ra, tid, 0, reason);
+
+	/* free the reordering buffer */
+	kfree(sta->ampdu_mlme.tid_rx[tid].reorder_buf);
+
+	sta->ampdu_mlme.tid_rx[tid].state = HT_AGG_STATE_IDLE;
+	sta_info_put(sta);
+}
+
+/*
+ * After receiving Block Ack Request (BAR) we activated a
+ * timer after each frame arrives from the originator.
+ * if this timer expires ieee80211_sta_stop_rx_ba_session will be executed.
+ */
+void sta_rx_agg_session_timer_expired(unsigned long data)
+{
+	/* not an elegant detour, but there is no choice as the timer passes
+	 * only one argument, and verious sta_info are needed here, so init
+	 * flow in sta_info_add gives the TID as data, while the timer_to_id
+	 * array gives the sta through container_of */
+	u8 *ptid = (u8 *)data;
+	u8 *timer_to_id = ptid - *ptid;
+	struct sta_info *sta = container_of(timer_to_id, struct sta_info,
+					 timer_to_tid[0]);
+
+	printk(KERN_DEBUG "rx session timer expired on tid %d\n", (u16)*ptid);
+	ieee80211_sta_stop_rx_ba_session(sta->dev, sta->addr, (u16)*ptid,
+					 WLAN_BACK_TIMER,
+					 WLAN_REASON_QSTA_TIMEOUT);
+}
+
+
 static void ieee80211_rx_mgmt_auth(struct net_device *dev,
 				   struct ieee80211_if_sta *ifsta,
 				   struct ieee80211_mgmt *mgmt,
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index ffe8a49..60ca078 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -104,6 +104,7 @@
 	struct sta_info *sta = container_of(kref, struct sta_info, kref);
 	struct ieee80211_local *local = sta->local;
 	struct sk_buff *skb;
+	int i;
 
 	/* free sta structure; it has already been removed from
 	 * hash table etc. external structures. Make sure that all
@@ -116,6 +117,8 @@
 	while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
 		dev_kfree_skb_any(skb);
 	}
+	for (i = 0; i <  STA_TID_NUM; i++)
+		del_timer_sync(&sta->ampdu_mlme.tid_rx[i].session_timer);
 	rate_control_free_sta(sta->rate_ctrl, sta->rate_ctrl_priv);
 	rate_control_put(sta->rate_ctrl);
 	kfree(sta);