diff --git a/sys/net80211/ieee80211_ht.h b/sys/net80211/ieee80211_ht.h
--- a/sys/net80211/ieee80211_ht.h
+++ b/sys/net80211/ieee80211_ht.h
@@ -240,5 +240,9 @@
 int	ieee80211_ampdu_tx_request_active_ext(struct ieee80211_node *ni,
 	    int tid, int status);
 void	ieee80211_htinfo_notify(struct ieee80211vap *vap);
+int	ieee80211_ht_get_node_ampdu_density(struct ieee80211_node *ni);
+int	ieee80211_ht_get_node_ampdu_limit(struct ieee80211_node *ni);
+bool	ieee80211_ht_check_tx_shortgi_20(struct ieee80211_node *ni);
+bool	ieee80211_ht_check_tx_shortgi_40(struct ieee80211_node *ni);
 
 #endif /* _NET80211_IEEE80211_HT_H_ */
diff --git a/sys/net80211/ieee80211_ht.c b/sys/net80211/ieee80211_ht.c
--- a/sys/net80211/ieee80211_ht.c
+++ b/sys/net80211/ieee80211_ht.c
@@ -3604,3 +3604,80 @@
 	frm[5] = BCM_OUI_HTINFO;
 	return ieee80211_add_htinfo_body(frm + 6, ni);
 }
+
+/*
+ * Get the HT density for the given 802.11n node.
+ *
+ * Take into account the density advertised from the peer.
+ * Larger values are longer A-MPDU density spacing values, and
+ * we want to obey them per station if we get them.
+ */
+int
+ieee80211_ht_get_node_ampdu_density(struct ieee80211_node *ni)
+{
+	struct ieee80211vap *vap = ni->ni_vap;
+	int peer_mpdudensity;
+
+	peer_mpdudensity =
+	    _IEEE80211_MASKSHIFT(ni->ni_htparam, IEEE80211_HTCAP_MPDUDENSITY);
+	if (vap->iv_ampdu_density > peer_mpdudensity)
+		peer_mpdudensity = vap->iv_ampdu_density;
+	return peer_mpdudensity;
+}
+
+/*
+ * Get the transmit A-MPDU limit for the given 802.11n node.
+ *
+ * Take into account the limit advertised from the peer.
+ * Smaller values indicate smaller maximum A-MPDU sizes, and
+ * should be used when forming an A-MPDU to the given peer.
+ */
+int
+ieee80211_ht_get_node_ampdu_limit(struct ieee80211_node *ni)
+{
+	struct ieee80211vap *vap = ni->ni_vap;
+	int peer_mpdulimit;
+
+	peer_mpdulimit =
+	    _IEEE80211_MASKSHIFT(ni->ni_htparam, IEEE80211_HTCAP_MAXRXAMPDU);
+
+	return MIN(vap->iv_ampdu_limit, peer_mpdulimit);
+}
+
+/*
+ * Return true if short-GI is available when transmitting to
+ * the given node at 20MHz.
+ *
+ * Ensure it's configured and available in the VAP / driver as
+ * well as the node.
+ */
+bool
+ieee80211_ht_check_tx_shortgi_20(struct ieee80211_node *ni)
+{
+	struct ieee80211vap *vap = ni->ni_vap;
+	struct ieee80211com *ic = ni->ni_ic;
+
+	/* Note: always assume the node can do HT20 here */
+	return (ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20)
+	    && (ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20)
+	    && (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20);
+}
+
+/*
+ * Return true if short-GI is available when transmitting to
+ * the given node at 40MHz.
+ *
+ * Ensure it's configured and available in the VAP / driver as
+ * well as the node.
+ */
+bool
+ieee80211_ht_check_tx_shortgi_40(struct ieee80211_node *ni)
+{
+	struct ieee80211vap *vap = ni->ni_vap;
+	struct ieee80211com *ic = ni->ni_ic;
+
+	return (ni->ni_chw == 40)
+	    && (ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40)
+	    && (ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40)
+	    && (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40);
+}