diff -r 34acfd7ad508 src/devices/wifi/qos-tag.cc
--- a/src/devices/wifi/qos-tag.cc	Tue Aug 25 08:52:57 2009 +0200
+++ b/src/devices/wifi/qos-tag.cc	Tue Aug 25 19:04:08 2009 +0200
@@ -44,9 +44,9 @@
 }
 
 QosTag::QosTag ():
-  m_tid (0)
+  m_tid (UP_BE)
 {}
-QosTag::QosTag (uint8_t tid):
+QosTag::QosTag (enum UserPriority tid):
   m_tid (tid)
 {}
 
@@ -65,16 +65,16 @@
 void
 QosTag::Deserialize (TagBuffer i)
 {
-  m_tid = i.ReadU8 ();
+  m_tid = (enum UserPriority) i.ReadU8 ();
 }
 
 void
-QosTag::Set (uint8_t tid)
+QosTag::Set (enum UserPriority tid)
 {
   m_tid = tid;
 }
 
-uint8_t
+enum UserPriority
 QosTag::Get () const
 {
   return m_tid;
diff -r 34acfd7ad508 src/devices/wifi/qos-tag.h
--- a/src/devices/wifi/qos-tag.h	Tue Aug 25 08:52:57 2009 +0200
+++ b/src/devices/wifi/qos-tag.h	Tue Aug 25 19:04:08 2009 +0200
@@ -26,6 +26,23 @@
 
 class Tag;
 
+
+/**
+ * As per IEEE Std. 802.11-2007, Section 6.1.1.1.1, for QoS data the
+ * the Traffic ID (TID) value corresponds to one of the User Priority (UP)
+ * values defined by the IEEE Std. 802.1D-2004, Annex G, table G-2..
+ */
+enum UserPriority {
+  UP_BK = 1, /**< background  */
+  UP_BE = 0, /**< best effort (default) */
+  UP_EE = 3, /**< excellent effort  */
+  UP_CL = 4, /**< controlled load */
+  UP_VI = 5, /**< video, < 100ms latency and jitter */
+  UP_VO = 6, /**< voice, < 10ms latency and jitter */
+  UP_NC = 7  /**< network control */
+};
+  
+
 class QosTag : public Tag
 {
 public:
@@ -33,16 +50,16 @@
   virtual TypeId GetInstanceTypeId (void) const;
   
   QosTag ();
-  QosTag (uint8_t tid);
+  QosTag (UserPriority tid);
   virtual void Serialize (TagBuffer i) const;
   virtual void Deserialize (TagBuffer i);
   virtual uint32_t GetSerializedSize () const;
   virtual void Print (std::ostream &os) const;
 
-  uint8_t Get (void) const;
-  void Set (uint8_t tid);
+  UserPriority Get (void) const;
+  void Set (UserPriority tid);
 private:
-  uint8_t m_tid;
+  UserPriority m_tid;
 };
 
 } //namespace ns3