Fast handover in infrastructure mode

From: Wenhui Zhang (
Date: 2002-07-11 09:57:48 UTC


We want to implement fast handover in the IP layer in WLAN environment, where WLAN cells are connected by routers (IAPP is not considered). The problem we encountered now is that in infrastruture mode, the WLAN layer 2 handover delay is rather big, over 100ms, which is not what we expected.

One choice for us is to use ad hoc mode just to reduce the delay. but it is the real ad hoc mode, because we have STA works as a AP

So we have think of reduce the handover delay in infrastructure mode, the idea is: Let a STA join a BSS without authentication and association with the AP. This requires that a STA sends data frames without the association response, but right after synchonised with the AP and receiving the Join command from the above layer. While the AP can forward packets from the STA that is not associated.

As to security, we rely on IP layer authentication and do not care layer 2 authentication (this is the first step, later preauthentication can be used). As to association, we also rely on functions in the IP layer and in this case, association will not have much meaning to us.

I think it is quite interesting topic, but we do not have experience with this. Does anyone know the feasibility and difficulty?




 Wenhui Zhang 
 Institute of Communication Networks and Computer Engineering (IND)
 University of Stuttgart
 Pfaffenwaldring 47
 D-70569 Stuttgart, Germany

 Office Room 1.303
 Phone  +49-711-685 7964
 Fax    +49-711-685 7983

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