The performance of RFID anti-collision protocols that are based on framed 
ALOHA depends on a transmission scheme that controls access to the shared 
channel. In this paper, we outline the characteristics of the RFID domain that 
impact the performance of such transmission schemes and compare four different 
transmission strategies. A novel technique introduced in this paper that 
recursively estimates the backlog on a slot-by-slot basis exhibits a superior 
performance in our simulations. The results also illustrate that our 
implementation of the Q algorithm proposed in [2] only performs well, if the 
frame size changes are restricted to incremental updates.