Classical 802.11 rate adaptation algorithms rely on feedback from the receiver to correctly choose a sending rate, typically in the form of acknowledgments (ACKs). In the absence of such frames, novel techniques are required for rate selection. We present a novel On-Demand Feedback Rate Adaptation algorithm (OFRA) that works with ACK-less traffic. Feedback information is sent on-demand using a control frame to explicitly inform the transmitter about which bit rate to use on subsequent data frames. This approach guarantees standard conformity and exhibits fast and accurate bit rate adaptation at the cost of a modest overhead increase. We evaluate the performance of OFRA against various state-of-the-art rate adaptation schemes by means of simulations. If ACK frames are to be transmitted, OFRA performs better than related work in most considered scenarios, and on par in the others. In the absence of ACKs, OFRA provides large goodput gains under good channel conditions and comparable goodput in other situations. ; QC 20131213