This paper presents an adaptive control of the request access bandwidth of DQRUMA (distributed queuing request update multiple access) for providing QoS for multimedia traffic in a W-ATM system. Dynamic conversion of the transmission channel to multiple request access channels is applied when there is a large number of backlogged users. The protocol has been simulated in conjunction with a type-II hybrid-ARQ protocol based on punctured RS codes. The analysis was carried out for an OFDM scheme with QPSK modulation on each carrier. The hidden Markov model is used for modelling the physical layer of the system.