We propose a statistical multiplexing based hybrid frequency hopping orthogonal frequency division multiple access (HFH-OFDMA) system to increase the downlink user capacity of orthogonal frequency division multiplexing (OFDM) based ultrawideband (UWB) indoor radio access networks (RANs). Downlink user capacity is defined as the maximum allowable number of users served with a given data rate in a piconet. The HFH-OFDMA system accommodates more users than the conventional FH-OFDMA system by using statistical multiplexing. In OFDM based UWB indoor RANs, the downlink user capacity of the HFH-OFDMA system is limited by either the total number of available subcarriers in a piconet (resource limited) or FCC UWB emission limit (power limited). Simulation results show that the proposed HFH-OFDMA system which operates in 3.168 GHz ∼ 3.696 GHz band accommodates 256 users with a data rate of 532.5 kb/s in OFDM based UWB indoor RANs.