During a first time interval, an access point transmits orthogonal frequency division multiplexing (OFDM) signals using a first cyclic prefix length. The access point selects a second cyclic prefix length based, at least in part, on the load of the access point. The access point transmits OFDM signals using the second cyclic prefix length during a second time interval. The load of the access point may be determined based on the amount of downlink data being buffered in the access point for transmission to one or more user devices.