An access point (AP) in a wireless local area network (WLAN) uses a protocol to determine frequency/time resource allocations of resource units (RUs) in parallel with data transfer to and from WLAN stations (STAs). The AP generates a sounding table associating STAs with RUs for uplink (UL) and downlink (DL). The AP processes the sounding table to create a channel map table and then the AP allocates particular RUs to particular STAs. The STAs then receive and transmit data from and to the AP over the allocated RUs. This approach achieves good throughput while reducing the use of signaling and pilot overhead associated with channel sounding. To avoid interruption of ongoing transmissions, a newly arriving STA is grouped and sounded with other STAs. The protocol includes a joint sounding and data epoch followed by a determination of the channel map table.