US Patent 12137428 Synchronization of joint transmissions with multiple access points

A first access point (AP) receives a first physical layer (PHY) data unit for initiating a joint channel sounding procedure between a group of APs and one or more client stations. The first AP receives a second PHY data unit for initiating a joint transmission by the group of APs. The first AP uses training signals in the first PHY data unit and the second PHY data unit to calculate a relative timing offset. The first AP uses the relative timing offset to adjust a transmit time of a third PHY data transmitted as part of the joint transmission.