Methods for determining a location of a client device in a wireless network having at least a first other network device with a known location are disclosed. Transmission-to-self calibrations are performed at the first other network device and/or the client device to determine RF group delay of the first other network device and/or the client device. The client device receives messages and acknowledgements from the other network devices and determines its location based on information received including the time at which it received the messages, the acknowledgements and the RF groupdelay of the first other network device. As such, the location calculation can be refined by accounting for the RF group delays of the first other network device and/or the client device.