1. In a wireless communication system comprising a main transceiver and a remote transceiver capable of receiving signals from and transmitting signals to the s main transceiver, the main transceiver comprising an array of transmit antenna elements, and at least one receive antenna element, each transmit antenna element being part of a transmit electronics chain for transmitting a transmit apparatus signal using the transmit antenna element, and each receive antenna element being part of a receiver apparatus chain for receiving a received antenna signal from the receive antenna element, the main transceiver and the remote transceiver designed for mutual communication using waveforms conforming to an air interface standard, a method for estimating the downlink signature for the remote transceiver, the method comprising: (a) transmitting a set of one or more downlink calibration waveforms from the main transceiver via the transmit antenna array to the remote transceiver, the set of downlink calibration waveforms substantially conforming to the air interface standard; (b) processing the signals received at the remote transceiver corresponding to the downlink calibration waveforms, the processing to determine downlink signature related signals related to the downlink signature for the remote transceiver; (c) transmitting the downlink signature related signals from the remote transceiver to the main transceiver using waveforms substantially conforming to the air interface standard; and (d) determining the downlink signature of the remote transceiver from the downlink signature related signals received at the main transceiver.