| CPC H01Q 5/335 (2015.01) [H04B 7/0652 (2013.01); H04B 7/0691 (2013.01); H04L 5/0048 (2013.01)] | 21 Claims |
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1. An apparatus for wireless communication, comprising:
a plurality of antennas including at least one transmit antenna and at least one receive antenna;
a plurality of tuners corresponding to the plurality of antennas;
an amplifier;
an antenna switch array coupled to the plurality of antennas;
a directional coupler coupled between the amplifier and the antenna switch array; and
a controller configured to:
control the antenna switch array to sequentially select each antenna in the plurality of antennas so as to transmit a reference signal configured to be used by a base station to estimate a downlink wireless channel from the base station to the apparatus and amplified by the amplifier from the antenna and to cause the directional coupler to produce a reflected signal from the antenna; and
determine a reflection coefficient for each antenna responsive to a reflected signal from the antenna, wherein the controller is further configured to adjust each tuner to improve an impedance matching to a corresponding one of the antennas, and wherein the controller is further configured to control the amplifier to transmit the reference signal in intervals separated by guard periods, and wherein the reflection coefficient for each antenna is determined within a duration of an interval in which the antenna transmits the reference signal.
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