Abstract: A method for antenna calibration for an active antenna system is disclosed. According to an embodiment, test signals are generated for multiple antennas of the active antenna system. The test signals are transmitted via the multiple antennas. A first signal that results from the transmission of the test signals is received over the air. A second signal is received from a coupler network of the active antenna system. The coupler network is configured to generate coupled signals of the test signals and combine the coupled signals into the second signal. Calibration information for compensating an influence of the coupler network is determined based on the first and second signals. An active antenna system is also disclosed for use in antenna calibration.

Abstract: In one example aspect, a method is provided of preparing a symbol for transmission, the method comprising applying a window function to a symbol to generate a modified symbol, wherein a property of the window function is based on a channel length of a transmission channel over which the modified symbol is to be transmitted, and causing the modified symbol to be transmitted over the transmission channel.

Abstract: A method for antenna calibration for an active antenna system is disclosed. According to an embodiment, test signals are generated for multiple antennas of the active antenna system. The test signals are transmitted via the multiple antennas. A first signal that results from the transmission of the test signals is received over the air. A second signal is received from a coupler network of the active antenna system. The coupler network is configured to generate coupled signals of the test signals and combine the coupled signals into the second signal. Calibration information for compensating an influence of the coupler network is determined based on the first and second signals. An active antenna system is also disclosed for use in antenna calibration.

Abstract: A method for antenna calibration for an active antenna system is disclosed. According to an embodiment, test signals are generated for multiple antennas of the active antenna system. The test signals are transmitted via the multiple antennas. A first signal that results from the transmission of the test signals is received over the air. A second signal is received from a coupler network of the active antenna system. The coupler network is configured to generate coupled signals of the test signals and combine the coupled signals into the second signal. Calibration information for compensating an influence of the coupler network is determined based on the first and second signals. An active antenna system is also disclosed for use in antenna calibration.

Abstract: In one example aspect, a method is provided of preparing a symbol for transmission, the method comprising applying a window function to a symbol to generate a modified symbol, wherein a property of the window function is based on a channel length of a transmission channel over which the modified symbol is to be transmitted, and causing the modified symbol to be transmitted over the transmission channel.

Abstract: A method for antenna calibration for an active antenna system is disclosed. According to an embodiment, test signals are generated for multiple antennas of the active antenna system. The test signals are transmitted via the multiple antennas A first signal that results from the transmission of the test signals is received over the air. A second signal is received from a coupler network of the active antenna system. The coupler network is configured to generate coupled signals of the test signals and combine the coupled signals into the second signal. Calibration information for compensating an influence of the coupler network is determined based on the first and second signals. An active antenna system is also disclosed for use in antenna calibration.

Abstract: The embodiments disclose a radio frequency loop test method and apparatus for testing frequency division duplexing transceiver in a radio communication system. The apparatus comprises a first directional coupling means and a mixer. The first directional coupling means is coupled with a duplex filter to receive, at a first port, a test signal from a transmitter via the duplex filter; the mixer is coupled with first directional coupling means on both sides to receive the test signal from a second port of the first directional coupling means, convert the frequency of the test signal from the transmitter to a frequency that is receivable by a receiver, and to output the converted test signal to the first directional coupling means, and the first directional coupling means is coupled to receive, at a third port, the converted test signal from the mixer and output, at the first port, the converted test signal to the receiver via the duplex filter.