A base station apparatus of mobile communication system is provided, including an antenna system including first antenna for transceiving signals for a first path among MIMO paths, and a second antenna for transceiving signals for a second path among the MIMO paths, a first duplexer including transmission filter for processing the transmitted signal of first path and reception filter for processing the received signal of second path, a second duplexer including reception filter for processing the received signal of first path and transmission filter for processing the transmitted signal of second path, and a path change unit for providing the transmitted signal provided from the first duplexer to the first antenna and the received signal provided from the first antenna to the second duplexer and to provide the transmitted signal from the second duplexer to the second antenna and the received signal from the second antenna to the first duplexer.

According to some embodiments, an apparatus for generating multiple variable frequency and phase locked clock signals comprises complex tuners, digital up-samplers, image isolation filters, quadrature modulators, a combiner, a DAC, a local oscillator, and an analog filter. The complex tuners tune multiple digital baseband signals. The up-samplers interpolate the complex tuned digital signals such that one of the up-sampled images of each of the complex tuned digital signals corresponds to a desired frequency. The image isolation filters isolate images corresponding to the desired frequencies. The quadrature modulators convert the isolated images of the complex tuned digital signals into real digital signals. The combiner combines the real digital signals into a combined real digital signal. The DAC, driven by the local oscillator, converts the combined real digital signal into an analog clock signal. The analog filter then filters the analog clock signal to select images located at the desired frequencies.

A method and apparatus automatically switch a vehicle radio frequency. The method includes: receiving, by a first tuner, a first signal at a current frequency at which listening is being performed in a vehicle; determining whether an electric field condition of a second signal received at an alternative frequency meets a first requirement; determining whether a similarity between the first signal and the second signal meets a second requirement in response to a determination that the electric field condition of the second signal meets the first requirement; and automatically switching a reception frequency of the vehicle radio to the alternative frequency in response to a determination that the similarity between the first signal and the second signal meets the second requirement. The first requirement and the second requirement are changed in consideration of noise caused by an electric power steering system of the vehicle.