This paper presents a novel calibration method that equalizes the impulse responses of all the Radio Frequency (RF) modules\nof an antenna array system operating in Long-Term Evolution (LTE) evolved NodeB (eNB). The proposed technique utilizes the\nZadoff-Chu (Z-C) sequence of the Primary Synchronization Signal (PSS) and Sounding Reference Signal (SRS) that are available\nin every LTE data frame for downlink and uplink, respectively, for estimating and compensating the differences in the impulse\nresponses among the RF modules. The proposed calibration method is suitable for wide bandwidth signal environments of LTE\nbecause it equalizes the impulse response of each RF module, which is ultimately equivalent to compensate the phase and amplitude\ndifferences among RF modules for the entire frequency band. In addition, the proposed method is applicable while the target eNB is\ntransmitting or receiving a data stream. From various experimental tests obtained from a test-bed implemented with 2 RF modules,\nit has been verified that the proposed method provides a reliable calibration for Release 10 Time Division Duplex (TDD) LTE signals.\nPhase errors after the calibration in our test-bed have been found to be about 2.418âË?Ë? and 2.983âË?Ë? for downlink and uplink, respectively.
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