Reciprocity loss compensation method of 2*2 TDD-MIMO system channel

Abstract

The invention discloses a reciprocity loss compensation method of a 2*2 TDD-MIMO system channel, which mainly solves the problem of channel reciprocity loss caused by in-phase / orthogonal I / Q imbalance in a TDD-MIMO system. In the method, a base station BS and a mobile station MS first measure respectively received direction channels to obtain channel state information CSI of an uplink and a downlink; then converging the CSI of the two links to the BS, and the BS calculates the calibration matrixes respectively used for the BS and the MS; sending the calibration matrix used by the MS to the MS; and when in formal data transmission, the BS and the MS use the respective calibration matrixes to pre-process signals to be sent so as to maintain the channel reciprocity of the uplink and the downlink. The method has the advantages of easiness, good effect and little spending of the system, and is applicable in compensating for the loss of the TDD-MIMO system channel caused by I / Q imbalance.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to link compensation, in particular to a compensation method for the problem of loss of channel reciprocity caused by I / Q imbalance in a 2×2 TDD-MIMO system, which is applied to existing I / Q unbalanced 2×2 TDD-MIMO mobile communication system. Background technique: [0002] Transceivers based on direct conversion structures have received extensive attention in recent years. Compared with the traditional superheterodyne structure, the direct conversion structure omits the link of intermediate frequency processing, and directly realizes the mutual conversion of baseband signals and radio frequency signals, which has significantly improved in terms of volume, power consumption and integration, so it has become a communication A development direction of equipment design. But there are also some problems with the direct conversion structure, one of which is I / Q imbalance. Since b...

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Problems solved by technology

Otherwise, the system performance will be severely damaged, making channel reciprocity, an inherent advantage of the TDD system, not only unusable, but even an unfavorable factor restricting system performance.

At present, the research on the impact of I / Q imbalance in the field of high-speed wireless communication is basically limited to the receiving end of the OFDM system, and only compensates for the loss of orthogonality between OFDM subcarriers caused by it, but cannot compensate for the loss of orthogonality between the transmitting end and the receiving end. It compensates for the loss of reciprocity of the TDD-MIMO system with I / Q imbalance at both ends, which will lead to deviations in the precoding operation in the TDD-MIMO system due to the loss of reciprocity of the uplink and downlink channels, making the system greatly reduced capacity

At the same time, in the case of only considering the I / Q imbalance of the receiving end, for the MS, the compensation of the I / Q imbalance needs to perform the same processing as that of the BS, which will increase the system complexity of the MS

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