Hybrid beam-forming and space-time coding multi-user downlink transmission method in Massive MIMO (Multiple Input Multiple Output) system

Abstract

The invention discloses a hybrid beam-forming and space-time coding multi-user downlink transmission method in a Massive MIMO (Multiple Input Multiple Output) system. When a linear weighting matrix is designed, two-stage design is carried out on a covariance matrix of a channel, and owing to the high correlation of the channel, the covariance matrix of the channel has low-rank character, so that the expenditure for channel estimation can be reduced. The non-overlapping of angles of users is utilized in the aspect of effect, and the interference between the users is eliminated in the two-stage design. The conditions of independent power constraint and summation power constraint of each user are considered. Non-convexity of a problem is processed by SDR (Software Defined Radio) and alternating iteration methods, the non-convexity of the original problem is converted to a convex optimization problem, so that the effective numerical solution is carried out on the problem. In comparison with the SDR method, the alternating iteration method has lower computation complexity.

Description

Technical field [0001] The invention belongs to the field of wireless transmission technology, and particularly relates to a method for transmitting mixed beam forming and space-time coding multi-user downlink signals in a Massive MIMO system. Background technique [0002] MassiveMIMO technology has become a key technology in wireless communication 5G. By configuring a large number of antennas, the channels are approximately orthogonal, and through simple receiving and sending techniques, such as maximum ratio combining and maximum ratio transmission, multi-user interference can be eliminated and noise can be smoothed, thereby greatly improving the energy and spectrum efficiency of the system . However, the performance improvement brought by the MassiveMIMO system largely depends on the acquisition of channel information. For the TDD system, the reciprocity of uplink and downlink can be utilized, and the uplink transmission pilot can be used for channel estimation, which can be...

AI Technical Summary

Problems solved by technology

However, in the two-stage scheme in the article, after using the channel covariance matrix to complete the precoding design of the first stage, the precoding of the second stage needs to know the accurate equivalent channel, and the system complexity is still high

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