A pilot allocation method for a multi-cell multi-user massive MIMO system

Abstract

The invention discloses a pilot frequency distribution method for a multi-cell multi-user large-scale MIMO system. According to a large-scale fading factor, users of all cells are classified into a center user group and an edge user group; secondary screening is carried out on users in the edge user group; because large-scale fading factors between the users in the center user group and base stations of cells are small and spatial distances between the center user groups of the adjacent cells are long, users in the center user group of all cells reuse a pilot frequency sequence set; and because large-scale fading factors between the users in the edge user group and base stations of the cells are large and spatial distances between the edge user groups of the adjacent cells are short, pilot frequency sequences orthogonal to each other are distributed to the edge user groups of different cells. The method disclosed by the invention has the following characteristics: the requirement on the pilot frequency sequence set scale as well as the pilot frequency resource costs is reduced; pilot pollution from adjacent cells can be inhibited; the channel estimation precision is improved; and thus the system performances are enhanced.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a method for allocating pilot frequencies of a multi-cell multi-user massive MIMO system. Background technique [0002] A massive MIMO system is also called a multi-antenna array. By configuring a large-scale antenna array on the base station side, a wealth of spatial freedom is obtained, and the same time-frequency resources are used to provide communication services for multiple users. Each user can choose to access multiple antenna units. , which can not only increase the density of user connections, but also improve energy efficiency and system capacity. Compared with the traditional MIMO that only configures small and medium-scale antenna arrays, massive MIMO technology has many advantages: First, the asymptotic analysis based on random matrix theory shows that as the number of base station antennas increases, the small-scale fading effect of the wireless channel can be...

AI Technical Summary

Problems solved by technology

However, in massive MIMO systems, due to the high dimensionality of channel estimation, the computational complexity of blind channel estimation algorithms is extremely high, making it difficult to apply, so pilot-assisted channel estimation is mainly used

However, in mobile communication applications, the radio wave propagation environment is complex and the channel coherence time is short, resulting in the limitation of the length of the pilot sequence and the size of the pilot set, and the pilot pollution caused by the reuse of pilots in adjacent cells will cause channel estimation deviations

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