Information transmission method for multi-user MIMO relay system

Abstract

The invention relates to an information transmission method for a multi-user MIMO relay system. The information transmission method comprises that: a first user sets a precoding matrix K according to CSI, wherein the precoding matrix K is provided with a twiddle factor matrix K used for selecting the alignment direction in the alignment space of an eigen direction when performing singular value decomposition (SCD) on a channel matrix; the first user processes pre-sending information according to the precoding matrix in order to form a sending matrix and sends the sending matrix to a relay; the first user receives a broadcast signal transmitted from the relay; and the first user processes the broadcast signal according to the precoding matrix in order to obtain information transmitted from multiple second users. The information transmission method designs the eigen direction alignment precoding and the twiddle factor matrix by means of the SVD, performs decoding by means of a simple ZF decoding algorithm so as to effectively improve decoding performance when good transmission channel relevance is provided, and has a physical layer safe transmission characteristic.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an information transmission method of a multi-user MIMO relay system. Background technique [0002] Multiple-Input Multiple-Output (MIMO for short) and relay technology, as important technical means of the third generation mobile communication technology (3G) and the fourth generation mobile communication technology (4G), have been widely valued and can effectively Expand network coverage and improve network service quality. It is an important means to improve the communication system by installing multiple antennas for users and relays, taking advantage of MIMO diversity and spatial multiplexing to improve system transmission performance. [0003] Many signal processing methods are used in multi-user MIMO relay systems to eliminate the influence of co-channel interference and obtain better transmission efficiency. When using the Zero-Forcing (ZF detection) decod...

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Problems solved by technology

In addition, technical literature Cadambe V R, Jafar S A. "Interference alignment and degrees of freedom of the K-user interference channel," Information Theory, IEEE Transactions on, 54(8):3425-3441, 2008. ("K-user interference Channel Interference Alignment and System Degree of Freedom" IEEE Journal of Information Theory, Vol. 54, No. 8, Page: 3245-3441, 2008), the method of interference alignment in signal processing improves the system degree of freedom, but for each Users can only equip one antenna

Furthermore, Lee, N., J.-B. Lim, and H. Chun, “Degrees of freedom of the MIMO Y channel: Signal space alignment for network coding,” IEEE Trans.Inform.Theory, Vol.56, No. .7, 3332-3342, Jul.2010.("System degrees of freedom for MIMO Y channels: network coding with signal space alignment" IEEE Journal of Information Theory, Vol. 56, No. 7, Pages: 3332-3342, 2010), In this paper, interference alignment is improved and signal space alignment is proposed, which further improves the degree of freedom of the system and is suitable for multi-antenna networks. However, signal space alignment has extremely high restrictions on the number of users and antennas. Involves Physical Layer Security

Furthermore, the technical literature Tao Yang, Xiaojun Yuan, Li Ping, Iain B.Collings and Jinhong Yuan, "A new eigen-direction alignment algorithm for physical-layer network coding in MIMO two-way relay channels", Proceedings of the 2011 IEEE International Symposium on Information Theory-ISIT, p 2253-7, 2011 ("A new network coding scheme based on feature direction alignment under MIMO bidirectional relay channel" IEEE International Conference on Information Theory, 2011) proposed the use of feature direction alignment The signal processing method improves the limitation of the signal space on the number of antennas, but this article is only applicable to two-way relay systems, and cannot be applied to multi-user multi-directional relay channel transmission

[0005] To sum up, the existing technology still has the following deficiencies: (1) In the information transmission of the multi-user MIMO relay system, when the transmission channel correlation is strong, the decoding performance cannot be guaranteed, especially when the relay uses zero-forcing (ZF ) when decoding, if the channel matrix is ​​not ideal, there will be power loss; (2) In the information transmission of the multi-user MIMO relay system, the security of the physical layer is not considered

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