Cooperative transmission method of uplinks of secondary users in cognitive radio system

Abstract

The invention relates to a cooperative transmission method of uplinks of secondary users in a cognitive radio system. The cognitive radio system comprises primary users, secondary users and a base station serving both the primary users and the secondary users. The cooperative transmission method comprises the following steps: selecting cooperative users undergoing cooperative forwarding from idlesecondary users according to the channel information; setting beamforming factors for the selected cooperative users according to the spectrum access mode of a secondary source user; and finding out the normalized eigenvector corresponding to the maximum eigenvalue to serve as the beamforming vector of a receiving array antenna of the base station by decomposing the H2H1PsW (H2H1PsW)H eigenvalue.Compared with the existing technical schemes, the technical scheme adopted by the invention has the following advantages: the cooperative transmission of the uplinks is realized through integration and reutilization of the idle secondary user resources, thus improving the transmission performance; and the scheme is simple and easy to realize and can meet the requirements of the cognitive radio system for high flexibility and instantaneity.

Description

technical field [0001] The invention relates to a cooperative transmission method for an uplink of a cognitive radio system, and belongs to the technical field of wireless communication. Background technique [0002] With the development of wireless communication technology, wireless spectrum resources become more and more scarce and precious. Cognitive Radio technology can allow secondary users (Secondary Users) in the network to dynamically use the idle spectrum of authorized primary users (Primary Users), effectively improve spectrum utilization, and solve the problem of spectrum scarcity. It has become an IMT- One of several breakthrough technologies from Advanced. In the current research on cognitive radio systems, there are mainly two modes of spectrum access for secondary users: the underlay mode and the overlay mode. The overlay mode stipulates that the secondary user can only use this spectrum when the primary user is not using it. The secondary user can negotiate...

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Problems solved by technology

In this scheme, by adjusting the weight value of the antenna beam of the secondary user as the cooperative relay, the secondary user transmitter is assigned an appropriate transmit power, so that the system throughput can be improved, but the method proposed in this paper does not take into account Collaborative user choice problem

In addition, "Beamforming and Power Control for Multi-Antenna Cognitive Two-Way Relaying" published by K.Jitvanichphaibool and other scholars at the 2009 IEEE Wireless Communications and Networking Conference (2009 IEEE Wireless Communications International Conference) Following beamforming and power control in cognitive radio networks), this paper proposes a two-way relay transmission scheme for cognitive networks. The optimal and suboptimal beamforming matrices are obtained through singular value decomposition and search, and optimized The problem is solved to determine the transmission power of each secondary user, but the method proposed in this paper is only for the transmission mode of single-node cooperation, and does not consider the number of cooperative users when multiple cooperative users are selected. In addition, the algorithm proposed in this paper is complex High degree, easy to cause a large delay, which is not conducive to the application of actual scenarios

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