Physical layer secure transmission method in OFDM (orthogonal frequency division multiplexing) amplify-and-forward relay system

Abstract

The invention discloses a physical layer secure transmission method in an OFDM (orthogonal frequency division multiplexing) amplify-and-forward relay system. According to the invention, an amplify-and-forward protocol is adopted in relaying, equivalent channels of all links between a source node and a destination node are estimated at first, and then artificial noises are designed into a null space of a physical channel of a source node-relay-destination node link, so that the artificial noises impose no interference on the destination node. The security rate is maximized under a condition that the source node and a relay node are restricted in power. The optimization problem is non-convex, so slack variable substitution and an ICA technology are adopted to convert the original non-convex problem into a series of nearly convex problems, and thus the problems can be solved by using a CVX tool. A simulation result shows that, the method disclosed by the invention can acquire a good security rate and stable performance. Compared with a destination node cooperative interference method and a noise-free method, the method disclosed by the invention not only can acquire stable and effective security, but also can avoid influences brought about by the position of an eavesdropping node.

Description

technical field [0001] The invention belongs to the technical field of physical layer security of a wireless relay system, and in particular relates to a time-domain noise design method for resisting eavesdropping by an external eavesdropping node in an OFDM amplifying and forwarding (AF) relay system. Background technique [0002] As a key technology in 4G, Orthogonal Frequency Division Multiplexing (OFDM) technology has many advantages such as anti-multipath fading, high spectrum efficiency, and flexible spectrum resource allocation, which solves people's current needs for high-speed communication. In the construction of 4G system, in order to make the system have higher coverage and lower construction cost, people introduce relay technology into 4G system. The relay technology enhances the coverage and service quality of wireless communication, and reduces the construction cost. The combination of OFDM technology and relay technology realizes high-speed data transmission...

AI Technical Summary

Problems solved by technology

According to the survey, there is no research and discussion on the addition of time-domain artificial noise to interfere with eavesdroppers in the OFDM amplified relay system.

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