Modeling, Based On Feedback And Ldpc Codes, Eavesdropping Channel

As an advanced communication, the mobile communications plays an important role in people's life, and become more popularity. Such as: ubiquitous mobile communications through e-commerce and e-banking services. The security of wireless channels to mobile communication networks is being more and more concerned and faced more security threats, such as eavesdropping and counterfeiting.The traditional secure communications are not at the physical layer, but through the legitimate communicating parties share a secret key to achieve communication, the characteristic of wireless broadcasting communications and the two sides are not directly connected to the physical of the media, allowing an attacker can easily intercepted information, false information, combined with wireless communication terminals by the physical size constraints, many kinds of encryption communications can not be used, so at the bottom of wireless communication - to solve security problems at the physical layer become necessary.Physical layer information security is a new secure communication hot spots, rising in recent years. The core idea is through the physical layer coding, modulation of the properly to achieve two legitimate sides to achieve reliable communication, while those eavesdroppers cann't get useful information; The physical layer information security not only prevent an attacker from eavesdropping , but also can use the wireless channel characteristics to enable an secret communication system. This paper will focus on the physical layer security technology.As early as 1975, Wyner pointed out: as long as legitimate's channel is better than the eavesdropper's eavesdropping channel, we can build an unconditional security communication between two legitimate sides without sharing any secret key. In the Wyner proposed theory, how to build a wiretap channel even worse channel environment becomes the key of unconditional secrecy communicate.This paper mainly studies the application of channel coding and the channel noise to create a wiretap channel model. Based on different characteristics of channel noise, combined with the feedback and the threshold characteristics of LDPC codes in the BSC and the AWGN channels, and studied the selection of the feedback and channel code overlay of parameters. finally by adding secret codes to complete an unconditional secret communication on the eavesdropping channel, thereby establishing a secret performance of the system carried out numerical simulation .