Image encryption (IE) technology is vital to privacy, but the parameter range of the traditional image encryption technology is limited. So it is important to enhance the performance of IE methods. In this study, a plaintext associative IE based on the improved logistic map and hyperchaotic system is proposed. The improved logistic map scrambles the pixels of the image. Then the hyperchaotic system performs diffusion and confusion operations on the image. For parameters μ and r, the sequence generated by the improved logistic map can traverse and uniformly distribute in the space (0,1). The Lyapunov exponent of the improved logistic map is greater than 21.5. The correlation coefficients of the encrypted image pixels after encryption are all less than 0.05. The UACI and NPCR indices of the improved encryption method are close to their theoretical values of 98.6133 and 33.1287, respectively, which are higher than those of the reference methods. The improved encryption method overcomes the limitations in the parameter range of traditional image and text encryption techniques, slow encryption speed, and uneven chaotic sequences. This method has higher security and sensitivity, andit can be used to establish a plaintext associative IE method.
Over the last couple of decades the world has witnessed gradual, yet steady evolution of mobile wireless communications towards second, third and fourth generation wireless networks. Introduction of digital modulations, effective frequency reuse, penetration of packetbased Internet and rapid advancement in physical layer technologies. Currently all IP based 4G Long Term Evolution (LTE/4G) networks have become a part of everyday life. As a result, a set of new, user-oriented mobile multimedia applications, like mobile video conferencing, streaming video, e-healthcare and online gaming are coming up. These new applications are not only satisfying users’ requirements, but also opening up new business horizons for wireless operators to increase their revenue. Fifth generation mobile communications (5G) are expected to accommodate rapidly increasing mobile traffic aiming at the realization of a “Hyper Connected World” in which all people and surrounding things are connected and information is exchanged between them, and to play the role of a basis of the Internet of everything. The 5G wireless network is expected to become a “Heterogeneous Network” where new wireless access technologies incompatible with 4G and the wireless access technologies for unlicensed band are incorporated with the enhanced technology of 4G (e.g. IMT-advanced). This paper introduces the vision and emerging technology trends of 5G, shows key directions of the research challenges and development of 5G in the future.
<p>With the rapid development of wireless network communication in China, information transmission technology has become the key point. Information transmission mainly includes wireline network communication, wireless network communication and broadband communication. Due to the limitation of communication barriers in different areas and environment, problems, such as poor signal, weak channel transmission and distribution ability, and channel congestion, will emerge during the information transmission process. Therefore, by taking transmission control technology as the research object, analysis on the disadvantages of computer wireless network communication are conducted in this article. Some corresponding improvement measures are also put forward for reference.</p>
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