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Malicious jamming attacks have been regarded as a serious threat to Internet of Things (IoT) networks, which can significantly degrade the quality of service (QoS) of users. This paper utilizes an intelligent reflecting surface (IRS) to enhance anti-jamming performance due to its capability in reconfiguring the wireless propagation environment via dynamicly adjusting each IRS reflecting elements. To enhance the communication performance against jamming attacks, a robust beamforming optimization problem is formulated in a multiuser IRS-assisted anti-jamming communications scenario with or without imperfect jammer's channel state information (CSI). In addition, we further consider the fact that the jammer's transmit beamforming can not be known at BS. Specifically, with no knowledge of jammers transmit beamforming, the total transmit power minimization problems are formulated subject to the outage probability requirements of legitimate users with the jammer's statistical CSI, and signal-to-interference-plus-noise ratio (SINR) requirements of legitimate users without the jammer's CSI, respectively. By applying the Decomposition-based large deviation inequality (DBLDI), Bernstein-type inequality (BTI), Cauchy-Schwarz inequality, and penalty non-smooth optimization method, we efficiently solve the initial intractable and non-convex problems. Numerical simulations demonstrate that the proposed antijamming approaches achieve superior anti-jamming performance and lower power-consumption compared to the non-IRS scheme and reveal the impact of key parameters on the achievable system performance.

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The interdecadal change of the relationship between the tropical Indian Ocean dipole (IOD) mode and the summer climate anomaly in China is investigated by using monthly precipitation and temperature records at 210 stations in China and the NCEP/NCAR reanalysis data for 1957-2005. The results indicate that along with the interdecadal shift in the large-scale general circulation around the late 1970s, the relationship between the IOD mode and the summer climate anomaly in some regions of China has significantly changed. Before the late 1970s, a developing IOD event is associated with an enhanced East Asian summer monsoon, which tends to decrease summer precipitation and increase summer temperature in South China; while after the late 1970s, it is associated with a weakened East Asian summer monsoon, which tends to increase (decrease) precipitation and decrease (increase) temperature in the south (north) of the Yangtze River. During the next summer, following a positive IOD event, precipitation is increased in most of China before the late 1970s, while it is decreased (increased) south (north) of the Yangtze River after the late 1970s. There is no significant correlation between the IOD and surface air temperature anomaly in most of China in the next summer before the late 1970s; however, the IOD tends to increase the next summer temperature south of the Yellow River after the late 1970s.

The integration of aerial platforms to provide ubiquitous coverage and connectivity for densely deployed terrestrial networks is expected to be a reality in emerging sixth-generation networks. Energy-effificient design and secure transmission are two crucial issues for integrated terrestrial-aerial networks. With this focus, due to the potential of RIS in substantially saving power consumption and boosting the security of private information by enabling a smart radio environment, this paper investigates the energy-efficient hybrid beamforming for multilayer reconfigurable intelligent surface (RIS)-assisted secure integrated terrestrial-aerial network for defending against simultaneous jamming and eavesdropping attacks. Specifically, with the available of angular information based imperfect channel state information (CSI), we propose a framework for the joint optimization of user's received precoder, terrestrial BS's and HAP's digital precoder, and multi-layer RIS analog precoder to maximize the system energy efficiency (EE) performance. For the design of received precoder, a heuristic beamforming scheme is proposed to convert the worst-case problem into a min-max one such that a closed-form solution is derived. For the design of digital precoder, we propose an iterative sequential convex approximation approach via capitalizing the auxiliary variables and first-order Taylor series expansion. Finally, a monotonic vertex-update algorithm with penalty convex concave procedure is proposed to obtain analog precoder with low computational complexity. Numerical results show the superiority and effectiveness of proposed optimization framework and architecture.