基于扩维域能量弥散的隐蔽通信

Covert communications based on energy dispersion in extended dimensions

无线通信技术是现今蓬勃发展的数据时代不可或缺的重要信息传输手段之一,而无线数据的安全性更是构建数据时代的磐石.在某些特殊应用场景中,发送方不但要保障信息内容的安全,甚至要做到无线信号传输的行为不被侦收发现.面对严峻的无线电侦收威胁,传统的隐蔽通信手段是基于某一个或两个维域进行能量弥散以降低被侦测概率,如基于扩频的码分多址接入技术将能量弥散到频域,短时猝发技术将能量弥散在时域的多个离散时段,短时猝发与跳频结合的技术将能量弥散在时、频两域.本文首先回归无线传输过程中信号能量弥散的物理本质,将隐蔽通信模型从能量在单维域弥散扩展至时–频–空的多维域能量弥散.即利用此模型并借助无线电传播理论以及数字信号处理方法等工具对无线信号能量在时–频–空3个维域的能量弥散进行建模,设计了侦听方面向时–频–空维域的能量检测器.接下来,在此多维域能量检测模型下,推导了侦听方收集能量的表达式,侦听方使用平均噪声能量作为门限的检测概率上下边界表达式,以及在纽曼–皮尔逊(Neyman-Pearson)能量检测器下的检测概率上下边界表达式.然后,结合理论推导分析、归纳并证明了扩维域能量弥散以实现隐蔽通信思路的正确性.然后,结合仿真结果,从博弈的角度讨论了在多维域能量检测模型下发送方隐蔽性存在的条件以及侦听方接收机的改进策略.最后,针对实际工程,揭示了无线隐蔽通信系统隐蔽性与可靠性这一内生矛盾及相互作用机理,进而给出了实现无线隐蔽传输的原理及技术途径.

Wireless communication technology is an indispensable means of information transmission in the thriving data era,while wireless security is particularly crucial in establishing the foundation of this era.In certain specific scenarios,the transmitter must not only ensure the security of the information content but also aim to achieve the transmission behavior of wireless signals without being detected by eavesdroppers.In response to the serious threat of radio eavesdropping,traditional covert communication methods depend on dispersing energy in one or two domains to minimize the probability of detection.For example,the code division multiple access technology based on the spread spectrum disperses energy in the frequency domain.Burst transmission technology disperses energy in discrete time intervals in the time domain while combining burst transmission with frequency hopping disperses energy in both time and frequency domains.The paper initially backtracks the physical nature of energy dispersion in wireless signal transmission.The covert communication model has been expanded from a single-domain energy dispersion to a multi-domain approach,encompassing the time,frequency,and space domains.By employing this model and tools such as radio propagation and digital signal processing theory,the paper models the energy dispersion of wireless signals in the three domains of time,frequency,and space.An energy detector is designed for eavesdropping in the three domains of time,frequency,and space.Subsequently,the expressions for capturing energy by the eavesdropper are derived using the multi-domain detection model.The expressions for the upper and lower boundaries of the eavesdropper's detection probability using average noise energy as the threshold,as well as those for the upper and lower boundaries of the detection probability under the Neyman-Pearson energy detector,are also derived.Subsequently,combining theoretical derivation and analysis,we deduce and prove the guiding principles of multi-domain energy dispersion-based covert communication.Subsequently,the paper explores simulations and discussions,from a game-theoretic perspective,of the conditions for the covert presence of the transmitter under the multi-domain energy detection model and the strategies for improving the eavesdropper's capabilities.Finally,the inherent contradiction and interaction mechanism between the covertness and reliability of wireless covert communications are revealed for practical design and realization.Then,the principle and technical approach to achieving wireless covert transmission are provided.