Hu Hequn, Gao Zhenzhen, Liao Xuewen, Leung Victor C M
School of Electronic and Information Engineering, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an 710049, China.
Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC V6T1Z4, Canada.
Sensors (Basel). 2017 Sep 4;17(9):2023. doi: 10.3390/s17092023.
The Internet of Things (IoT) represents a bright prospect that a variety of common appliances can connect to one another, as well as with the rest of the Internet, to vastly improve our lives. Unique communication and security challenges have been brought out by the limited hardware, low-complexity, and severe energy constraints of IoT devices. In addition, a severe spectrum scarcity problem has also been stimulated by the use of a large number of IoT devices. In this paper, cognitive IoT (CIoT) is considered where an IoT network works as the secondary system using underlay spectrum sharing. A wireless energy harvesting (EH) node is used as a relay to improve the coverage of an IoT device. However, the relay could be a potential eavesdropper to intercept the IoT device's messages. This paper considers the problem of secure communication between the IoT device (e.g., sensor) and a destination (e.g., controller) via the wireless EH untrusted relay. Since the destination can be equipped with adequate energy supply, secure schemes based on destination-aided jamming are proposed based on power splitting (PS) and time splitting (TS) policies, called intuitive secure schemes based on PS (Int-PS), precoded secure scheme based on PS (Pre-PS), intuitive secure scheme based on TS (Int-TS) and precoded secure scheme based on TS (Pre-TS), respectively. The secure performances of the proposed schemes are evaluated through the metric of probability of successfully secure transmission ( P S S T ), which represents the probability that the interference constraint of the primary user is satisfied and the secrecy rate is positive. P S S T is analyzed for the proposed secure schemes, and the closed form expressions of P S S T for Pre-PS and Pre-TS are derived and validated through simulation results. Numerical results show that the precoded secure schemes have better P S S T than the intuitive secure schemes under similar power consumption. When the secure schemes based on PS and TS polices have similar P S S T , the average transmit power consumption of the secure scheme based on TS is lower. The influences of power splitting and time slitting ratios are also discussed through simulations.
物联网（IoT）展现出一个光明的前景，即各种普通电器能够相互连接，并且与互联网的其他部分相连，从而极大地改善我们的生活。物联网设备的硬件受限、复杂度低以及能源约束严峻，带来了独特的通信和安全挑战。此外，大量物联网设备的使用还引发了严重的频谱稀缺问题。在本文中，考虑认知物联网（CIoT），其中物联网网络作为使用底层频谱共享的次级系统。一个无线能量收集（EH）节点被用作中继来提高物联网设备的覆盖范围。然而，该中继可能是一个潜在的窃听者，会拦截物联网设备的消息。本文考虑通过无线能量收集不可信中继实现物联网设备（如传感器）与目的地（如控制器）之间安全通信的问题。由于目的地可以配备充足的能量供应，基于功率分割（PS）和时间分割（TS）策略提出了基于目的地辅助干扰的安全方案，分别称为基于PS的直观安全方案（Int-PS）、基于PS的预编码安全方案（Pre-PS）、基于TS的直观安全方案（Int-TS）和基于TS的预编码安全方案（Pre-TS）。通过成功安全传输概率（P_SST）这一指标评估所提方案的安全性能，P_SST表示主用户的干扰约束得到满足且保密率为正的概率。对所提安全方案的P_SST进行了分析，推导了Pre-PS和Pre-TS的P_SST的闭式表达式，并通过仿真结果进行了验证。数值结果表明，在相似功耗下，预编码安全方案的P_SST优于直观安全方案。当基于PS和TS策略的安全方案具有相似的P_SST时，基于TS的安全方案的平均发射功耗更低。还通过仿真讨论了功率分割和时间分割比率的影响。
