Enhance Wireless Network Performance and Security with Reconfigurable Antennas
Yanjun Pan · UA Campus Repository (The University of Arizona) · 2021
Providing higher throughput, lower latency, and ubiquitous connectivity network services have attracted significant attention in recent years. However, this technology has some inherent limitations that pose significant reliability, throughput, and security challenges to researchers. For example, designing high performance multi-hop wireless networks (MWNs) has remained challenging due to unreliable wireless links, the interference among wireless links, etc. Most existing solutions address these challenges from various layers (e.g., power control, opportunistic routing, and network coding). However, none of them can alter the fundamental characteristics of the physical wireless channel itself, which leads to limited performance gains. On the other hand, the ever-expanding wireless technology is pushing the limit of the network security infrastructure. The broadcast nature of the wireless channel poses numerous security challenges. Traditionally, such challenges are addressed with pre-shared secret keys or out-of-band secure auxiliary channels. However, in many scenarios, these premises may not be satisfied. In contrast, physical (PHY) layer security is a promising means to protect the security of wireless communications under the information-theoretic security notion, without any pre-shared secrets. Hence, PHY-layer security is widely considered as a complement to the conventional cryptography and authentication mechanisms, as it provides an independent layer of protection. However, many practical PHY-layer security schemes have been proven insecure over time. The root of the vulnerability is due to the predictable channel in static indoor environments that allows attackers to manipulate signals and implement advanced attacks (e.g., man-in-the-middle (MitM) attacks). Reconfigurable antennas (RAs) have emerged as a disruptive antenna technology that offers a promising alternative to solve the above challenges at the PHY-layer. RAs can agilely switch among many different antenna states including radiation patterns, so as to suppress interference and maintain high connectivity at the same time. However, so far, the potential of RAs to enhance performance in multi-hop wireless networks has not been explored. Moreover, the state diversity of RAs can be used to enhance PHY-layer security by proactively and dynamically randomizing the physical channel, to create an artificial advantage against the adversary. However, there is a lack of systematic modeling of attacker's behaviors for some strong but practical attacks, and no quantitative security guarantee can be provided. In this dissertation, we focus on alleviating the aforementioned challenges by exploiting the reconfigurability and state diversity of RAs. We start by studying the throughput limit of a given MWN equipped with RAs and formulating a max-flow based optimization framework to derive its throughput bound. We then present the channel randomization primitive to enhance network security based on RAs. First, we present a channel randomization based orthogonal blinding scheme, in which the message confidentiality is protected with the presence of a multi-antenna eavesdropper. Then, we propose a PHY-layer based key generation protocol resistant to the MitM attacker who is capable of injecting her own packets. Finally, the message integrity protection and authentication scheme is designed to defend against adversaries who aim at completely canceling out the received signal at the receiver.