This paper proposes new approaches to enhance the security of wireless sensor networks. Two randomized array transmission schemes are developed to secure wireless sensor networks at the physical layer. Transmission secrecy can be guaranteed by either the inherent ambiguities of MIMO blind equalization or the intentionally created ambiguities. Perfect secrecy is shown to be realizable under certain conditions. The schemes do not require secret keys, and work under more relaxed assumptions than existing techniques. They are useful for secure wireless data transmission or key distribution in wireless sensor networks.
This paper proposes new approaches to enhance the security of wireless sensor networks. Two randomized array transmission schemes are developed to secure wireless sensor networks at the physical layer. Transmission secrecy can be guaranteed by either the inherent ambiguities of MIMO blind equalization or the intentionally created ambiguities. Perfect secrecy is shown to be realizable under certain conditions. The schemes do not require secret keys, and work under more relaxed assumptions than existing techniques. They are useful for secure wireless data transmission or key distribution in wireless sensor networks.
The applications of Wireless Sensor Networks (WSNs) are widespread in areas such as environmental monitoring, industrial automation, healthcare and smart infrastructures, where secure and reliable wireless communication is essential. The nature of a wireless channel, however, lends itself to the problem of eavesdropper-directed wireless sensor networking, interception and unauthorized access. This paper presents a secure physical layer communication system featuring the combination of channel estimator, physical layer key generator, artificial noise generator and adaptive power allocator to increase the confidentiality of physical layer communications and simultaneously achieve energy efficiency. A hybrid security mechanism is used, which takes advantage of the channel characteristics to create secret keys and to make the eavesdropper's signal reception worse by introducing controlled artificial noise. Key performance parameters considered for simulation-based evaluation are secrecy capacity, BER, PDR, Throughput, Energy consumption and Network lifetime. Results show that the secrecy capacity is 6.3 bps/Hz, the packet delivery ratio is 98.7%, the bit error rate is 10⁻⁶, and the network lifetime is 1675 rounds. The proposed framework is much more effective in terms of both communication security and energy efficiency than the traditional WSNs security schemes.
Information-theoretic secrecy gives the strongest information security that is important for military wireless networks. In this paper, we show that randomized MIMO transmissions can achieve such secrecy. A method is proposed to randomize the MIMO transmission coefficients. The received signal of the adversary has some special statistical distributions, based on which the indeterminacy of the adversary's blind deconvolution is proved. Receiving error rates and secret channel capacity are analyzed and simulated. This paper points out a practical way to realize the well-known wire-tap channel for perfect secrecy, which is one of the interesting challenges in information theory. The proposed method is also useful for key management in military wireless networks.
In contrast to the pessimistic view on perfect secrecy, studies on information-theoretic secrecy have shown that perfect secrecy may be possible in practice. A typical example is the Wyner’s wire-tap channel concept. However, existing approaches mostly depend on unrealistic noise or error-rate assumptions. We propose a more practical way in this paper which uses advanced space-time transmissions for enhanced information-theoretical secrecy. Based on the fundamental limits of MIMO blind channel identification, space-time transmissions with proper randomization can effectively prevent the adversary from channel estimation while allowing reliable transmission between the authorized parties. The high error rate suffered by the adversary enhances secret channel capacity. This paper points out a new and practical approach for secret-key agreement which achieves perfect secrecy based on the physical-layer signal processing techniques.
An important building block of the cross-layer network security design is the physical-layer security which addresses problems such as whether the physical-layer can have build-in security and whether physical-layer techniques can assist the upper-layer encryption-based security techniques. This paper provides a positive answer by realizing information-theoretic secrecy with space-time transmissions. While most existing results on information-theoretic secrecy rely on some impractical assumptions, we propose a more practical approach that uses the redundancy of space-time transmissions to create intentional ambiguity to the adversary. Secrecy can be guaranteed even if the adversary has extremely high receiving signal-to-noise ratio. This approach is presented as a new way for secret-key agreement. Simulations in terms of receiving error rate and secret channel capacity are presented.
The current research on physical layer security is far from implementations in practical networks, arguably due to impractical assumptions in the literature and the limited applicability of physical layer security. Aiming to reduce the gap between theory and practice, this thesis focuses on wireless physical layer security towards practical assumptions and requirements. In the first half of the thesis, we reduce the dependence of physical layer security on impractical assumptions. The secrecy enhancements and analysis based on impractical assumptions cannot lead to any true guarantee of secrecy in practical networks. The current study of physical layer security was often based on the idealized assumption of perfect channel knowledge on both legitimate users and eavesdroppers. We study the impact of channel estimation errors on secure transmission designs. We investigate the practical scenarios where both the transmitter and the receiver have imperfect channel state information (CSI). Our results show how the optimal transmission design and the achievable throughput vary with the amount of knowledge on the eavesdropper's channel. Apart from the assumption of perfect CSI, the analysis of physical layer security often ideally assumed the number of eavesdropper antennas to be known. We develop an innovative approach to study secure communication systems without knowing the number of eavesdropper antennas by introducing the concept of spatial constraint into physical layer security. That is, the eavesdropper is assumed to have a limited spatial region to place (possibly an infinite number of) antennas. We show that a non-zero secrecy rate is achievable with the help of a friendly jammer, even if the eavesdropper places an infinite number of antennas in its spatial region. In the second half of the thesis, we improve the applicability of physical layer security. The current physical layer security techniques to achieve confidential broadcasting were limited to application in single-cell systems. The primary challenge to achieve confidential broadcasting in the multi-cell network is to deal with not only the inter-cell but also the intra-cell information leakage and interference. To tackle this challenge, we design linear precoders performing confidential broadcasting in multi-cell networks. We optimize the precoder designs to maximize the secrecy sum rate with based on the large-system analysis. Finally, we improve the applicability of physical layer security from a fundamental aspect. The analysis of physical layer security based on the existing secrecy metric was often not applicable in practical networks. We propose new metrics for evaluating the secrecy of transmissions over fading channels to address the practical limitations of using existing secrecy metrics for such evaluations. The first metric establishes a link between the concept of secrecy outage and the eavesdropper's ability to decode confidential messages. The second metric provides an error-probability-based secrecy metric which is often used for the practical implementation of secure wireless systems. The third metric characterizes how much or how fast the confidential information is leaked to the eavesdropper. We show that the proposed secrecy metrics enable one to appropriately design secure communication systems with different views on how secrecy is measured.
Physical layer security has been widely read up for decades to use physical layer qualities like unconventionality in wireless channels, motion toward clamor ratio hole, conscious sticking, and so on, to secure wireless correspondences. Secret rate is essential to define secure communication transmission rate in the presence of an eavesdropper. WSNs need secure communications since sensors send data to a fusion center. The most common cryptography techniques have been considered, but most of them are too computationally and energy-intensive for WSNs. Digital telecommunications networks sharing resources are called data networks. There are two networks: wired and wireless. Wireless networks are very popular due to its wireless setup and many household, business, and telecommunications networking applications. WSN were created when sensors detected physical or environmental conditions like pressure, temperature, or beam. WSN are elastic, easy, and straightforward. They grow because they're cheap and efficient. Wireless Sensor Networks have multiple sensor nodes scattered across a field that can measure, sense, compute, communicate, and send results to a base station. With increasing competence, security is also improving. Though the network was designed to be safe, hackers and attackers always find a way in and attack.