Secure communications in a multiple input multiple output (MIMO) system in which the eavesdropper's channel is inherently superior to that of the legitimate receiver is described. Both the legitimate receiver and the eavesdropper are assumed to have equal knowledge and comparable computational capabilities and there is no "secret key" known only to the legitimate receiver. The combination of artificial noise added at the transmitter, parallelization of the legitimate channel using the singular value decomposition, and low density parity check (LDPC) codes can overcome the superiority of the eavesdropper's channel and enable secure communications. The effectiveness of the method is greater for larger numbers of antennas and larger modulation constellations.
Secure communications in a multiple input multiple output (MIMO) system in which the eavesdropper's channel is inherently superior to that of the legitimate receiver is described. Both the legitimate receiver and the eavesdropper are assumed to have equal knowledge and comparable computational capabilities and there is no "secret key" known only to the legitimate receiver. The combination of artificial noise added at the transmitter, parallelization of the legitimate channel using the singular value decomposition, and low density parity check (LDPC) codes can overcome the superiority of the eavesdropper's channel and enable secure communications. The effectiveness of the method is greater for larger numbers of antennas and larger modulation constellations.
Recently, MIMO (multiple-input-multiple-output) physical layer secure transmission has attracted great attentions. However, current schemes cannot defend against the passive eavesdroppers with arbitrary number of antennas. To address this problem, in this work, we propose a practical physical layer MIMO secure communication scheme (PLSC) to defend against such an eavesdropper with arbitrary number of antennas. In the proposed scheme, the transmitter first independently generates a random binary sequence as the “key bits (KB)” to “encrypt” (XOR) the confidential information. After that, the transmitter sends the “encrypted information” over the wireless channel, along with mapping key bits to the legitimate receiver simultaneously. The key principle lies in that the KB information is coded in the indexes of the activated/non-activated antennas combination of the legitimate user. Then, the legitimate receiver first observes his/her activated antenna indexes to obtain the corresponding key bits. After that, he/she demodulates the “encrypted information” at the activated antennas, and finally “decrypts” (XOR) the confidential information by using the observed key bits. However, due to the uniqueness and independence of MIMO wireless channel, for any other eavesdroppers who suffer an independent channel from legitimate users, we prove that it cannot observe any information about KB from the received signals, regardless of how many antennas it has used. Consequently, without knowledge of KB, it cannot decrypt any information about the confidential information, too. The reliability and security of PLSC are theoretically demonstrated. The simulation and numerical results fully verified the validity and effectiveness of the proposed scheme.
Physical layer security (PLS) provides strong and lightweight secure communications for vehicle networks, which has attracted great attention. However, current schemes cannot defend against the passive eavesdroppers with any number of antennas. To fill this gap, we propose a physical layer secure MIMO-SVD (singular value decomposition) communication scheme (SSVD) to defend against such an eavesdropper with any number of antennas. In the SSVD scheme, the confidential information first goes through a special data frames secure process at the transmitter. After that, by integrating with SSVD precoding, the key information is attached and delivered in the combination of activated/non-activated MIMO parallel sub-channels of the legitimate receiver through the wireless channel. Due to the uniqueness and independence of wireless channel, only the legitimate receiver can observe the key information and use it to “decrypt” (XOR) the confidential information step by step with an arbitrary low BER (bit error rate). However, for any other eavesdropper who suffers an independent channel from legitimate users, the eavesdropper cannot obtain any key information from the received signals, regardless of how many antennas he/she has. Consequently, the eavesdropper cannot “decrypt” any information about the confidential information. The SSVD security and reliability are theoretically analyzed, and the simulation and numerical results fully verified its validity and effectiveness.
In this article, a secure multiple–input multiple–output (MIMO) wireless communication system is presented and discussed. The proposed system relies on Hamiltonian graphs that are known between the transmitter (Alice) and the legitimate receiver (Bob) and not accessible for any third party intercepter. Lack of knowledge for the proper graph at the eavesdropper (Eve) is shown to substantially degrade the detection capability, where an average bit error rate (ABER) of around 0.5 is reported regardless of the considered signal-to-noise-ratio (SNR) value. The generated graph is used to construct a cycle, where the sequence of data bits to be transmitted at each time instant is converted to a decimal number and the number following this decimal number on the cycle is modulated. As well, Alice transmits a pre designed artificial noise (AN) that is know at Bob but not at Eve to enhance the secrecy rate (SR) of the communication system. It is assumed that Eve is fully aware of the communication protocol and substantial gains in terms of ABER and SR are reported.
This paper studies a secure communication over multiple-input multiple-output multi-antenna eavesdropper (MIMOME) channels which consist of legitimate parities, namely a transmitter and receiver, equipped with multi-antennas and a passive eavesdropper with multi-antennas. For securing the communication between the legitimate parties, we consider an artificial noise (AN) scheme in which the legitimate transmitter sends its secret messages and AN signal together. Meanwhile, it is assumed that the legitimate receiver has a full-duplex capability which enables it to capture the secret message from the transmitter and simultaneously generate a jamming signal to strengthen security. While there have been studies on similar setups, most of them focus on the design of the jamming signal with the assumption of full channel-state information (CSI) and/or system parameter optimization based on numerical evaluations. On the contrary, in this work, we instead introduce a tight lower bound on an achievable ergodic secrecy rate as a versatile analytic tool and derive a closed-form expressions for the bound. To confirm the analytic results, we carry out numerical evaluations of the ergodic secrecy rate which are compared with the proposed lower bound.
This chapter considers securing wireless communications at the physical layer using multiple antennas. In particular, the multiple antenna (MIMO) wiretap channel is presented and its secrecy capacity is provided. Further investigation of the high-SNR characterization of the secrecy capacity, i.e., secure degrees of freedom, reveals that the secrecy capacity of the MIMO wiretap channel does not scale with the transmit power when the eavesdropper has an advantage over the legitimate transmitter in the number of antennas. An external multi-antenna cooperative jammer terminal is introduced to the channel model in order to improve its secrecy capacity scaling with power. The secure degrees of freedom for this new multi-terminal multi-antenna channel is characterized. While for these models the eavesdropper channel state information is known at the legitimate terminals, the chapter next removes this assumption and presents results that utilize multiple antennas in order to provide secure communications irrespective of the eavesdropper channel state. An achievable strong secrecy rate and the secure degrees of freedom characterization for the MIMO wiretap channel when the eavesdropper channel is arbitrary, varying, and unknown at the legitimate terminals are presented. Finally, the extension of this model to the two-user multiple access MIMO wiretap channel is considered and its secure degrees of freedom region is characterized. Introduction The wiretap channel and the notion of secrecy capacity, introduced in [1] and generalized by [2], have provided the framework for physical layer design for wireless channels with information theoretic guarantees against eavesdropping. A natural model in wireless communications is one which utilizes multiple antennas for transmission and reception at each node. The improvement in secrecy rate that can be obtained using multiple antennas in a point-to-point channel with an eavesdropper has been studied extensively in several references, including [3, 4]. Specifically, the secrecy capacity of the Gaussian model consisting of a multiple antenna legitimate transmitter, a multiple antenna legitimate receiver, and a multiple antenna eavesdropper, termed the multiple-input multiple-output (MIMO) wiretap channel, has been identified in full generality in [5, 6].
This paper investigates the power allocation problem for artificial noise (AN) secure precoding systems, and proposes closed-form solutions for maximizing the achievable secrecy rate. It is assumed that the transmitter knows the full channel information at the legitimate receiver, and knows only the statistics of the channel information at the eavesdropper. Lower bounds are derived for the secrecy rates in multiple-input single-output channels with single or multiple eavesdroppers and multiple-input multiple-output channels with multiple eavesdroppers. When the number of transmit antennas is sufficiently large, the bounds are tight, and closed-form solutions can be derived from these bounds. The analytical results suggest simple and yet informative solutions as follows: Let the numbers of receive antennas at the legitimate receiver and at the eavesdropper beNrandNr,e, respectively. The system should distributeNr,e/(Nr+Nr,e)of the power to AN in the high SNR regime, and distribute zero power to AN in the low SNR regime; the rate loss due to the eavesdropper is−Nrlog(Nr/(Nr+Nr,e))−Nr,elog(Nr,e/(Nr+Nr,e))bits/sec/Hz in the high SNR regime and nearly negligible in the low SNR regime. The derived results also show that equal power and water-filling power allocations lead to similar solutions and rate loss. Simulation results corroborate the theoretical results.