Cognitive radio network (CRN) and non-orthogonal multiple-access (NOMA) play the crucial roles in the fifth generation wireless communication systems. However, the physical-layer security still ...remains quite challenging. In this letter, a downlink cascaded transmitting zero-forcing-beamforming (ZFBF) technique is proposed to secure communications in a two-cell multiple-input multiple-output (MIMO) NOMA-based CRN. The proposed technique protects the information from illegitimate users (eavesdroppers) within the same and adjacent cells. The restriction on the number of at the transmitter can also be relaxed by applying the signal alignment for the ZFBF technique. This proposed new method can maximize the total secrecy rate of the MIMO-NOMA-based CRNs in the lack of conventional transceiver beamforming techniques. Numerical and simulation evaluations have demonstrated the effectiveness of the proposed method.
In this paper we address physical layer security of multiple input multiple output (MIMO) communication system in presence of multiple destinations and passive eavesdroppers. Since the eavesdroppers ...are passive, it is assumed that channel state information (CSI) of the eavesdroppers are not available at the source. Spatial beamforming and artificial noise broadcasting are chosen as the strategy for securing the transmission. Secrecy capacity for optimum power allocation and uniform power allocation with power constraints are analyzed. Optimum power allocation technique is applied when all the authorized users have different data rates. Uniform power allocation is done when all the authorized users have the same data rate. The analytical results are derived and validated through simulation results and finally it is compared with existing methods.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The physical layer security (PLS) has become crucial in the fifth generation (5G) wireless technology where non-orthogonal multiple-access (NOMA) plays an essential role for sharing the spectrum ...among multiple users. Multiple-input multiple-output (MIMO)-NOMA based cognitive radio network (CRN) enhances the spectral-efficiency at the cost of PLS. In this paper, a transmit-zero-forcing beamforming (ZFBF) technique with signal alignment is proposed to improve the PLS for MIMO-NOMA based CRN when perfect channel state information (CSI) is available at the base station (BS). In this study, a generalized cellular model with multi-cell is considered where each cluster is formed with a primary user (PU) and a secondary user (SU) to adopt the CRN. The locations of PU and SU are kept arbitrary within the cells. We also propose an eigen beamforming technique to improve the PLS for MIMO-NOMA based CRN when the imperfect CSI is available at the BS. For both beamforming techniques, optimum power allocation algorithms are developed for further enhancement of the PLS. Finally, a closed-form expression of the secrecy outage probability for the Nakagami-<inline-formula><tex-math notation="LaTeX">m</tex-math></inline-formula> fading channels is derived and compared with simulation results and other existing techniques.
This paper presents the optimal physical-layer security scheme of both primary user (PU) and secondary user (SU) in the underlay multiple-input multiple-output cognitive-radio network (MIMO-CRN) by ...use of a bi-directional zero-forcing beamformer. The proposed new method enables the PU to communicate along with the SUs through a relay node without sacrificing their individual secrecy capacity, i.e., without causing interference to each other even in the presence of eavesdropper(s). In the first phase, a transmitting beamformer at the PU/SU transmitters and a receiving beamformer at the relay have been adopted to separate PU and SU data. In the second phase, a bi-directional beamformer has been applied to eradicate the necessity of involving artificial noise for preventing the active eavesdropper(s). To maximize the total secrecy capacity, a generalized non-linear optimization problem has been formulated and converted to a simplified constrained optimization problem by utilizing the beamformer and the associated subspace restriction. Then, this problem is solved by the Lagrangian method. Both theoretical and numerical analyses of the total and individual ergodic secrecy rates are provided to demonstrate the effectiveness of our proposed method. The secrecy outage probability is also derived to evaluate the performance variations of our proposed scheme when the channel-estimation error occurs.
Recently, combination of full-duplex (FD) technology with existing wireless devices are gaining much interest due to their spectrum efficient usage. In this work, a cognitive radio network (CRN) with ...FD relay for secondary user (SU) is proposed and physical layer security (PLS) issue is analyzed in the presence of passive eavesdropper by using maximum ratio transmission (MRT) and zero forcing beamforming (ZFBF) techniques. The restriction of self interference at FD relay is cancelled by using ZFBF technique when the number of transmit antenna at relay is greater than the number of receive antenna; on the other hand, null space projection (NSP) is applied for the reverse scenario. For information sharing, both ZFBF and MRT techniques are used. The FD relay is used for generating artificial noise (AN) to degrade the received signal-to-noise ratio (SNR) of the eavesdroppers while simultaneously receive data from secondary transmitter. The ergodic physical layer secrecy capacity and physical layer secrecy outage of both primary user (PU) and SU are evaluated. Finally, Monte-Carlo simulation is performed to compare the proposed approach with other existing techniques.
This paper presents the optimal physical-layer security scheme of both primary user (PU) and secondary user (SU) in the underlay multiple-input multiple-output cognitiveradio network (MIMO-CRN) by ...using bi-directional zero-forcing beamforming technique. The proposed method enables the PU to communicate along with the SU without sacrificing their individual secrecy capacity, i.e., without causing interference to each other in the presence of eavesdropper(s). In this method, a bi-directional beamforming has been applied to eradicate the necessity of involving artificial noise for preventing the active eavesdropper(s). Both theoretical and numerical analyses of the secrecy outage probability are provided to demonstrate the effectiveness of our proposed method. The secrecy outage probability is also derived to evaluate the performance variations of our proposed scheme when the channel-estimation error occurs.
Multiple Access Interference (MAI) is a serious source of noise in Optical Code Division Multiple Access (OCDMA) system. In this perspective, a new technique has been proposed in this paper to reduce ...the effect of MAI in OCDMA receiver. The effect of interference arising from other user code to the intended user has been reduced by subtracting the interference (multiplied by a factor) from the received signal. It has been observed that the distance between different codes influences the value of MAI on the intended user. Hence a new technique has been proposed to optimize the hardware requirement and complexity of the receiver for reducing MAI. The structure has been implemented using Advanced Binary Optical Logic Gates (ABLOGs) leading to reduction of optical-electrical conversion time. Simulations have been carried out using MATLAB to obtain the variation of error probability with number of users for different iterations. Thus, the effectiveness of the proposed technique has been established in terms of the improvement in the Bit Error Rate (BER). It has also been established that this new method gives better result in first iteration leading to faster simulation time.
Performance analysis of sidelobe cancellation method has been carried out in this paper. Binary offset carrier (BOC) modulation, which is an advanced modulation technique, is used in modern global ...navigation satellite systems (GNSS). Acquisition of BOC (m,n) modulated signal is an important activity and Sidelobe cancellation method (SCM) is one of the generic methods used for unambiguous acquisition of BOC(m,n) modulated signals. This paper infers that relationship between different values of m and n has an impact on the overall performance of SCM for detection of unambiguous BOC (m,n) signal after detailed simulation with and without noise.
Automatic Speaker Verification (ASV) is a challenging task over the mobile/IP based system as the coding introduces some loss in system performance. This paper reports on the work in progress to ...examine the impact of GSM-AMR codec used in mobile at its various bit rates and G.729 codec for VoIP, along with different kind of noise and packet loss scenario for the speech signal. PURE YOHO database has been used for the evaluation of this task. Respective encoder and decoders are used back to back on wideband clean microphone speech to simulate the real-life situation. Evaluation of performance is done through the measurement of Equal Error Rate (EER). It has been shown that the loss due to GSM-AMR codec is very significant for speaker verification compared to undecoded speech. Though the packet loss and bit rate may degrade the quality of speech but it is not significant to detection of speaker's identity.
