Hybrid MIMO and Phased-Array Directional Modulation for Physical Layer Security in mmWave Wireless Communications

Multiple input multiple output (MIMO) technology has evolved over the past few years into a technology with great potential to drive the direction of future wireless communications. MIMO technology has become a solid reality when massive MIMO systems (MIMO with large number of antennas and transceivers) were commercially deployed in several countries across the world in the recent past. Moreover, MIMO has been integrated into state-of-the-art paradigms such as fifth-generation (5G) networks as one of the main enabling technologies. MIMO possesses many attractive and highly desirable properties such as spatial multiplexing, diversity gains, and adaptive beamforming gains that leads to high data rates, enhanced reliability, and other enhancements. Nevertheless, beyond 5G technologies demand wireless communication systems with, among other properties, immensely higher data rates and better reliability simultaneously at the same time. In this work, a new, novel MIMO technique for simultaneously achieving multiplexing and diversity gains as well as completely eliminating any processing at the MIMO receiver, leading to advantages such as low complexity and low power consumption, is proposed. The proposed technique employs the design of interference-canceling matrices, which are calculated from the channels between the transceiver antennas, where the matrices are employed at the base station to help achieve multiplexing and diversity gains simultaneously. The novelty and efficiency of the introduced paradigm is demonstrated via mathematical models and validated by Monte Carlo simulations. Results indicate that the proposed system outperforms conventional MIMO models.

Hybrid precoding design for secure smart-grid enabled MIMO wireless communications in Industry 5.0

Multiple MIMO (Multiple Input Multiple Output) modes are the salient characteristics of 802.11n wireless networks. An efficient MIMO mode switching scheme is highly desirable for rate adaptation, which can optimize combination of MIMO mode and MCS (Modulation Coding Scheme) to achieve the maximum system throughput. In this paper, we have proposed and verified three design guidelines for the MIMO mode switching through real experiments. Based on these guidelines, we then present a simple and efficient MImo mode Switching Scheme, called MISS, and implement it into the Atheros-based device driver. MISS uses a crossover step-based searching algorithm to find the appropriate MIMO mode for rate adaptation. The efficiency of MISS has been evaluated through real experiments conducted in the indoor environments.

Physical layer security (PLS) in wireless communication systems has attracted extensive research attentions in recent years. Unlike cryptography-based methods applied in upper-layer in network, PLS methods are applied in physical layers and can provide information-theoretic security by utilizing the randomness of signals and wireless channels. In this survey, we provide a comprehensive review in the domain of physical layer authentication (PLA) in wireless communication systems, including the concepts, several key techniques of typical PLA architectures as well as future challenges and research trends in more sophisticated communication systems. The survey begins with an overview of the background and basic concepts of PLA, such as the general model of wireless security communication system, typical frameworks of key-based/less PLA systems, and the common attack models. We then discuss the major concerns and key techniques that are applied in PLA systems, where three types of authentication schemes are considered, i.e., the authentication based on channel information, radio-frequency and identity watermarks. Basic models and representative research results about key approaches and techniques applied to the authentication systems above are subsequently covered. Finally, the associated challenges and potential research trends of PLA in future communication systems are presented at the end of the survey paper.

As per the conception of RF (Radio) propagation, wireless communications can be easily overheard by unauthorized users for interception and thus wireless communication are highly vulnerable to eaves dropping attacks by exploitation of physical characteristics of wireless channels. The propose work is focused on development of diversity techniques to enhance physical layer security, marking a paradigm Shift from conventional artificial noise generation and beam forming techniques. Artificial noise techniques are highly power hungry and require on additional degree of power capacity which is not suitable for better operated system. Thus work is focused at development of a new techniques using variable length cryptography in which MAC (Medium Access Control)/ address of the wireless nodes for key generation purposes. Also, it is proposed, that the keys for communication encryption are randomized by a global time source such as GPS or internal master RTC (Real Time Clock). This unique feature allows a high degree of security as keys are truly random due to Millisecond level synchronization key randomization using a global accurate time source facility highly secure communication in a closed group. Also, the author has proposed key expiry time, after elapse station of such time, all key will have to be farce fully regenerated.

Orthogonal frequency division multiplexing (OFDM) offers a promising solution for emerging high-data-rate services. Moreover, physical layer security was proposed as an alternative way to provide information security in wireless communications. In this work, we focus on improving physical layer security in OFDM systems. Our approach perturbs the effective channels observed at eavesdroppers by nonlinear distortion, while maintaining the same effective channel experienced at the intended receiver. At the transmitter, the perturbation on eavesdropper's effective channel is random and can be changed on a symbol-by-symbol basis based on the known original channel state information (CSI). At the intended receiver, no additional information or information exchange with the transmitter is required for data detection. We derive the results of the proposed scheme for the multiple-input single-output single-antenna-eavesdropper (MISOSE) wiretap channel. According to simulations, the proposed scheme can severely degrade the receiving performance at eavesdroppers and outperform the artificial-noise-based approaches in the performance measure of BER.

Internet of Things (IoT) is becoming an emerging paradigm to provide pervasive connectivity where “anything“ can be connected “anywhere” at “anytime” via massive deployment of physical objects like sensors, controllers, and actuators. However, the open nature of wireless communications and the energy constraint of the IoT devices impose strong security concerns. In this context, traditional cryptographic techniques may not be suitable in such a resource-constrained network. To address this problem, an effective security solution that ensures a trade-off between security effectiveness and energy efficiency is required. In this paper, we exploit cooperative transmission between sensor nodes in IoT for e-Health application, as a promising technique to enhance the physical layer security of wireless communications in terms of secrecy capacity while considering the resource-impoverished devices. Specifically, we propose a dynamic and cooperative virtual multiple-input and multiple-output (MIMO) configuration approach based on game theory to preserve the confidentiality of the transmitted messages with high energy savings. For this purpose, we model the physical layer security cooperation problem as a non-transferable coalition formation game. The set of cooperative devices form a virtual dynamically-configured MIMO network that is able to securely and efficiently transmit data to the destination. Simulation results show that the proposed game-based virtual MIMO configuration approach can improve the average secrecy capacity per device as well as the network lifetime compared to non-cooperative transmission.

In this article, the physical layer security (PLS) is investigated for reconfigurable intelligent surface (RIS)-aided wireless communication systems, where one RIS is deployed to assist the communications between a pair of transmitter (Alice) and receiver (Bob), under a passive eavesdropper (Eve) attack. For the Eve, different from the bounded channel state information uncertainty model, the distribution of the Eve's location is introduced into the wiretap link. In the proposed system, considering that the Eve can overhear signals transmitted from Alice or reflected by the RIS, two scenarios are studied for RIS-aided secure communication systems: one is that the Eve distributes close to Alice without the RIS orientation, and the other is that the Eve locates close to Bob and in the presence of the RIS. After investigating the probability distribution functions of the Eve's location and the wiretap link, the novel cumulative density functions (CDFs) of the received signal-to-noise ratios (SNRs) at the Eves are, respectively, derived for the two considered scenarios, taking into account the effects of RIS reflection coefficients, pathloss, and Eve's location distribution. The closed-form expressions for the probability of the nonzero secrecy capacity and the ergodic secrecy capacity are obtained, providing insights into the impact of the Eve's location uncertainty and the RIS design on the secrecy performance. Moreover, based on the derived CDFs for received SNRs at Eves, the secrecy outage probabilities are, respectively, analyzed. Specifically, under the constraint of the secrecy outage probability, the closed forms of the minimum required SNRs at Bob and the number of RIS elements are also obtained. Simulation and analytical results corroborate the derived expressions and reveal the tradeoff between the system's energy efficiency and the number of RIS elements.

This paper present the review on the wireless system specifically with Multiple Input Multiple Output (MIMO) technique. This is due to the advantage of MIMO system that able to enhanced the overall wireless channel capacity. Besides system performances, the size and mobility of the communication devices are also contributed the successfulness of proposed wireless communication system. The compact antenna design has been discussed by many researchers for various application. However, the needs of compact antenna with capability of multiple application is very significant in wireless communication today. Therefore, this paper will review the compact antenna design for wireless MIMO application based on slot design methods.

Nowadays, security in wireless communication is in high demand. The communication of messages or data should be secure, and various security technologies are used to achieve this. Although there are many advanced cryptographic approaches for securing confidential information, they have one disadvantage: high complexity and computational requirements. To address this drawback, physical layer security has been introduced into wireless networks. This paper provides a brief analysis of various approaches to security (physical security). Two main factors are identified: secrecy rate and security design through optimization. Security design depends on the selection of antennas and nodes, beamforming, and the distance between the source and destination. Based on these factors, optimization approaches for security design are discussed. Four main types of optimization problems are identified: Maximizing the secrecy rate, Minimizing secrecy outage probability, Reducing power consumption, Maximizing secure energy efficiency. The best method to maximize the secrecy rate is cooperative schemes. In the cooperative approach, a relay node is used to enhance security between the source and destination by introducing a noise signal.

Directional modulation (DM), as an emerging promising physical layer security (PLS) technique at the transmitter side with the help of an antenna array, has developed rapidly over decades. In this study, a DM technique using a polarization sensitive array (PSA) to produce the modulation with different polarization states (PSs) at different directions is investigated. A PSA, as a vector sensor, can be employed for more effective DM for an additional degree of freedom (DOF) provided in the polarization domain. The polarization information can be exploited to transmit different data streams simultaneously at the same directions, same frequency, but with different PSs in the desired directions to increase the channel capacity, and with random PSs off the desired directions to enhance PLS. The proposed method has the capability of concurrently projecting independent signals into different specified spatial directions while simultaneously distorting signal constellation in all other directions. The symbol error rate (SER), secrecy rate, and the robustness of the proposed DM scheme are analyzed. Design examples for single- and multi-beam DM systems are also presented. Simulations corroborate that (1) the proposed method is more effective for PLS; (2) the proposed DM scheme is more power-efficient than the traditional artificial noise aided DM schemes; and (3) the channel capacity is significantly improved compared with conventional scalar antenna arrays.

The demand for higher data rate and better quality of service (QoS) in wireless communications was growing fast in the past few years. Obtaining these requirements becomes challenging for wireless communication systems due to the problems of channel multi-path fading, higher power and bandwidth limitations. One of the most promising solutions to this problem is Multiple Input Multiple Output (MIMO) system. This paper proposed a combined spatial multiplexing MIMO scheme with beamforming for high data rate wireless communication. The proposed transmission scheme combines the benefits of both techniques and the system was able to transmit parallel data streams as well as providing beamforming gain. Actually, these diverse techniques, share the same requirement of multiple antenna elements, but differ in the antenna element spacing necessary for the different schemes to work. Thus, smart antenna array was proposed as a possible solution and was adopted at the both transmitter and the receiver. The hybrid technique provides higher spectral efficiency and improve better Bit error rate (BER) of the system than the conventional MIMO, spatial multiplexing and beamforming techniques under the same simulation environment.

With large available continuous bandwidth, millimeter wave (mmWave) bands hold promise as a carrier frequency for fifth generation (5G) wireless communications. Moreover, mmWave bands also play an important role in radar detections. Based on this observation, we propose an mmWave wireless communication and radar detection integrated network architecture for railways, not only to increase the capacity of railway wireless communication systems, but also to realize train operation environment detection to enhance train operation safety. To overcome the aggravated path loss in mmWave bands, directional beamforming is generally used to concentrate signal radiation energy both in wireless communications and radar detections. Nevertheless, for wireless communications, the signaling blind zone of directional beamforming makes it less effective in wireless link establishment and maintenance. Therefore, in this proposed integrated network, two frequency bands are employed, where omnidirectionally radiated licensed lower frequency bands carry critical signaling and data, and mmWave bands are time-division multiplexed to transmit large-volume communication data for trains, or to perform environment detection for enhancing train operation safety. To mitigate handovers and to increase baseband processing resource utilization in railway scenarios, the proposed integrated network is deployed based on the cloud radio access network (C-RAN) architecture, where both licensed lower frequency band radio remote units (RRUs) and mmWave band RRUs are connected to a building baseband unit (BBU) pool through high-speed backhauls. Besides, physical (PHY) frame structures and up/downlink communication signaling procedures are designed for this proposed integrated network. Performance analysis results have demonstrated that the proposed integrated network can highly increase the capacity for railway wireless communication systems and achieve high distance and angular resolution for radar detections.

Multiple input multiple output (MIMO) technique that requires multiple antennas at both transmitter and the receiver is a key technology to meet the peak data rates and spectral efficiency targets of long term evolution (LTE) systems. MIMO is a widely researched topic, and understanding of MIMO concepts have an interaction with other essential enhancement mechanisms in the system including link adaptation, resource scheduling, inter stream interference, rank of the channel, etc. This paper mainly aims to target the MIMO mode adaptation strategies in LTE systems by considering the rank and other key parameters like antenna correlation, doppler frequency, bit rate, throughput, etc. 3GPP LTE rel-8 has adopted seven MIMO modes and variable modulation and coding schemes (MCS) to effectively utilize the available resources for maximizing the throughput of the system. In this paper, new techniques for obtaining appropriate rank and a new MIMO mode switching algorithm to maximize data rate of the user equipment (UE) for a given channel consider at the receiver with reasonable complexity, and there by improving the average system throughput are proposed. The paper considers only four MIMO modes namely transmit diversity, open loop spatial multiplexing (OLSM), closed loop spatial multiplexing (CLSM) and beam-forming with different modulation levels. MIMO mode switching is done based on throughput value between open loop modes namely transmit diversity and OLSM for high mobility UE in the presence of co channel interference (CCI). Similarly, mode switching is done between closed loop modes namely CLSM and beam-forming for pedestrian UE in the presence of CCI. Simulation results are provided to illustrate the performance benefits of the proposed algorithm. The simulation results reveal that these new techniques improves the system throughput significantly.

Space-time block code and spatial multiplexing are promising approaches that exploit the multiple input multiple output (MIMO) channel to provide high diversity and multiplexing gain without sacrifice in bandwidth. In this paper, a hybrid MIMO scheme for orthogonal frequency division multiplexing systems is proposed to achieve various multiplexing gains according to the channel condition. The existing hybrid MIMO schemes are appropriate for limited integer multiplexing rates without taking into account the channel condition, whereas the proposed scheme can attain various multiplexing rates according to the channel condition.