Physical layer security for NOMA: requirements, merits, challenges, and recommendations

Non-orthogonal multiple access (NOMA) has been recognized as one of the most significant enabling technologies for future wireless systems due to its eminent spectral efficiency, its ability to provide an additional degree of freedom for ultra reliable low latency communications (URLLC), and grant free random access. Meanwhile, physical layer security (PLS) has got much attention for future wireless communication systems due to its capability to efficiently complement the cryptography-based algorithms for enhancing overall security of the communication system. In this article, security design requirements for downlink power domain NOMA and solutions provided by PLS to fulfil these requirements are discussed. The merits and challenges which were encountered while employing PLS to NOMA are identified. Finally, future recommendations and prospective so lutions are also presented.No sponso

Wireless communication, sensing, and REM: A security perspective

The diverse requirements of next-generation communication systems necessitate awareness, flexibility, and intelligence as essential building blocks of future wireless networks. The awareness can be obtained from the radio signals in the environment using wireless sensing and radio environment mapping (REM) methods. This is, however, accompanied by threats such as eavesdropping, manipulation, and disruption posed by malicious attackers. To this end, this work analyzes the wireless sensing and radio environment awareness mechanisms, highlighting their vulnerabilities and provides solutions for mitigating them. As an example, the different threats to REM and its consequences in a vehicular communication scenario are described. Furthermore, the use of REM for securing communications is discussed and future directions regarding sensing/REM security are highlighted

FDD massive MIMO downlink channel estimation via selective sparse coding over AOA/AOD cluster dictionaries

Sparse coding over a redundant dictionary has recently been used as a framework for downlink channel estimation in frequency division duplex massive multiple-input multiple-output antenna systems. This usage allows for efficiently reducing the inherently high training and feedback overheads. We present an algorithm for downlink channel estimation via selective sparse coding over multiple cluster dictionaries. A channel training set is divided into clusters based on the angle of the arrival/departure of the majority physical subpaths corresponding to each channel tap. Then, a compact dictionary is trained in each cluster. Channel estimation is done by first identifying the channel cluster and then using its dictionary for reconstruction. This selective sparse coding allows for adaptive regularization via sparse model selection, thereby offering additional regularization to the ill-posed channel estimation problem. We empirically validate the selectivity of the cluster dictionaries. Simulation results show the advantage of the proposed algorithm in achieving better estimation quality at lower computational cost, as compared the case of using standard sparse coding.IEE

Enhancing physical layer security of OFDM systems using channel shortening

This work presents a simple, spectral and power efficient scheme for providing secure OFDM communication system using channel shortening. The basic concept is to utilize a channel shortening technique, whose design is based on the channel of the legitimate user (Bob), in such a way that the length of the effective channel is made equal to or less than the cyclic prefix (CP) at Bob only, while the length of the effective channel at the illegitimate receiver (Eve) is greater than CP. Thus, this causes inter-symbol-interference (ISI), loss of orthogonality, and overall performance degradation at Eve. The simulation results show that the presented technique can provide a significant BER performance gap between Bob and Eve, and can provide Quality of Service (QoS) based security. The design is shown to be robust against channel imperfections and can provide spectral and power efficiency beside enhancing security.Institute of Electrical and Electronics EngineersIEEE Communications Societ

Secret key generation using channel quantization with SVD for reciprocal MIMO channels

The generation of secret keys from reciprocal wireless channel by exploiting their randomness nature, is an emerging area of interest to provide secure communication. One of the main challenges in this domain is to increase the secret key length, extracted from the shared channel coefficients between two legitimate communication parties, while maintaining its randomness and uniformity. In this work, we develop a practical key generation method, based on channel quantization with singular value decomposition (CQSVD), which is capable of significantly increasing the generated secret key in MIMO systems. This is achieved through quantizing the phases and amplitudes of the estimated MIMO channel coefficient's matrix by using an alternative form of SVD, where the key sequence is extracted from the orthogonal basis functions of the decomposed channel. In this method, it is shown that for an M ×M antenna system, with M2 independent channel fading coefficients, a secret key sequence of length 2M3 can be generated. The extracted key sequence is transformed to a random phase sequence, which is then used to manipulate the transmitted data on a symbol level basis rather than bit level-basis, to provide more secure communication. The comparative simulation results show that the proposed CQSVD method outperforms the state of the art secret key generation methods

Physical layer security for wireless sensing and communication

Wireless physical layer (PHY) security has attracted much attention due to the broadcast nature of the wireless medium and its inherent vulnerability to eavesdropping, jamming, and interference. Physical Layer Security for Wireless Sensing and Communication covers both communication and sensing security from a broad perspective. The main emphasis is on PHY security, although other security measures are covered for the sake of completeness and as a step towards cross-layer security and cognitive security vision. After discussing the features of wireless channels from both the communication and sensing perspectives, the book details their exploitation for secure transmission utilizing various approaches. Wireless sensing and radio environment concepts are also addressed, along with the related security implications in terms of eavesdropping, disruption, manipulation, and, in general, the exploitation of wireless sensing by unauthorised users. Several solutions for these threats from the domains of wireless communication, military radars, and machine learning, are discussed. The book provides valuable information to researchers in academia and industry, as well as engineers, developers, and advanced students in the field of cybersecurity

Gelecekteki kablosuz iletişim sistemleri için gizli dinlemeye karşı fiziksel katman güvenlik teknikleri

The inherent broadcast characteristics of wireless communication make it vulnerable to passive eavesdropping. Conventionally, security techniques in the upper layers like cryptography-based techniques have been employed for secure transmission. However, such security techniques may not be adequate for future decentralized networks due to their high complexity of implementation and computation. Furthermore, the emergence of powerful computing devices makes these techniques vulnerable to sophisticated adversaries. To cope up with these problems, physical layer security (PLS) techniques have attracted a lot of attention. PLS techniques exploit the dynamic features of wireless communications, for example, the randomness of the channel, interference, and noise, etc., to restrict the eavesdropper from decoding the data while ensuring the successful decoding of data for the legitimate user. In this thesis, novel security techniques are proposed and developed based on the physical layer of wireless communication to provide secure communication against eavesdropper. The main approaches in the conducted research include the security techniques for the applications in the following domains: multiple-input-multiple-output (MIMO), cooperative communication, orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiplexing with index modulation (OFDM-IM), cognitive radio (CR), non-orthogonal multiple access (NOMA), and heterogeneous networks. Moreover, an intelligent framework for physical layer security is also presented.Kablosuz iletişimin doğasında bulunan yayılım özellikleri, onu pasif dinlemeye karşı savunmasız kılmaktadır. Geleneksel olarak, güvenli bir iletim için üst katmanlarda kriptografiye dayalı güvenlik teknikleri kullanılmıştır. Bununla birlikte, bu tür güvenlik teknikleri, yüksek uygulama ve hesaplama karmaşıklıkları nedeniyle gelecekteki merkezi olmayan ağlar için yeterli olmayabilmektedir. Ayrıca, güçlü bilgi işlem cihazlarının ortaya çıkışı, bu teknikleri ileri teknolojiye dayalı rakiplere karşı savunmasız hale getirir. Bu sorunların üstesinden gelmek için, Fiziksel Katman Güvenliği (PLS) teknikleri büyük ilgi görmüştür. PLS teknikleri, meşru kullanıcı için verilerin başarılı bir şekilde çözülmesini sağlarken, gizli dinleyicinin verilerin kodunu çözmesini kısıtlamak için, kanalın rasgeleliği, girişim ve gürültü gibi dinamik özelliklerinden yararlanır. Bu tezde, dinleyicilere karşı güvenli iletişim sağlamak için kablosuz iletişimin fiziksel katmanına dayalı olarak yeni güvenlik teknikleri önerilmiş ve geliştirilmiştir. Yürütülen araştırmadaki ana yaklaşımlar, aşağıdaki alanlardaki uygulamalar için güvenlik tekniklerini içermektedir: Çoklu-giriş çoklu-çıkış (MIMO), işbirliğine dayalı iletişim, Dikey Frekans Bölmeli Çoklama (OFDM), İndeks Modülasyonlu Dikey Frekans Bölmeli Çoklama (OFDM-IM), Bilişsel Radyo (CR), Dikey Olmayan çoklu Erişim (NOMA) ve heterojen ağlar. Ayrıca, fiziksel katman güvenliği için akıllı bir çerçeve de sunulmaktadır

Multi-cell, multi-user, and multi-carrier secure communication using non-orthogonal signals’ superposition with dual-transmission for IoT in 6G and beyond

Considering the advancements of the internet of things (IoT) in 6G and beyond communications, data transmission security in IoT devices has received extensive interest because of their significant features, such as low computational complexity, led by low power requirements. In such devices, the conventional cryptographic techniques may fail to provide secure communication. To fight this drawback, physical layer security (PLS) has remarkable potential to provide security solutions suitable for such applications. In this work, a highly effective PLS technique is proposed for providing secure communication against external and internal eavesdroppers in a downlink multi-cell, multi-user, and multi-carrier IoT communication system. In our proposed system, we considered two base stations, where each base station uses a single radio frequency (RF) chain to link two antennas that are used for the transmission of data. Further, we transmit the data in two rounds, and each round of transmission occurs through a single active antenna of each base station. A different antenna is used for each round of transmission to communicate with two single antenna IoT devices/users in the presence of a passive eavesdropper. In the proposed algorithm, frequency selective channel-based pre-coder matrices and the dual transmission approach are jointly employed. The dual-transmission is performed simultaneously from two base stations to provide security against internal and external eavesdroppers. The proposed system is suitable for IoT-based applications. Also, the potential capabilities of our proposed algorithm are proved by extensive mathematical and simulation analysis.No sponso