A novel method of quantum key distribution (QKD) based on hybrid fiber-wireless system is proposed in this paper. Quantum key from a center station (i.e., Alice) is transmitted through an optical fiber to a base station and then wirelessly forwarded to mobile nodes (i.e., Bobs). QKD protocol is implemented by using subcarrier intensity modulation, where binary phase shift keying (BPSK) signaling is used for encoding and direct detection with a dual-threshold receiver is employed for decoding. We derive the mathematical expressions for security analysis of the proposed system in terms of quantum bit error rate and ergodic secret-key rate taking into account the channel loss and receiver noise. The feasibility of the proposed QKD system is validated via the numerical results.
A novel method of quantum key distribution (QKD) based on hybrid fiber-wireless system is proposed in this paper. Quantum key from a center station (i.e., Alice) is transmitted through an optical fiber to a base station and then wirelessly forwarded to mobile nodes (i.e., Bobs). QKD protocol is implemented by using subcarrier intensity modulation, where binary phase shift keying (BPSK) signaling is used for encoding and direct detection with a dual-threshold receiver is employed for decoding. We derive the mathematical expressions for security analysis of the proposed system in terms of quantum bit error rate and ergodic secret-key rate taking into account the channel loss and receiver noise. The feasibility of the proposed QKD system is validated via the numerical results.
We examine the applicability of wireless indoor quantum key distribution (QKD) in hybrid quantum-classical networks. We propose practical configurations that would enable wireless access to such networks. The proposed scenarios would allow an indoor wireless user, equipped with a QKD-enabled mobile device, to communicate securely with a remote party on the other end of the access network. QKD signals, sent through wireless indoor channels, are combined with classical ones and sent over the same fiber link to the remote user. Dense wavelength-division multiplexing would enable the simultaneous transmission of quantum and classical signals over the same fiber. We consider the adverse effects of the background noise induced by Raman scattered light on the QKD receivers due to such an integration. In addition, we consider the loss and the background noise that arise from indoor environments. Decoy-state BB84 and measurement device-independent protocols are employed for the secret key rate analysis.
This paper aims to take a new look at a novel security solution for 5G-based Internet of things (IoT) networks using quantum key distribution (QKD). Quantum keys are created and sent from a key distribution server to IoT gateways thanks to radio-over-fiber (RoF) systems. More specifically, the raw key is encoded into the intensity of radio-frequency subcarrier before being sent to the gNB by optical fiber. It is then wirelessly forwarded to IoT gateways through radio frequency links. The major findings of the study reveal that the proposed system is an effective approach in order to distribute the quantum key with low quantum bit error rate and high secret key rate for 5G-based IoT networks.
Among all emerging quantum information technologies, quantum key distribution (QKD) is one of the most developed techniques. QKD harnesses the intrinsic laws of quantum mechanics to provide a method for distributing secret random keys, which can be used for data encryption and decryption between two intended users. QKD has already been demonstrated in different scenarios over optical fibre and in atmospheric channels. QKD has also been used for security assurance in several network settings, in addition of being commercially available today. Despite remarkable progress in QKD systems, convenient access to the developing quantum communications networks is still missing. Adopting QKD in mobile devices would enable such a service, particularly, in indoor environments. This is in line with the recent advancement in fabricating microchip-scale QKD devices, which would ease this incorporation into mobile devices. This work focuses on the access networks, and, in particular, it addresses the wireless mode of access in indoor environments for QKD networks. We find a practical regime of operation, where, in the presence of external light sources and loss, secret keys can be exchanged. We then propose practical configurations that would enable wireless access to hybrid quantum-classical networks. The proposed setups would allow an indoor wireless user, equipped with a QKD-enabled mobile device, to communicate securely with a remote party on the other end of the access network. We account for adverse effects of the background noise induced by Raman scattered light on the QKD receivers due to the transmission of both quantum and classical signals over the same fibre. In addition, we consider the loss and the background noise that arise from indoor environments. We consider a number of discrete and continuous-variable QKD protocols and study their performance in different scenarios. In our analysis we consider the asymptotic scenario, as well as the finite-size key effects. In the former case, an infinite number of signals are assumed to be exchanged between the sender and the recipient, whereas in the latter, which represents the
practical scenario, a finite number of signals are exchanged between the two users. Our results indicate that a feasible regime of operation for wireless QKD exists. This makes the QKD technologies available to end users of a communications network.
This paper proposes a novel free-space quantum key distribution (QKD) system using subcarrier intensity-modulation (SIM) binary phase-shift-keying (BPSK) and dual-threshold/direct-detection (DT/DD) receiver with an avalanche photodiode (APD). The proposed system enables the adoption of well-developed analytical models in conventional free-space optical (FSO) communications and achieves the QKD function with a simple configuration. We analytically investigate the design criteria for transmitter and receiver, in particular, the modulation depth and the setting for dual-threshold in the context of security requirement of QKD systems. The quantum bit error rate (QBER) and the ergodic secret-key rate of the proposed system are analytically derived in closed-form expressions, considering the channel loss, atmospheric turbulence modeled by the log-normal distribution, and receiver noises. Monte-Carlo (M-C) simulations are also implemented to validate the analytical results, and numerical results confirm the feasibility of the proposed system.
This paper proposes a novel design and analyzes security performance of quantum key distribution (QKD) protocol over free-space optics (FSO). Unlike conventional QKD protocols based on physical characteristics of quantum mechanics, the proposed QKD protocol can be implemented on standard FSO systems using subcarrier intensity modulation binary phase shift keying and direct detection with a dual-threshold receiver. Under security constraints, the design criteria for FSO transmitter and receiver, in particular, the modulation depth and the selection of dual-threshold detection, respectively, is analytically investigated. For the security analysis, quantum bit error rate, ergodic secret-key rate, and final key-creation rate are concisely derived in novel closed-form expressions in terms of finite power series, taking into account the channel loss, atmospheric turbulence-induced fading, and receiver noises. Furthermore, Monte-Carlo simulations are performed to verify analytical results and the feasibility of the proposed QKD protocol.
This paper aims at proposing a novel satellite quantum key distribution (QKD) system for vehicular networks. Quantum key from a satellite (i.e., a trusted node) is transmitted through a free-space optical (FSO) channel to a high-attitude platform (HAP) using radio-over-FSO (RoFSO) technique. HAP playing a role as a relaying node forwards the key to moving vehicles via millimeter-wave (MMW) channel. Key information generated is encoded on MMW subcarrier using binary phase shift keying (BPSK) signaling and then recovered at the receiver thanks to a dual-threshold detector. We derive the mathematical expressions for security analysis of the proposed QKD system in terms of quantum bit error rate and ergodic secret-key rate taking into account the channel loss and receiver noise. The numerical results confirm the feasibility of the proposed QKD system.