다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

(1963). Cybernetics, or Control and Communication in the Animal and the Machine. Technometrics: Vol. 5, No. 1, pp. 128-130.

Cybernetics, or Control and Communication in the Animal and the Machine

Providing ubiquitous connectivity to diverse device types is the key challenge for 5G and beyond 5G (B5G). Unmanned aerial vehicles (UAVs) are expected to be an important component of the upcoming wireless networks that can potentially facilitate wireless broadcast and support high rate transmissions. Compared to the communications with fixed infrastructure, UAV has salient attributes, such as flexible deployment, strong line-of-sight (LoS) connection links, and additional design degrees of freedom with the controlled mobility. In this paper, a comprehensive survey on UAV communication towards 5G/B5G wireless networks is presented. We first briefly introduce essential background and the space-air-ground integrated networks, as well as discuss related research challenges faced by the emerging integrated network architecture. We then provide an exhaustive review of various 5G techniques based on UAV platforms, which we categorize by different domains including physical layer, network layer, and joint communication, computing and caching. In addition, a great number of open research problems are outlined and identified as possible future research directions.

UAV Communications for 5G and Beyond: Recent Advances and Future Trends

Massive access, also known as massive connectivity or massive machine-type communication (mMTC), is one of the main use cases of the fifth-generation (5G) and beyond 5G (B5G) wireless networks. A typical application of massive access is the cellular Internet of Things (IoT). Different from conventional human-type communication, massive access aims at realizing efficient and reliable communications for a massive number of IoT devices. Hence, the main characteristics of massive access include low power, massive connectivity, and broad coverage, which require new concepts, theories, and paradigms for the design of next-generation cellular networks. This paper presents a comprehensive survey of massive access design for B5G wireless networks. Specifically, we provide a detailed review of massive access from the perspectives of theory, protocols, techniques, coverage, energy, and security. Furthermore, several future research directions and challenges are identified.

Massive Access for 5G and Beyond

Rapid development of supercomputers and the prospect of quantum computers are posing increasingly serious threats to the security of communication. Using the principles of quantum mechanics, quantum communication offers provable security of communication and is a promising solution to counter such threats. Quantum secure direct communication (QSDC) is one important branch of quantum communication. In contrast to other branches of quantum communication, it transmits secret information directly. Recently, remarkable progress has been made in proof-of-principle experimental demonstrations of QSDC. However, it remains a technical feat to bring QSDC into a practical application. Here, we report the implementation of a practical quantum secure communication system. The security is analyzed in the Wyner wiretap channel theory. The system uses a coding scheme of concatenation of low-density parity-check (LDPC) codes and works in a regime with a realistic environment of high noise and high loss. The present system operates with a repetition rate of 1 MHz at a distance of 1.5 kilometers. The secure communication rate is 50 bps, sufficient to effectively send text messages and reasonably sized files of images and sounds. A quantum communication system demonstrated by researchers in China can transfer information securely in a realistic noisy environment. Emerging supercomputers and quantum computers may soon break the classical encryption methods that protect our information, highlighting the need for new cryptographic techniques based on quantum mechanics. Gui-Lu Long at Tsinghua University, Beijing, and co-workers have demonstrated a form of quantum secure direct communication (QSDC) that transfers information directly without the need to distribute keys, which are vulnerable to attacks. The team used a laser to generate single photons, which could carry secure quantum information such as text messages and image files over a distance of 1.5 kilometers. The information was decoded successfully by the receiver, even when the situation was made realistic by causing high photon loss or introducing errors due to noise.

/pdf/implementation-and-security-analysis-of-practical-quantum-4vwb67lkkp.pdf

Implementation and security analysis of practical quantum secure direct communication

Quantum secure direct communication (QSDC) is a unique technique, which supports the secure transmission of confidential information directly through a quantum channel without the need for a secret key and for ciphertext. Hence this secure communication protocol fundamentally differs from its conventional counterparts. In this article, we report the first measurement-device-independent (MDI) QSDC protocol relying on sequences of entangled photon pairs and single photons. Explicitly, it eliminates the security loopholes associated with the measurement device. Additionally, this MDI technique is capable of doubling the communication distance of its conventional counterpart operating without using our MDI technique. We also conceive a protocol associated with linear optical Bell-basis measurements, where only two of the four Bell-basis states could be measured. When the number of qubits in a sequence reduces to 1, the MDI-QSDC protocol degenerates to a deterministic MDI quantum key distribution protocol.

/pdf/measurement-device-independent-quantum-secure-direct-106yba3foo.pdf

Measurement-device-independent quantum secure direct communication

Security in communication is vital in modern life. At present, security is realized by an encryption process in cryptography. It is unbelievable if a secure communication is achievable without encryption. In quantum cryptography, there is a unique form of quantum communication, quantum secure direct communication, where secret information is transmitted directly over a quantum channel. Quantum secure direct communication is drastically distinct from our conventional concept of secure communication, because it does not require key distribution, key storage and ciphertext transmission, and eliminates the encryption procedure completely. Hence it avoids in principle all the security loopholes associated with key and ciphertext in traditional secure communications. For practical implementation, defects always exist in real devices and it may downgrade the security. Among the various device imperfections, those with the measurement devices are the most prominent and serious ones. Here we report a measurement-device-independent quantum secure direct communication protocol using Einstein-Podolsky-Rosen pairs. This protocol eradicates the security vulnerabilities associated with the measurement device, and greatly enhances the practical security of quantum secure direct communication. In addition to the security advantage, this protocol has an extended communication distance, and a high communication capacity.

Measurement-device-independent quantum communication without encryption

Security of quantum secure direct communication based on Wyner's wiretap channel theory

In this paper, we investigate the downlink cooperative multigroup multicast transmission in the integrated terrestrial-satellite network, in which base stations (BSs) and the satellite provide the multicast service for ground users in a cooperative manner while reusing the entire bandwidth. For both terrestrial BSs and the satellite, multiantennas are equipped and beamforming techniques are utilized for improving the system performance. Based on the architecture, we formulate a weighted max–min fair (MMF) beamforming design problem to jointly optimize the beamforming vectors of BSs and the satellite, which is solved based on the relation between the quality of service problem and the MMF problem. When it comes to the large scale case, where large numbers of BSs are distributed within the coverage of the satellite, we propose a time division cooperative multigroup multicast scheme consisting of two phases for the BSs and the satellite. Then, an iterative algorithm is proposed to solve the weighted MMF problem in the time division case. Finally, numerical results are provided to evaluate the cooperative multicast schemes as well as the proposed algorithms.

Liuguo Yin

Papers

Implementation and security analysis of practical quantum secure direct communication

Measurement-device-independent quantum secure direct communication

Measurement-device-independent quantum communication without encryption

Security of quantum secure direct communication based on Wyner's wiretap channel theory

Cooperative Multigroup Multicast Transmission in Integrated Terrestrial-Satellite Networks