China's Communications and Broadcasting Satellites

China is a developing countrywith a large population and the e-conomic development level in theprovinces and the autonomous re-gions is quite different.On theother hand,the transmission ofthe broadcasting and TV pro-grams via satellites has the follow-ing advantages:large coverage,high transmission quality and rea-sonable cost-effectiveness.There-fore,the satellite communicationsis the most advanced and effectiveway to realize full territory coverage of broadcasting and TV pro-grams in China. China began to develop com-munications satellites immediatelyafter it successfully launched

Machine-Learning Based Packet Switching Method for Providing Stable High-Quality Video Streaming in Multi-Stream Transmission

Broadcasting gateway equipment generally uses a method of simply switching to a spare input stream when a failure occurs in a main input stream.However,when the transmission environment is unstable,problems such as reduction in the lifespan of equipment due to frequent switching and interruption,delay,and stoppage of services may occur.Therefore,applying a machine learning(ML)method,which is possible to automatically judge and classify network-related service anomaly,and switch multi-input signals without dropping or changing signals by predicting or quickly determining the time of error occurrence for smooth stream switching when there are problems such as transmission errors,is required.In this paper,we propose an intelligent packet switching method based on the ML method of classification,which is one of the supervised learning methods,that presents the risk level of abnormal multi-stream occurring in broadcasting gateway equipment based on data.Furthermore,we subdivide the risk levels obtained from classification techniques into probabilities and then derive vectorized representative values for each attribute value of the collected input data and continuously update them.The obtained reference vector value is used for switching judgment through the cosine similarity value between input data obtained when a dangerous situation occurs.In the broadcasting gateway equipment to which the proposed method is applied,it is possible to perform more stable and smarter switching than before by solving problems of reliability and broadcasting accidents of the equipment and can maintain stable video streaming as well.

Cryptanalysis and improvement of quantum broadcast communication and authentication protocol with a quantum one-time pad

The security of quantum broadcast communication（QBC） and authentication protocol based on Greenberger–Horne–Zeilinger（GHZ） state and quantum one-time pad is analyzed. It is shown that there are some security issues in this protocol.Firstly, an external eavesdropper can take the intercept–measure–resend attack strategy to eavesdrop on 0.369 bit of every bit of the identity string of each receiver without being detected. Meanwhile, 0.524 bit of every bit of the secret message can be eavesdropped on without being detected. Secondly, an inner receiver can take the intercept–measure–resend attack strategy to eavesdrop on half of the identity string of the other＇s definitely without being checked. In addition, an alternative attack called the CNOT-operation attack is discussed. As for the multi-party QBC protocol, the attack efficiency increases with the increase of the number of users. Finally, the QBC protocol is improved to a secure one.

Quantum broadcast communication and authentication protocol with a quantum one-time pad

A quantum broadcast communication and authentication protocol with a quantum one-time pad based on the Greenberger-Horne-Zeilinger state is proposed. A binary string is used to express the identity of the receiver, which is encoded as a single sequence of photons. The encoded photon sequence acts as a detection sequence and implements au- thentication. An XOR operation serves as a one-time pad and is used to ensure the security of the protocol. The binary string is reused even in a noisy channel and proves to be unconditionally secure. In contrast with the protocols proposed by Wang et al. [Chin. Phys. 16 1868 （2007）] and Yang et al. [Chin. Phys. B 19 070304 （2010）], the protocol in this study implements the identity authentication with a reusable binary string; no hash function or local unitary operation is used. The protocol in this study is also easier to implement and highly efficient without losing security.

Quantum broadcast communication with authentication

Two simple quantum broadcast communication schemes are proposed. A central party can broadcast his secret message to all the legitimate receivers simultaneously. Compared with the three schemes proposed recently （Wang et al. 2007 Chin. Phys. 16 1868）, the proposed schemes have the advantages of consuming fewer quantum and classical resources, lessening the difficulty and intensity of necessary operations, and having higher efficiency.

Quantum broadcast communication

Broadcast encryption allows the sender to securely distribute his/her secret to a dynamically changing group of users over a broadcast channel. In this paper, we just take account of a simple broadcast communication task in quantum scenario, in which the central party broadcasts his secret to multi-receiver via quantum channel. We present three quantum broadcast communication schemes. The first scheme utilizes entanglement swapping and Greenberger- Horne-Zeilinger state to fulfil a task that the central party broadcasts the secret to a group of receivers who share a group key with him. In the second scheme, based on dense coding, the central party broadcasts the secret to multi-receiver, each of which shares an authentication key with him. The third scheme is a quantum broadcast communication scheme with quantum encryption, in which the central party can broadcast the secret to any subset of the legal receivers.

X-Hamiltonian Surface Broadcast Algorithm

Broadcast is one of the most important approach in distributed memory parallel computers that is used to find a routing approach from one source to all nodes in the mesh. Broadcasting is a data communication task in which corresponds to one-to-all communication. Routing schema is the approach used to determine the road that is used to send a message from a source node to destination nodes. In this paper, we propose an efficient algorithm for broadcasting on an all-port wormhole-routed 3D mesh with arbitrary size. Wormhole routing is a fundamental routing mechanism in modern parallel computers which is characterized with low communication latency. We show how to apply this approach to 3-D meshes. In wormhole, routing large network packets are broken into small pieces called FLITs (flow control digits). The destination address is kept in the first flit which is called the header flit and sets up the routing behavior for all subsequent flits associated with the packet. In this paper, we introduce an efficient algorithm, X-Hamiltonian Surface Broadcast (X-HSB) which uses broadcast communication facility with deadlock-free wormhole routing in general three dimensional networks. In this paper, the behaviors of this algorithm are compared to the previous results using simulation;our paradigm reduces broadcast latency and is simpler. The results presented in this paper indicate the advantage of our proposed algorithm.

Novel THP algorithms with minimum BER criterion for MIMO broadcast communications

In this article, two novel Tomlinson-Harashima precoding （THP） algorithms are proposed at the downlink broadcast channel of multi-user multiple-input multiple-output （MIMO） systems. The optimality criterion is the minimization of the bit error rate （BER） at the receiver with a constraint on the overall transmitted power. In these algorithms, transmit power allocation （TPA） matrix is introduced to the traditional THP algorithms as part of the precoding matrix. This leads to a power loading operation based on substreams signal to interference-plus-noise ratio （SINR） and results in improvement of the error rate performance compared with traditional THP algorithms. When the precoding loss factor is considered, further performance improvement is achieved by the enhanced algorithm.

Universal and General Quantum Simultaneous Secret Distribution with Dense Coding by Using One-Dimensional High-Level Cluster States

A universal and general quantum simultaneous secret distribution(QSSD)protocol is put forward based on the properties of the one-dimensional high-level cluster states,in which one sender dispatches different high-level classical secret messages to many users at the same time.Due to the idea of quantum dense coding,the sender can send different two-dit classical messages(two d-level classical numbers)to different receivers simultaneously by using a one-dimensional d-level cluster state,which means that the information capacity is up to the maximal.To estimate the security of quantum channels,a new eavesdropping check strategy is put forward.Meanwhile,a new attack model,the general individual attack is proposed and analyzed.It is shown that the new eavesdropping check strategy can effectively prevent the traditional attacks including the general individual attack.In addition,multiparty quantum secret report(MQSR,the same as quantum simultaneous secret submission(QSSS))in which different users submit their different messages to one user simultaneously can be gotten if the QSSD protocol is changed a little.