双向HFC网上行传输的技术问题及其对策

利用HFC网络开展交互式业务时 ,在回传通道上存在回传噪声 ,分析了回传噪声的种类、特征及噪声的形成原因、侵入途径等 ,提出了为解决回传噪声的问题所采取的方法和措施 ,以确保在双向网络上顺利实现交互式业务。

Driving Behavior Shaping Model in Road Traffic System

In order to give a new way for modeling driving behavior, identifying road traffic accident causation and solving a variety of road traffic safety problems such as driving errors prevention and driving behavior analysis, a new driving behavior shaping model is proposed, which could be used to assess the degree of effect of driving error upon road traffic safety. Driver behavior shaping model based on driving reliability and safety analysis could be used to identify the road traffic accident causation, to supply data for driver's behavior training, to evaluate driving procedures, to human factor design of road traffic system.

Quantum Secret Sharing Based on Chinese Remainder Theorem

A novel quantum secret sharing （QSS） scheme is proposed on the basis of Chinese Remainder Theorem （CRT）. In the scheme, the classical messages are mapped to secret sequences according to CRT equations, and distributed to different receivers by different dimensional superdense-coding respectively. CRT＇s secret sharing function, together with high-dimensional superdense-eoding, provide convenience, security, and large capability quantum channel for secret distribution and recovering. Analysis shows the security of the scheme.

Protocol for Trusted Channel Based on Portable Trusted Module

Web-based e-commerce applications need a trusted channel,which provides confidential communication,identity authentication and integrity assurance of endpoints,to guarantee the security of electronic transactions.A user-oriented trusted computing system based on Portable Trusted Module(PTM)is presented.Remote attestation is incorporated into Transport Layer Security(TLS)handshake protocol based on PTM so as to establish a trusted channel between two endpoints in network.This protocol can resist masquerading,trusted path and runtime attacks and propagate the trust in the computing system to the end user effectively.The test results of our proof-of-concept prototype show that our protocol for trusted channel is feasible for deployment in e-commerce applications on the Internet.

Radio Channel Measurements and Analysis at 2.4/5GHz in Subway Tunnels

There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment services(e.g.,Internet,etc.) to passengers as well.The wireless channel in tunnels is quite unique due to the confined space and the waveguide effects.Therefore,modeling the radio channel characteristics in tunnels is critically important for communication systems design or optimization.This paper investigates the key radio channel characteristics of a subway tunnel at 2.4 GHz and 5 GHz,such as the path loss,root mean square(RMS) delay spread,channel stationarity,Doppler shift,and channel capacity.The field measurements show that channel characteristics in tunnels are highly location-dependent and there exist abundant components in Doppler shift domain.In the straight section of the subway tunnel,the measured path loss exponents are close to1.6,lower than that in free space.

Deterministic quantum communication using the symmetric W state

This study proposes a new coding function for the symmetric W state. Based on the new coding function, a theoretical protocol of deterministic quanama communication （DQC） is proposed. The sender can use the proposed coding function to encode his/her message, and the receiver can perform the imperfect Bell measurement to obtain the sender＇s message. In comparison to the existing DQC protocols that also use the W class state, the proposed protocol is more efficient and also more practical within today＇s technology. Moreover, the security of this protocol is analyzed to show that any eavesdropper will be detected with a very high probability under both the ideal and the noisy quantum channel.

Robust quantum secure direct communication with a quantum one-time pad over a collective-noise channel

We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a collective-noise channel. The two photons in each logical qubit can be produced with a practically entangled source, i.e., a parametric down-conversion source with a beta barium borate crystal and a pump pulse of ultraviolet light. The information is encoded on each logical qubit with two logical unitary operations, which will not destroy the antinoise feather of the quantum systems. The receiver Bob can read out the sender's message directly with two single-photon measurements on each logical qubit, instead of Bell-state measurements, which will make these protocols more convenient in a practical application. With current technology, our two robust QSDC schemes are feasible and may be optimal ones.