A multi-dimensional modulation scheme in inter-satellite quantum communication based on pulse position modulation and polarization encoding is put forward and designed. By this way we can send additional classical signal simultaneously when transmitting quantum signal. The basic principle of multi-dimensional modulation scheme is introduced. Simulation experiment is performed using Optisystem and Matlab simultaneously. The binary sequence before modulation and that after demodulation are compared and analyzed. The error bit rate, eye diagram and quality factor of classical optical date are obtained. Stabilities of classical optical signal during the transmission are tested. The results show that this multi-dimensional modulation scheme can decrease the numbers of information channels needed, increase information transmission efficiency and reduce the demands for power load systematic complexity in communication terminals. The proposed coexistence system is confirmed to be effective and applicable.
A multi-dimensional modulation scheme in inter-satellite quantum communication based on pulse position modulation and polarization encoding is put forward and designed. By this way we can send additional classical signal simultaneously when transmitting quantum signal. The basic principle of multi-dimensional modulation scheme is introduced. Simulation experiment is performed using Optisystem and Matlab simultaneously. The binary sequence before modulation and that after demodulation are compared and analyzed. The error bit rate, eye diagram and quality factor of classical optical date are obtained. Stabilities of classical optical signal during the transmission are tested. The results show that this multi-dimensional modulation scheme can decrease the numbers of information channels needed, increase information transmission efficiency and reduce the demands for power load systematic complexity in communication terminals. The proposed coexistence system is confirmed to be effective and applicable.
A free space quantum communication multi-dimensional modulation system based on pulse position modulation and polarization encoding is put forward and designed and is used to send quantum information and classical information simultaneously. Atmospheric channel model and coexistence system model is built. We perform a simulation experiment for transmitting signal in atmospheric, using Optisystem and Matlab together. The binary sequence before modulation and that after demodulation are compared and analyzed. The error bit rate, eye diagram and quality factor of classical optical date are obtained. Stabilities of classical optical signal during the transmission are tested. The results show that this multi-dimensional modulation system can decrease the numbers of information channels needed and reduce the demands for power load and systematic complexity in communication terminals. The proposed quantum communication system is confirmed to be effective and applicable.
We propose a terahertz continuous-variable quantum key distribution protocol using pulse position modulation, which enables simultaneous quantum and classical communication for inter-satellite links. In this scheme, classical information is conveyed through the relative positioning of encoded pulses while quantum information is encoded using Gaussian modulation to generate thermal terahertz (THz) signals. Coherent detection is employed to measure all the relevant parameters. Extensive multi-parameter simulations were conducted to validate the protocol, examining the bit error rate, secret key rate, and transmission distance under varying pulse position modulation (PPM) settings and other parameters. The results demonstrate that the protocol is feasible and represents an effective method for quantum key distribution. The proposed approach offers a promising pathway for the deployment of inter-satellite quantum communication networks.
In order to study the quantum communication signaling system and realize quantum communication between multiple users,a kind of differential phase encoding scheme for the polarization state of quantum signaling is proposed,and details of the encoding process are described.The sender uses polarization states of different photons to represent different signalings,and then implements phase modulation for the photons and encodes the quantum signaling based on the phase difference between the impulses before and affter encoding.In order to complete the decoding,two optical pulses occur interference at the beam splitter.The signal 0 or 1 can be detected by different detectors according to their phase difference.According to the Gaussian pulse distribution,quantitative relationship amongthe quantum bit error rate caused by the pulse delay to differential phase of encoding system,pulse width and delay time in photonic transmission process are enduced.Besides,quantum bit error rate of single-photon pulsesdistribution of Gaussian is calculated in determined timing jitter.Finally,quantum signaling encoded efficiency and bit error rate are analyzed and simulated.The results show that the encoded efficiency of proposed coding scheme can reach 75% that can satisfy the needs of quantum mobile communication.
Classical communication and quantum key distribution (QKD) share similarities in signal modulation, transmission, and reception, providing a foundation for their integration. This paper proposes a novel protocol for simultaneous quantum and classical communication in short-distance Continuous-Variable QKD (CV-QKD). The protocol employs polarization-state encoding of classical information with weak coherent states, allowing for the concurrent transmission of quantum and classical data without the need for classical optical pulses. A noise model is established to analyze the system’s excess noise under varying modulation variances, along with the performance of both classical and quantum communication. Simulation results indicate that our proposed protocol can achieve a secure key rate of no less than 1.05Mbps over a distance of 20km.
Abstract Satellite identification is a form of space quantum information, which refers to the use of artificial earth satellites as the transmitting station between earth communication stations to perform satellite identification to construct a space quantum information system. However, at this stage, a single form of identification cannot meet the needs of various aspects such as the development of the information society. And mobile broadband services. Based on this, this paper has carried out research on the construction of space quantum information system based on satellite recognition. This paper firstly introduces the research significance of space quantum information transmission based on satellite identification, and then analyzes the research status of space information system based on satellite identification and the research status of space quantum information system based on satellite identification at home and abroad. Aiming at the problem of asymmetrical transmission of space information, this paper proposes, a spatial asymmetric transmission scheme based on layered modulation and network coding, and in view of the low communication quality caused by the influence of weather and surrounding environment on the space-based communication channel, this paper proposes an adaptive transmission scheme of spatial information based on satellite cooperation. The survey results show that under the MNC strategy and the traditional zero-padded strategy, the end-to-end bit error rate performance of S2 is not much different. As the signal-to-noise ratio continues to increase to 30dB, the two are basically the same. In the whole range of k value, the access probability of the MNC strategy is equal to a constant 0.67 and remains unchanged. When k=1, under the OUS scheme, it shows that the two source nodes have the same probability of accessing the channel, and the access probability is 50%, which is 16.7% lower than that of the MNC scheme.
The binary (one-bit-per-photon) encoding that most existing quantum key distribution (QKD) protocols employ puts a fundamental limit on their achievable key rates, especially under high channel loss conditions associated with long-distance fiber-optic or satellite-to-ground links. Inspired by the pulse-position-modulation (PPM) approach to photon-starved classical communications, we design and demonstrate the first PPM-QKD, whose security against collective attacks is established through continuous-variable entanglement measurements that also enable a novel decoy-state protocol performed conveniently in post processing. We achieve a throughput of 8.0 Mbit/s (2.5 Mbit/s for loss equivalent to 25 km of fiber) and secret-key capacity up to 4.0 bits per detected photon, thus demonstrating the significant enhancement afforded by high-dimensional encoding. These results point to a new avenue for realizing high-throughput satellite-based or long-haul fiber-optic quantum communications beyond their photon-reception-rate limits.