Classical space-time coding methods, such as BLAST, STTC, and STBC, are coding methods based on perfect channel state information, and are decoded by coherent detection. In order to obtain the utilization rate of high-frequency bands and the gain of spatial diversity and multiplexing. However, when the network nodes move rapidly, the periodic pilot symbol channel estimation method has a large time delay. Especially when the number of transmitting antennas is relatively large, the channel training time is highly complex, and it is difficult to meet the requirements of coding accuracy. Based on the above considerations, this paper proposes a space-time-frequency coding method based on MIMOOFDM system. Compared with space-time coding, this space-time-frequency coding method makes full use of the frequency diversity gain of the MIMO-OFDM system to improve the performance of the system.
Visible light communication has advantages such as high speed, broadband, green, safety, and low cost. Moreover, visible light communication is not subject to electromagnetic interference, so it is useful in a wide range of application scenarios such as aviation, hospitals, and mines. However, due to the limited spectrum and coverage provided by a single LED, multiple LED coverage is adopted in the indoor layout to provide seamless connection, which also brings spectrum interference in overlapping areas. This paper proposes an indoor visible light interference suppression method based on the backward forward markup (BFM) algorithm. This method not only solves the problem of spectral interference, but also improves throughput while ensuring user fairness. The simulation results show that the BFM algorithm has brought significantly improvements in various aspects, with system throughput increased by 75% and fairness factor increased by 0.3.
KEYWORDS: Telecommunications, Data communications, Design and modelling, Computing systems, Optical fibers, Data transmission, Data conversion, Optical communications, Data processing, Signal processing
Aiming at the characteristics of the self-designed and developed Fiber Tree Bus (FTB) terminal, such as more terminals, more interactive data and various node communication protocols, an intelligent data monitoring terminal is designed by using FPGA and QT software of host computer, a high-speed data transmission system is constructed, which is used to monitor and locate the data transmitted on the optical fiber bus. The system is divided into data transmission module, data analysis module, data transmission module receiving all data flow on fiber data bus, data analysis module caches all data, abnormal location. The test results show that the bus terminal satisfies the requirement of monitoring all terminal nodes on the self-designed FTB system, and the system runs RS422, gigabit network, CAN and other communication data. The monitoring terminal can receive all communication data, can locate the abnormal condition of each node, and the system runs smoothly.
KEYWORDS: Telecommunications, Data communications, Data transmission, Control systems, Data conversion, Data storage, System integration, Optical fibers, Field programmable gate arrays, Signal processing
Aiming at the characteristics of the self-designed and developed fiber tree bus (FTB) terminal, such as more terminals, more interactive data and various node communication protocols, This paper designs an efficient bus controller, a practical and efficient instruction list, and Constructs A high-speed data transmission system, which is used to manage and control the data transmitted on the fiber bus. FTB layered structure, bus topology and the performance of real-time transmission are introduced. According to the application requirements of military vehicle-borne photoelectric system, the model of photoelectric information transmission system based on FTB is built, and the transmission performance of FTB based on this bus controller is tested. The compared results of analysis and test show that, FTB has a variety of real-time information transmission capacity, but also verified that the bus controller is efficient and practical,Finally, Transmission Delay Index and information interaction index are analyzed and tested.
Optical fiber bus technology is an important research direction in communication systems of electronic devices in special vehicle platforms. According to the requirements for communication quality between devices in special vehicle platforms, an optical fiber bus based on gigabit passive optical network topology is proposed. A data cache-based predictive weighted interpolated polling dynamic bandwidth allocation method is presented and investigated for the optical fiber bus’s upstream bandwidth allocation. The network controller establishes a weighted buffer area for the communication requirements in the polling period according to the type and data volume of the network terminal (NT) data stream and dynamically allocates the bandwidth of each optical NT to better meet the communication requirements for different data within the special device platform. Verification is done by means of OPNET software simulation and the establishment of a NT simulation test system in the laboratory. This proves that the proposed dynamic bandwidth allocation algorithm can reduce the end-to-end delay of RS422 port data by more than 50% and meet the Ethernet and controller area network port data delay requirements.
KEYWORDS: Optical fibers, Data transmission, Data communications, Time division multiplexing, Optical communications, Optical networks, Field programmable gate arrays, Passive optical networks, Fiber optic communications, Control systems
Passive Optical Network (PON), which possess the advantages of high efficiency, high speed and high bandwidth utilization, is a type of fiber channel technology that acquires the most concern. As a type of key technology in military weapon electronic system, the target of fiber channel data bus is to offer actual-time, high-speed and reliable communication link between instruments. In this article, a type of fiber channel data bus, which is based on PON topology, is raised and elaborated. The elaboration is concentrated on the designation of the topology and protocol used in the fiber channel data bus. On this basis, the research emphasis is the upstream Media Access Control (MAC) layer in the Network Terminal (NT) of the fiber channel data bus which is designed. Firstly, the upstream synchronization method and frame structure in GPON standards are analysed. Then, the upstream MAC layer control is actualized through Xilinx FPGA devices.
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