随着以太网数据传输技术的广泛应用,数据传输速率不断地提升,传统的对时技术难以满足现代通信系统中实时传输的精度需求,网络业界提出了精密时钟同步协议标准(IEEE Standard for a Precision Clock Synchronization Protocol,IEEE1588)...随着以太网数据传输技术的广泛应用,数据传输速率不断地提升,传统的对时技术难以满足现代通信系统中实时传输的精度需求,网络业界提出了精密时钟同步协议标准(IEEE Standard for a Precision Clock Synchronization Protocol,IEEE1588),该标准采用精密时钟同步协议(Precision Time Protocol,PTP),精度可达微秒级。针对网络传输实时性的需求,阐述了PTP协议原理,通过搭建试验平台测试了在不同网络包长度和不同传输数据率下的PTP性能,分析了非PTP设备对传输精度的影响并进行了修正,将PTP协议在实际网络传输系统中的精度提高到了亚微秒级,为采用PTP协议的对时机制研究提供了参考。展开更多
Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for conne...Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byfine-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is significantly reduced and it outperforms the standard WiMAX preamble.展开更多
文摘随着以太网数据传输技术的广泛应用,数据传输速率不断地提升,传统的对时技术难以满足现代通信系统中实时传输的精度需求,网络业界提出了精密时钟同步协议标准(IEEE Standard for a Precision Clock Synchronization Protocol,IEEE1588),该标准采用精密时钟同步协议(Precision Time Protocol,PTP),精度可达微秒级。针对网络传输实时性的需求,阐述了PTP协议原理,通过搭建试验平台测试了在不同网络包长度和不同传输数据率下的PTP性能,分析了非PTP设备对传输精度的影响并进行了修正,将PTP协议在实际网络传输系统中的精度提高到了亚微秒级,为采用PTP协议的对时机制研究提供了参考。
文摘Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byfine-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is significantly reduced and it outperforms the standard WiMAX preamble.
