This paper addresses the performance of fast doubly selective fading channel estimation combined with InterCarrier Interference (ICI) cancellation for Long Term Evolution (LTE) communication platform in the High Speed...This paper addresses the performance of fast doubly selective fading channel estimation combined with InterCarrier Interference (ICI) cancellation for Long Term Evolution (LTE) communication platform in the High Speed Railway (HSR) environment. We consider the Channel Impulse Response (CIR) coefficients with a critical Doppler frequency shift and multi-path fading that were taken from the WINNER II channel model and the D2a propagation scenario, where the conditions of HSR are analyzed. As multi-path fading increases and the channel varies in the order of the symbol period, we first propose a novel approach for designing a pilot symbol structure in the time domain. Then, we describe the deployment of the proposed pilot symbol structure to estimate the channel in the time domain. Channel information corresponding to the data positions is obtained by linear interpolation. In each OFDM symbol, the slope and the initial value for establishing an interpolation function are estimated to adapt to the time variation of the channel. An accurate estimate of channel state information is used for the purpose of ICI cancellation. The simulation results show that the channel estimated by our proposed method can follow the real channel well, even in a very high Doppler frequency. The estimation method in terms of Mean Squared Error (MSE) significantly outperforms the state-of-the-art methods. The combination of our channel estimator with several interference cancelers provides a considerably better system performance than that achieved when frequency channel estimation is used.展开更多
随着高速铁路的快速发展,铁路无线通信系统对高可靠性、低时延、大带宽提出更高要求。通过分析传统铁路综合数字移动通信系统(Global System for Mobile Communications–Railway,GSM-R)的技术瓶颈,研究铁路长期演进(Long Term Evolutio...随着高速铁路的快速发展,铁路无线通信系统对高可靠性、低时延、大带宽提出更高要求。通过分析传统铁路综合数字移动通信系统(Global System for Mobile Communications–Railway,GSM-R)的技术瓶颈,研究铁路长期演进(Long Term Evolution for Railways,LTE-R)网络架构、业务模型与接入网冗余组网的优化方案,提出基于LTE-R技术的铁路无线通信系统优化策略。最后,通过实际测试与对比实验,验证LTE-R技术在信号覆盖、时延、吞吐量以及切换性能方面的优势,为铁路无线通信系统的升级与智能化提供理论支撑。展开更多
现有的针对高速铁路机车通信的信息集成方法效果并不理想,为此,文章提出基于铁路长期演进(Long Term Evolution for Railway,LTE-R)网络的高速铁路机车通信信息集成方法。基于LTE-R技术构建高速铁路机车通信信息集成模型,结合LTE-R网络...现有的针对高速铁路机车通信的信息集成方法效果并不理想,为此,文章提出基于铁路长期演进(Long Term Evolution for Railway,LTE-R)网络的高速铁路机车通信信息集成方法。基于LTE-R技术构建高速铁路机车通信信息集成模型,结合LTE-R网络算法提取高速铁路机车通信信息,采用Revit软件和收集器收集数据,实现高速铁路机车通信信息的统计与集成。实验结果证明,文章设计的基于LTE-R网络的高速铁路机车通信信息集成方法,对高速铁路机车通信信息集成的自动化程度较高,可节省99.99%的时间,具有较好的应用性能。展开更多
高速铁路隧道环境中采用LTE-R(long term evolution-railway)无线通信位置指纹定位解算时,针对加权K值邻近位置指纹解算精度低的问题,利用混沌粒子群算法优化权值的良好性能,提出基于混沌粒子群优化的加权K值邻近算法对列车位置指纹定...高速铁路隧道环境中采用LTE-R(long term evolution-railway)无线通信位置指纹定位解算时,针对加权K值邻近位置指纹解算精度低的问题,利用混沌粒子群算法优化权值的良好性能,提出基于混沌粒子群优化的加权K值邻近算法对列车位置指纹定位在线阶段进行指纹匹配解算,分别讨论了指纹间距取25 m、50 m、100 m时混沌粒子群优化加权K值邻近算法的收敛性和精确性.仿真结果表明:经混沌粒子群优化的加权K值邻近算法收敛速度更快,定位解算结果精度更高;在提高列车位置指纹定位精度方面,比单纯的加权K值邻近算法以及经粒子群优化的加权K值邻近算法更具优越性,当指纹间距取25 m时,列车定位误差小于25 m的概率高达96%,使隧道环境中列车位置指纹定位精度得到有效改善.展开更多
传统的基于长期演进的铁路移动通信系统(long term evolution-railway,LTE-R)切换算法对切换参数的选择不能很好地适应列车的高速移动,由此导致的"切换滞后"现象容易造成更多的失败切换,影响列车运行控制和旅客无线通信体验...传统的基于长期演进的铁路移动通信系统(long term evolution-railway,LTE-R)切换算法对切换参数的选择不能很好地适应列车的高速移动,由此导致的"切换滞后"现象容易造成更多的失败切换,影响列车运行控制和旅客无线通信体验。当列车高速穿越小区时,对越区切换的要求更加严格,简化信令流程以及实现快速切换是LTER急需解决的问题。以减少错误触发和实现快速切换为出发点,提出一种基于功率-距离的切换优化方案,充分考虑速度对切换参数的影响,并加入距离因素,只有当列车到达一定触发位置时才可以进行触发判断,如满足条件则直接进行切换。该算法在避免列车提前错误触发的同时舍弃触发时延(time to trigger,TTT)指标,在一个测量周期内即可实现快速切换。仿真结果表明,所提的方案能够更好地保证高速环境下列车的切换成功率。展开更多
高速列车在越区切换过程中,由于路径损耗和地形等因素的影响,参考信号接收功率(reference signal receiving power,RSRP)会发生上下波动,采用基于A3事件的传统越区切换判决方法,会导致发生乒乓切换和切换成功率下降。文中提出基于改进灰...高速列车在越区切换过程中,由于路径损耗和地形等因素的影响,参考信号接收功率(reference signal receiving power,RSRP)会发生上下波动,采用基于A3事件的传统越区切换判决方法,会导致发生乒乓切换和切换成功率下降。文中提出基于改进灰色-马尔可夫模型的切换算法,改进灰色-马尔可夫模型对参考信号接收功率进行处理和预测,结合预承载方法,利用处理结果作为切换判决依据执行切换过程。仿真结果表明,采用改进切换算法,使列车接收到的源小区和目标小区RSRP值的波动情况得到明显改善,乒乓切换概率更低,切换成功率得以有效提高。展开更多
文摘This paper addresses the performance of fast doubly selective fading channel estimation combined with InterCarrier Interference (ICI) cancellation for Long Term Evolution (LTE) communication platform in the High Speed Railway (HSR) environment. We consider the Channel Impulse Response (CIR) coefficients with a critical Doppler frequency shift and multi-path fading that were taken from the WINNER II channel model and the D2a propagation scenario, where the conditions of HSR are analyzed. As multi-path fading increases and the channel varies in the order of the symbol period, we first propose a novel approach for designing a pilot symbol structure in the time domain. Then, we describe the deployment of the proposed pilot symbol structure to estimate the channel in the time domain. Channel information corresponding to the data positions is obtained by linear interpolation. In each OFDM symbol, the slope and the initial value for establishing an interpolation function are estimated to adapt to the time variation of the channel. An accurate estimate of channel state information is used for the purpose of ICI cancellation. The simulation results show that the channel estimated by our proposed method can follow the real channel well, even in a very high Doppler frequency. The estimation method in terms of Mean Squared Error (MSE) significantly outperforms the state-of-the-art methods. The combination of our channel estimator with several interference cancelers provides a considerably better system performance than that achieved when frequency channel estimation is used.
文摘随着高速铁路的快速发展,铁路无线通信系统对高可靠性、低时延、大带宽提出更高要求。通过分析传统铁路综合数字移动通信系统(Global System for Mobile Communications–Railway,GSM-R)的技术瓶颈,研究铁路长期演进(Long Term Evolution for Railways,LTE-R)网络架构、业务模型与接入网冗余组网的优化方案,提出基于LTE-R技术的铁路无线通信系统优化策略。最后,通过实际测试与对比实验,验证LTE-R技术在信号覆盖、时延、吞吐量以及切换性能方面的优势,为铁路无线通信系统的升级与智能化提供理论支撑。
文摘现有的针对高速铁路机车通信的信息集成方法效果并不理想,为此,文章提出基于铁路长期演进(Long Term Evolution for Railway,LTE-R)网络的高速铁路机车通信信息集成方法。基于LTE-R技术构建高速铁路机车通信信息集成模型,结合LTE-R网络算法提取高速铁路机车通信信息,采用Revit软件和收集器收集数据,实现高速铁路机车通信信息的统计与集成。实验结果证明,文章设计的基于LTE-R网络的高速铁路机车通信信息集成方法,对高速铁路机车通信信息集成的自动化程度较高,可节省99.99%的时间,具有较好的应用性能。
文摘传统的基于长期演进的铁路移动通信系统(long term evolution-railway,LTE-R)切换算法对切换参数的选择不能很好地适应列车的高速移动,由此导致的"切换滞后"现象容易造成更多的失败切换,影响列车运行控制和旅客无线通信体验。当列车高速穿越小区时,对越区切换的要求更加严格,简化信令流程以及实现快速切换是LTER急需解决的问题。以减少错误触发和实现快速切换为出发点,提出一种基于功率-距离的切换优化方案,充分考虑速度对切换参数的影响,并加入距离因素,只有当列车到达一定触发位置时才可以进行触发判断,如满足条件则直接进行切换。该算法在避免列车提前错误触发的同时舍弃触发时延(time to trigger,TTT)指标,在一个测量周期内即可实现快速切换。仿真结果表明,所提的方案能够更好地保证高速环境下列车的切换成功率。
文摘高速列车在越区切换过程中,由于路径损耗和地形等因素的影响,参考信号接收功率(reference signal receiving power,RSRP)会发生上下波动,采用基于A3事件的传统越区切换判决方法,会导致发生乒乓切换和切换成功率下降。文中提出基于改进灰色-马尔可夫模型的切换算法,改进灰色-马尔可夫模型对参考信号接收功率进行处理和预测,结合预承载方法,利用处理结果作为切换判决依据执行切换过程。仿真结果表明,采用改进切换算法,使列车接收到的源小区和目标小区RSRP值的波动情况得到明显改善,乒乓切换概率更低,切换成功率得以有效提高。
