Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handove...Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handover delay by making handover preparation before handover starts. Scheme B aims at reducing unnecessary handovers and improving handover success rate, by calculating the geographically best target handover cell, which makes it easier for mobile terminals to access the target cell. A system level simulation is conducted to evaluate the performance of these two schemes. It is shown that, scheme A could reduce inter-site handover delay by about 50 ms, while scheme B could cut down nearly 50% of all handovers when time-to-trigger （TTT） is 0 ms. Besides, as TTT gets larger, Scheme B has much better success rate.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
针对高速铁路LTE网络切换成功率未被充分提升的问题,提出一种基于位置信息与波束赋形辅助的切换算法.首先通过接收信号波达角(Direction of Arrival, DoA)和邻区列表快速锁定目标小区;然后将波束赋形引入高铁的切换重叠区,以产生不同的...针对高速铁路LTE网络切换成功率未被充分提升的问题,提出一种基于位置信息与波束赋形辅助的切换算法.首先通过接收信号波达角(Direction of Arrival, DoA)和邻区列表快速锁定目标小区;然后将波束赋形引入高铁的切换重叠区,以产生不同的波束赋形增益服务于不同的区域;最后计算出预触发起点位置和触发位置,并分别执行信道资源的预分配和触发判断任务.由实验结果表明,改进算法相比于传统切换算法和提前切换算法,在列车处于相同位置时有更高的切换成功率,可更好地适应高速铁路环境.展开更多
基金supported by the National Natural Science Foundation of China(No.61032002)the National Basic Research Program of China(973 Program No.2012CB316100)the 111 project(No.111-2-14)
文摘Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handover delay by making handover preparation before handover starts. Scheme B aims at reducing unnecessary handovers and improving handover success rate, by calculating the geographically best target handover cell, which makes it easier for mobile terminals to access the target cell. A system level simulation is conducted to evaluate the performance of these two schemes. It is shown that, scheme A could reduce inter-site handover delay by about 50 ms, while scheme B could cut down nearly 50% of all handovers when time-to-trigger （TTT） is 0 ms. Besides, as TTT gets larger, Scheme B has much better success rate.
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。
文摘针对高速铁路LTE网络切换成功率未被充分提升的问题,提出一种基于位置信息与波束赋形辅助的切换算法.首先通过接收信号波达角(Direction of Arrival, DoA)和邻区列表快速锁定目标小区;然后将波束赋形引入高铁的切换重叠区,以产生不同的波束赋形增益服务于不同的区域;最后计算出预触发起点位置和触发位置,并分别执行信道资源的预分配和触发判断任务.由实验结果表明,改进算法相比于传统切换算法和提前切换算法,在列车处于相同位置时有更高的切换成功率,可更好地适应高速铁路环境.
