The rising number of electronic control units （ECUs） in vehicles and the decreasing time to market have led to the need for advanced methods of calibration. A multi-ECU calibration system was developed based on the ...The rising number of electronic control units （ECUs） in vehicles and the decreasing time to market have led to the need for advanced methods of calibration. A multi-ECU calibration system was developed based on the explicit calibration protocol （XCP） and J1939 communication protocol to satisfy the need of calibrating multiple ECUs simultaneously. The messages in the controller area network （CAN） are defined in the J1939 protocol. Each CAN node can get its own calibration messages and information from other ECUs, and block other messages by qualifying the CAN messages with priority, source or destination address. The data field of the calibration message is designed with the XCP, with CAN acting as the transport layer. The calibration sessions are setup with the event-triggered XCP driver in the master node and the responding XCP driver in the slave nodes. Mirroring calibration variables from ROM to RAM enables the user to calibrate ECUs online. The application example shows that the multi-ECU calibration system can calibrate multiple ECUs simultaneously, and the main program can also accomplish its calculation and send commands to the actuators in time. By the multi-ECU calibration system, the calibration effort and time can be reduced and the variables in ECU can get a better match with the variables of other ECUs.展开更多
现有TCP协议的拥塞控制机制存在很多不足,XCP(eXplicit Control Protocol)协议采用显式反馈的方式有效地克服了这些缺陷。XCP协议能容忍数据流之间一定的RTT差异,但当这种差异超出一定范围时,XCP协议性能恶化,变得不稳定。通过分析XCP...现有TCP协议的拥塞控制机制存在很多不足,XCP(eXplicit Control Protocol)协议采用显式反馈的方式有效地克服了这些缺陷。XCP协议能容忍数据流之间一定的RTT差异,但当这种差异超出一定范围时,XCP协议性能恶化,变得不稳定。通过分析XCP协议路由控制周期与数据流RTT的关系,提出了一种控制周期根据RTT差异程度而自适应调整的方法,消除了系统振荡。仿真数据表明,该方法能有效地提高XCP协议在数据流RTT差异较大的环境下的鲁棒性,同时不给路由器带来过大的计算负担。展开更多
在无线局域网络中,针对无线信道的异构性和传输控制协议(transmission control protocol,TCP)闭环拥塞控制的贪婪性,提出了一种基于显式拥塞通告(explicit congestion notification,ECN)标记算法的公平拥塞控制机制(access point conges...在无线局域网络中,针对无线信道的异构性和传输控制协议(transmission control protocol,TCP)闭环拥塞控制的贪婪性,提出了一种基于显式拥塞通告(explicit congestion notification,ECN)标记算法的公平拥塞控制机制(access point congestion control,APCC)。APCC在AP节点结合缓存队列长度和无线信道负载的测量来检测拥塞,依据联合的拥塞测度来实施拥塞控制,通过保证低丢包率和低排队延时得到了高吞吐率;利用ECN显式反馈机制,对通过AP的上行和下行TCP DATA和ACK分组实施ECN标记,实现了上下行公平的双向拥塞控制;同时在多速率信道环境下,依据各流的无线信道速率来调节单流ECN的标记概率,实现不同无线信道速率TCP流之间的时间公平,大大提高了网络的总体效率。展开更多
文摘The rising number of electronic control units （ECUs） in vehicles and the decreasing time to market have led to the need for advanced methods of calibration. A multi-ECU calibration system was developed based on the explicit calibration protocol （XCP） and J1939 communication protocol to satisfy the need of calibrating multiple ECUs simultaneously. The messages in the controller area network （CAN） are defined in the J1939 protocol. Each CAN node can get its own calibration messages and information from other ECUs, and block other messages by qualifying the CAN messages with priority, source or destination address. The data field of the calibration message is designed with the XCP, with CAN acting as the transport layer. The calibration sessions are setup with the event-triggered XCP driver in the master node and the responding XCP driver in the slave nodes. Mirroring calibration variables from ROM to RAM enables the user to calibrate ECUs online. The application example shows that the multi-ECU calibration system can calibrate multiple ECUs simultaneously, and the main program can also accomplish its calculation and send commands to the actuators in time. By the multi-ECU calibration system, the calibration effort and time can be reduced and the variables in ECU can get a better match with the variables of other ECUs.
文摘现有TCP协议的拥塞控制机制存在很多不足,XCP(eXplicit Control Protocol)协议采用显式反馈的方式有效地克服了这些缺陷。XCP协议能容忍数据流之间一定的RTT差异,但当这种差异超出一定范围时,XCP协议性能恶化,变得不稳定。通过分析XCP协议路由控制周期与数据流RTT的关系,提出了一种控制周期根据RTT差异程度而自适应调整的方法,消除了系统振荡。仿真数据表明,该方法能有效地提高XCP协议在数据流RTT差异较大的环境下的鲁棒性,同时不给路由器带来过大的计算负担。
文摘在无线局域网络中,针对无线信道的异构性和传输控制协议(transmission control protocol,TCP)闭环拥塞控制的贪婪性,提出了一种基于显式拥塞通告(explicit congestion notification,ECN)标记算法的公平拥塞控制机制(access point congestion control,APCC)。APCC在AP节点结合缓存队列长度和无线信道负载的测量来检测拥塞,依据联合的拥塞测度来实施拥塞控制,通过保证低丢包率和低排队延时得到了高吞吐率;利用ECN显式反馈机制,对通过AP的上行和下行TCP DATA和ACK分组实施ECN标记,实现了上下行公平的双向拥塞控制;同时在多速率信道环境下,依据各流的无线信道速率来调节单流ECN的标记概率,实现不同无线信道速率TCP流之间的时间公平,大大提高了网络的总体效率。
