Efficient controller area network data compression for automobile apphcations

目的:控制器局域网CAN(controller area network)被设计作为汽车环境和高级工业控制应用中电子控制单元ECUs(electronic control units)之间的多路通讯。如果大量ECUs连接到CAN总线,会导致CAN总线陷入超载状态,待命时间和数据传输误差率也将增加。数据传输时间和帧长度成正比,因此需要减少CAN总线的数据帧长度。创新:与已有数据压缩方法相比,我们提出的方法不需要预测最大差值,只需使用三个头比特位。实验结果表明,CAN传输数据的压缩率高达81.06%。方法:首先,用信号重排方法将车辆技术标准中的信号重排,使数据帧内的信号缩短到三个。然后,计算之前和现在CAN信号差值,并且计算三个头比特位。将头比特和差值不为零的信号排列到压缩区域选择图里,不为零的区域选择为压缩区域。最后,将压缩区域的数据排列到2D内存图里(图5,6)。结论:针对CAN总线超载和数据传输误差率的增加,提出一种高效的数据压缩方法,数据压缩率高达81.06%。

Spectrum sensing using multiple dual polarization antennas for cognitive radio systems in microcell environments

Spectrum sensing with multiple antennas for cognitive radio systems in microcell environments is affected by the spatial correlation among multiple antennas.To reduce the adverse effects of the spatial correlation on the spectrum sensing performance,we employ multiple dual polarization antennas at the sensing node of secondary users.The analysis of the spatial correlation is derived using the propagation characteristics of the electromagnetic wave based on the scattering patch model in a multipath microcell environment.The superiority of spectrum sensing with multiple dual polarized antennas over multiple mono-polarized antennas is shown by analyzing the false alarm and detection probabilities with the correlation among the antennas in a microcell environment.