Methods and apparatus for efficient two-stage paging wireless communications systems are described. The invention includes multi-level coding in which data is partitioned between two encoders, one for encoding Most Significant Bits and the other for encoding Least Significant Bits. The carrier particles contain a binder resin and magnetic metal oxide and have shape factors SF-1 of 100 to 150 and SF-2 of 100 to 150. The lane detecting device detects the running lane based on a variation in a running direction of the vehicle due to the yaw moment generated by the vehicle behavior control device.