A transmission drive system has two AC induction traction motors, each operatively coupled to two semi-independent coaxial traction shafts, and two AC induction steer motors coaxially mounted on a common steer axis parallel to the coaxial traction shafts. In an embodiment of the invention, a frame buffer for a interlaced display is filled. Service information of a subscriber is collected, and physical layer target parameters are obtained according to Quality of Experience parameters corresponding to the service information. The phase variation in the slab-select direction is, on the whole, large enough that the peak amplitude of the received signal is reduced and the signal width broadened.