Various embodiments of a compact optical proximity sensor with a ball grid array and windowed or apertured substrate are disclosed. A number of routers are connected to the gateway and a number of wireless access networks are connected respectively to the routers for establishing wireless links with mobile stations. The chip comprises a substrate and a light emitting part constituted by an n-type GaN film, an active layer and a p-type GaN film successively laminated on the substrate. The fail condition in the AFR ratio sensor is determined based on the dead time TA and the response time TB. The identified code sequence in the object file is replaced with the replacement code sequence that includes a no-operation instruction or having fewer instructions than the identified code sequence. The control system includes a first module that estimates a damping force based on an assist torque and a handwheel velocity.