REGISTRATION METHOD, DEVICE AND SYSTEM

Embodiments of the present invention disclose a terminal device registration method and a device. The method includes: sending upstream registration window information to a terminal device, where the upstream registration window information is used to indicate a starting position of an upstream registration window to the terminal device; receiving an upstream access signal sent by the terminal device from the starting position of the upstream registration window, where the upstream access signal includes a correlation sequence symbol and at least one OFDM symbol following the correlation sequence symbol, the correlation sequence symbol is constituted by a first sequence that meets a preset condition, and the at least one OFDM symbol is used to modulate access information by means of differential phase modulation in a frequency domain; and performing upstream ranging according to the starting position of the upstream registration window and the correlation sequence symbol, so as to obtain an upstream ranging result. In the embodiments of the present invention, upstream registration and upstream ranging can be implemented in an OFDM PON system.