This paper proposes an optical access networks that guaranteed QoS in bidirections. Our scheme is the PON (Passive Optical Network) systems using OCDM (Optical Code Division Multiplexing) technology. For the bidirectional 100 Mbps guaranteed, we examined the simple decision circuit, code length (the number of chips), the number of simultaneously accesses and transmission distance. Furthermore, we reported the results that evaluated prototype of speed-down (4 Mbps, 16 chips) for the functional check of simple decision circuit.