An anchor gateway, a communication method and a tangible machine-readable medium are provided. The anchor gateway is for use in a WiMAX network comprising an authentication gateway and a serving base station (BS). After a mobile station (MS) enters the WiMAX network, the anchor gateway will request the authentication gateway and the serving BS according to an identification of the MS to respectively provide authentication key context and medium access control context. Thereby, the network latency, which is made by the MS in handover, will be reduced effectively.