A divided Media Access Control (MAC) protocol structure, a data transmission and reception method, and a handover method and system using the structure in a wireless communication system for efficiently managing session information in handover of an MSS (Mobile Subscriber Station). In the MAC protocol structure, a MAC is divided into a MAC-high layer and a MAC-low layer. The MAC-high layer performs session information-related functions and the MAC-low layer performs functions sensitive to a time delay in relation to handover of an MSS. In the handover method, when an MSS in the wireless communication system performs handover between Access Points (APs), session information is managed at a fixed position by an Access Point Controller (APC) including an MAC-high layer or a serving AP. Therefore, the system load can be reduced and communication quality can be improved.