Wireless LAN network, and mobile station, base station and method of controlling handoff in wireless LAN network to prevent packet loss during handoff

A method of controlling handoff in a wireless local area network (LAN) network, comprising:

• notifying, by a mobile station, a first base station of a first entry into a power-save mode;
• buffering, in the first base station, a first packet to be transmitted to the mobile station through the first base station;
• performing, at the mobile station, a handoff initiation process with a second base station to which the mobile station performs handoff;
• notifying, by the mobile station, the first base station of a first exit from the power-save mode;
• transmitting the first packet from the first base station to the mobile station;
• notifying, by the mobile station, the first base station of a second entry into the power-save mode;
• and
• establishing, by the mobile station, a handoff link with the second base station in response to notifying the first base station of the second entry into the power-save mode,
• wherein performing the handoff initiation process comprises:
• transmitting, by the mobile station to the second base station, a probe request message after notifying the first base station of the first entry into the power-save mode;
• and
• receiving, by the mobile station from the second base station, a probe response message in response to the probe request message.

A base station in a wireless local area network (LAN) network, comprising:

• a packet determiner to determine whether a notification of an entry into or an exit from a power-save mode is received from a mobile station that is located in an area managed by the base station;
• a buffering controller to control a packet to be transmitted to the mobile station, the buffering controller to buffer the packet in response to the packet determiner being notified of the entry into the power-save mode by the mobile station;
• a releasing controller to release the buffered packet to the mobile station in response to the packet determiner being notified of the exit from the power-save mode by the mobile station;
• and
• a handoff controller to perform a handoff negotiation process with the mobile station after the mobile station transmits a message notifying entry of the mobile station into the power-save mode to another base station, and
• to perform a handoff link establishment process with the mobile station after the mobile station retransmits the message to the another base station,
• wherein the handoff negotiation process comprises receiving a request message from the mobile station, and
• transmitting a response message to the mobile station in response to the request message.

A mobile station in a wireless local area network (LAN) network, comprising:

• a handover controller to control a handoff process from a first base station connected to the mobile station, to a second base station, to which the mobile station performs handoff to;
• and
• a memory to store address information of the first base station, the second base station, and the mobile station,
• wherein the handover controller comprises:
• a scanning module to send a message notifying entry of the mobile station into a power-save mode to the first base station and to perform a scanning process to search for the second base station among base stations located around the mobile station;
• a probing module to send a probe request message to the second base station in response to the scanning module performing the scanning process, and to receive a probe response message from the second base station, after the message is sent;
• and
• a link establishment module to resend the message to the first base station and to establish a link with the second base station after resending the message.