current researches

The status of current researches in terms of domestic and foreign handover technology based on the MAC layer in WLAN are analyzed and summarized. It is the brief introduction and evaluation of the selective scan algorithm (including Neighbor Graph algorithm, WSN algorithm), advanced scan algorithm, the authentication stage algorithm (including FHR prediction algorithm, Orientation algorithm, Neighbor Graph authentication algorithm), reassociation stage algorithm (including prediction algorithm, Neighbor Graph reassociation algorithm) and so on. The complete handover process is included three stages: channel scan, authentication and reassociation. especially the delay time of scan stage is about 90%, but authentication and reassociation are short, and it is compared with the WLAN and GSM's handover problems.2. Those algorithms concerning the various stages in the handover process based on neighbor graph technology are in summary unified for the Neighbor Graph algorithm series (NGAS), and is proposed to the technology synthetic unity to NGAS.3. The Mobile Station Orientation algorithm based on NG (MSO) is proposed in this dissertation, which is a quasi-minimum time delay's algorithm. According to apply to various users in WLAN environment with different density, structure and layout, three mechanisms to achieve the program are proposed, including selelcting the target AP based on the distance among neighbor APs, selelcting the target AP based on the movement direction and selelcting the target AP based on QoS protection.