| With the real-time multimedia data traffic increasing,people require higher quality on bandwidth of network,performance,coverage and so on. Faced with these new challenges, wireless MAN based on IEEE 802.16 standard is widely favored by the market for economic,convenient,simple of operation and maintenance. By supporting mobility, IEEE 802.16 Standard has a very wide range of application of space and becomes a research focus in wireless broadband communications field.Handover which generates with the mobile station switching from one base station to another is a difficulty point in wireless broadband communications.Handover is one of the most important and complex processes in wireless broadband communications.It is responsible for maintaining the terminal device within the network of persistent connections, involving a number of information exchanges between base stations,mobile station and control center. Good or bad of handover directly affects service quality of system and user experience.First, this paper analyzes background,application fields and technical advantage of IEEE 802.16 Standard. This paper focuses on working principle of MAC (media access layer),network topology, protocol data unit, scan and handover. There are three kinds of handover: hard handover, Macro Diversity Handover, Fast Base Station Switching and hard handover is necessarily implemented according to the standard. Based on the above-mentioned study, hard handover is designed and implemented with the existing signal supplied by the standard. The paper solves judgments of scan and handoveranalyzes and solves two anomalies:handover dropping of service base station and handover dropping of target base stations.Last, this paper designs debugging scheme of system and handover process, analyzes results and gives suggestions on future improvement.Finally, by Summing up the previous work, this paper points out that the lack of current work and work plan of the next phase. |
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