The Investigation Of New Handover Algorithm In OFDMA System

With the development of mobile communications, people request more and more broad-band traffic. Mobile communication systems in future(such as Beyond 3G and 4G)must support higher transmitting ability. Among many division access technologies, OFDMA(Orthogonal Frequency Division Multiplex access) is best. OFDMA system transforms high-speed serial data streams to low-speed parallel data sub-channels and transmits them. It can well solve frequency-selective fading and effectively deal with ISI(inter symbol interference) in broad-band wireless condition, it can utilize channel fading characteristics and frequency diversity gain, and improve system's capability.At first this text introduces OFDMA system theory sub-carrier allocation scheme and radio resource management(RRM) technologies; and then researches OFDMA system's handover technology deeply, analyses and concludes the disadvantages of present handover algorithms.Based on OFDMA system, considering the disadvantages of present handover algorithms, this text puts forward new OFDMA handover algorithms: Level-up handover and sub-carrier borrowing handover. The former can ensure that handover user obtain better channel quality, cooperating with self-adaptive modulation technology, it can enhance OFDMA system's throughput. The latter not only has the advantages above but aslo makes full use of OFDMA channel resource, improves channel uslizing effectivity and flexibility.After theoretic analysis, the author designs OFDMA system level simulating platform. By simulating, the author compares the Level-up handover algorithm with Proposed handover algorithm. Simulating result proves that new handover algorithm can guarantee the handover users' sub-carrier channel quality, and improve OFDMA system throughput and optimize system performance.