The Mobile Handover System Design And Algorithm Simulation For802.16e

At present, the wireless network has been widely applied to various aspects of society, and is developing to the direction of movable and high bandwidth. The802.16e standard-based wireless metropolitan area network technology has been concerned and quickly recognized for its high bandwidth and removable features. On the basis of the previous versions the standard802.16e adds movable properties, thus it becoming a strong competitor of the3G technology. The WiMAX technology can provide a broader coverage and higher transmission rates than WiFi. The WiMAX can be used for supplement to the existing communication technology to solve the last mile wireless access problems, and can be a separate network to provide users with telecommunication level network.The most significant features of the802.16e standard is the mobility, and the most important part of mobility management mechanism is the handover, so mobile handover mechanism will directly determine the pros and cons of the wireless network stability and quality of services. In this thesis, the handover in the802.16e protocol has been carefully studied, and efforts of this thesis as follow:(1) Learning more about the background of the802.16e protocol handover technology, the protocol frame structure and mode of operation, and then introduces the key technologies and technical advantages of this protocol.(2) Introduce the handover function model and network components of802.16e supported, and analyses the two different types of handovers, the soft handover and the hard handover. Soft handover is a smooth and continuous way of handover, and its effect is high, but waste network resources; Hard handover is a after the break to connect handover mode, It can make full use of wireless resources, but handover effects are relatively poor. When the quality requirements are not high on the network environment, the hard switching is a better choice.(3) Introduce the handover function module and the communication interface with other modules based on signal strength with the PC7203, PC7205development board of the PicoChip as base station and mobile terminal hardware development platform, and with Linux system of CentOS version as a software environment.The base station and mobile terminal handover module code is written in C. Finally, the handover function was achieved.(4) Research the existing handover algorithms are basically the signal strength as a reference volume, but the signal strength can not fully reflect the status of the channel, so this thesis puts forward to the Carrier to Interference plus Noise Ratio (CINR) as a reference volume. Then simulate this algorithm through the NS network simulation platform, because the NS does not support the corresponding module of the802.16e protocol, the design added NIST with WiMAX simulation module and modify corresponding class of this module. Finally, the simulation process finished. The simulation results show that the handover algorithm based on the Carrier to Interference plus Noise Ratio can improve the overall quality of the handover.