The Study And Implementation Of Entry Process For Subscriber Station Of Fixed Broadband Wireless Access Network Based On IEEE802.16

The access technology is one of the hot topics of current communication field. As the development direction of the broadband access technology, FBWA(Fixed broadband wireless access)draws people's attention widely. The application, development and prospect of the Access Network are discussed in this paper first. And the advantage, history, development of FBWA technology are also introduced. Then the system constitute and the protocol layer architecture of the IEEE 802.16 protocol are discussed. And some important parts of the protocol, such as physical layer and common part sublayer, are analyzed and studied completely. Meanwhile the software frame of 802.16 system is presented and partitioned to some function modules.Based above statement, the entry process for subscriber station of IEEE802.16 is particularly analyzed and studied in this paper. The entry process is partitioned to nine sub processes in implementation as scanning and synchronization to the downlink, obtain downlink parameters, initial ranging and automatic adjustments, negotiate basic capabilities, authorization and key exchange, registration, establish time of day. transfer operational parameters. The realization of the entry process is designed as keeping the state machine running and making the entry state transfer. Every sub process is also analyzed in detail and the concrete implementation flow of sub processes is designed in this article.At the end of the paper, the random access in the entry process is studied comprehensively. The contention resolution arithmetic for random access is introduced firstly. And the shortage of the contention resolution arithmetic in 802.16 is analyzed. Then the resolution is improved. A new contention resolution arithmetic, the start backoff window can be regulated by base station according to the number of subscriber station, is proposed. Lastly, the computer emulation waveform of both arithmetic is presented and the results prove the new arithmetic can reduce the delay of the entry process.