Estimate of the high speed Wi-Fi handover

• Main Authors: Chung-Wen Jian, 簡聰文
• Other Authors: Dr.Yih G. Jan
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/29007891907062034158

碩士 === 淡江大學 === 電機工程學系碩士在職專班 === 99 === The wireless network, which made 802.11 at frequency of 2.4 GHz and 5 GHz and it was from ISM ( Industrial Scientific Medical )band, originated from IEEE (Institute of Electrical and Electronics Engineers ).With CAMA/CA mechanism, the transfer rate can reach up to 2 Mbit/s, and the speed of the wireless network increase constantly; it is able to meet the general application in our daily life. At present, the newest 802.11n wireless network can the transfer rate reach to the largest amount of 600Mbit/s, and it is quite beyond the general use in the surrounding area of our existence life. IEEE802.11Wireless Local Area Network has already held in and entered the daily life of everybody, but still it is limited at home or office use. This thesis will penetrate into other aspects of our life, such as having the transportation by moving vehicle, or extending communication network by applying wireless devices, and those will be expected to bring us a better life as well. If Wi-Fi can transmit data by a steady and high rate, it could replace WiMAX in many applications, especially in transportation. Once it can overcome the connection problem of roaming while vehicles are moving fast, the users will not experience connection breaks, and link quality can be accepted by the masses. The conveniences they bring are expected by us. The key to the whole wireless communication structure of transportation, The depends on the speed of HO (Handover) in BS. How to speed up HO and making users feel imperceptible any breaks of connection are the problems to be solved. They are several methods, such as using RSSI (Receiver Signal Strength Indicate) of received power to cut movements ahead of time, or adjusting the detect timing of RSSI to find the suitable timing for accelerating the whole roaming process. They can minimize the judgment time of HO, and they are better for some applications, like in High Speed Railway, or highway. There is an opportunity for all of these application to be improved through software; moreover, we can extend applications by letting this wireless communication structure to be used on carriages.