The Next-generation Broadband Wireless Access Based On The The Ieee802.11 And Ieee802.16mac Layer Qos Mechanisms And Improvement

With the development of broadband transmission and the diverse business of the communication industry, broadband wireless is accessing a rapid growth. It makes establishing network flexible, upgrading and maintaining easy, and has the high-speed two-way data transmission as well as other advantages. So it obtains the favor of the communication industry, and the technology and service applications develop rapidly. As the technical transformation and the people's need of information technology growth, the broadband access showes a huge market. Some data show that wireless broadband access market will reach 10 billion dollars in next 5-10 years in the USA. In China, with the rapid development of Chinese telecommunications industry, broadband network construction is experiencing an unprecedented development. Chinese major communication carriers are focusing on building high-speed broadband data communications networks. No doubt that in response to the backbone network of the telecommunications carriers, the new round of competition will be the wireless broadband access.As the representative technology in WLAN and WMAN wireless broadband access, WiFi and WiMAX technologies develop and mature unceasingly, and their support to QoS improved. They impel the broadband wireless access technology development and progress, and stimulate the wireless access market growth.The WiFi alliance establishment is for the purpose of guaranteeing the different products the compatibility and the Interoperability. Today WiFi nearly has become the synonym with IEEE802.11 and WLAN. With this similar, the WiMAX also nearly has become the synonym with IEEE802.16.In recent years, the overture that WiFi and WiMAX replace 3G appeares frequently. WiFi and WiMAX have high access rate and flexible framework. To solve wireless broadband applications, they support mobile computing. The system construction costs is relatively lower and extension better, especially in the place where hot spots application useing wide. Recently there have been many places to take this item as a new luminescent spot in the communications applications.For network users, providing appropriate QoS guarantee is very important. Experts predicted that, the QoS guarantee degree of the broadband wireless access is the key to success in field of communications in the future.This dissertation researched the existing QoS mechanism of WiFi and WiMAX, and improved the legacy QoS mechanism. For the QoS mechanism of WiFi: First, based on the aim of guarantee the maximum tolerance delay, improved the EDCF, enhanced the video service performance under the high channel load in guarantee the high priority service in the foundation. Then, proposed a dynamic adaptive EDCF which introduced P factor which based on the channel condition to the channel access mechanism. It enhanced the QoS performance under the high channel load further, specially the medium and the low priority flows performance. Last, provided a theoretical model, which takes into account the effects of both collisions and transmission errors in a noisy channel, for EDCF-BTA scheme in the noisy channel based on the priority flow. And we analyzed and researched the performance of the EDCF-BTA scheme based on the theoretical model. For the QoS mechanism of WiMAX: this dissertation designed an improved Cross-Layer QoS scheduling architecture based on the existing QoS architecture of 802.16 standard, and specified every module in the improved QoS scheduling architecture.Last, an AP had been designed based on QoS guaranteer in WiMAX+WiFi network.