As one of the fastest growing wireless access technologies, wireless LANs must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordina...As one of the fastest growing wireless access technologies, wireless LANs must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordination Function （DCF） lack this ability. Work is in progress to define an enhanced version capable of supporting QoS for multimedia traffic at the MAC layer. In this paper, we aim at gaining insight into three mechanisms to differentiate among traffic categories, i.e., differentiating the minimum contention window size, the Inter-Frame Spacing （IFS）, and the length of the packet payload according to the priority of different traffic categories. We propose an analysis model to compute the throughput and packet transmission delays. In addition, we derive approximations to obtain simpler but more meaningful relationships among different parameters. Comparisons with discrete-event simulation results show that good accuracy of performance evaluation can be achieved by using the proposed analysis model.展开更多
Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solv...Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solved by the specifications export, this paper proposed a MAC frame analytical method and a PHY protocol type detection algorithm based on parsing the IEEE 802.11packets captured by the library Libpcap. The packet structure and the length of the frame preamble (18 or 26 bytes) are presented. Then the methods of transforming byte-order and resolving sub-fields are given. A detection algorithm of PHY protocol type is proposed based on the experiments and examples are given to verify these methods. This work can be a reference for the R & D related to link layer frame analysis.展开更多
The implementation method of the IEEE 802.11 Medium Access Control (MAC) protocol is mainly based on DSP (Digital Signal Processor)/ ARM (Advanced Reduced instruction set computer Machine) processor or DSP/ARM IP (Int...The implementation method of the IEEE 802.11 Medium Access Control (MAC) protocol is mainly based on DSP (Digital Signal Processor)/ ARM (Advanced Reduced instruction set computer Machine) processor or DSP/ARM IP (Intellectual Property) core. This paper presents a method based on Nios II soft-core processor embedded in Altera’s Cyclone FPGA (Field Programmable Gate Array) and MicroC/OS-II RTOS (Real-Time Operation System). The benefits and drawbacks of above methods are compared, and then the method presented in this paper is described. The hardware and software partitioning are discussed; the hardware architecture is also illustrated and the MAC software programming is described in detail. The presented method has some advantages, such as low cost, easy-implementation and very suitable for the implementation of IEEE 802.11 MAC in research stage.展开更多
基金Supported in part by the National Natural Science Foundation of China (Grant No. 60572144)the Natural Science Foundation of Shaanxi Prov-ince (Grant No. 2005F27)+1 种基金the Chinese Government Program for New Century Excellent Talents in University (Grant No. NCET-06-0876)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, and the Youth Science and Technology Innovation Foundation of NPU (Grant No. W016207)
文摘As one of the fastest growing wireless access technologies, wireless LANs must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordination Function （DCF） lack this ability. Work is in progress to define an enhanced version capable of supporting QoS for multimedia traffic at the MAC layer. In this paper, we aim at gaining insight into three mechanisms to differentiate among traffic categories, i.e., differentiating the minimum contention window size, the Inter-Frame Spacing （IFS）, and the length of the packet payload according to the priority of different traffic categories. We propose an analysis model to compute the throughput and packet transmission delays. In addition, we derive approximations to obtain simpler but more meaningful relationships among different parameters. Comparisons with discrete-event simulation results show that good accuracy of performance evaluation can be achieved by using the proposed analysis model.
文摘Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solved by the specifications export, this paper proposed a MAC frame analytical method and a PHY protocol type detection algorithm based on parsing the IEEE 802.11packets captured by the library Libpcap. The packet structure and the length of the frame preamble (18 or 26 bytes) are presented. Then the methods of transforming byte-order and resolving sub-fields are given. A detection algorithm of PHY protocol type is proposed based on the experiments and examples are given to verify these methods. This work can be a reference for the R & D related to link layer frame analysis.
文摘The implementation method of the IEEE 802.11 Medium Access Control (MAC) protocol is mainly based on DSP (Digital Signal Processor)/ ARM (Advanced Reduced instruction set computer Machine) processor or DSP/ARM IP (Intellectual Property) core. This paper presents a method based on Nios II soft-core processor embedded in Altera’s Cyclone FPGA (Field Programmable Gate Array) and MicroC/OS-II RTOS (Real-Time Operation System). The benefits and drawbacks of above methods are compared, and then the method presented in this paper is described. The hardware and software partitioning are discussed; the hardware architecture is also illustrated and the MAC software programming is described in detail. The presented method has some advantages, such as low cost, easy-implementation and very suitable for the implementation of IEEE 802.11 MAC in research stage.
