Cross-layer Design For QoS Guarantee In Wireless Ad Hoc Networks

With rapid development and commercialization of current Internet multimedia business such as VoIP, video meeting etc and personal communication system becoming broadband, the application environment of wireless Ad Hoc network gradually extends from original military application to more civil fields. However, the connatural characteristics of wireless channels and the mobility of nodes, multi-hop spaces multiplexing methods and self-organizing characteristic make supporting QoS in wireless Ad hoc network face much more new challenges. Thus, research of QoS in wireless Ad Hoc network has very important practical meaning and applicable value. This paper starts from the researches of QoS architecture,QoS signaling ,different controlling strategies which supports operation differentiation and resource conservation and points out that QoS controlling strategies of different layers are independent from each other, part optimization and redundancy of multi layer repetition similarity controlling strategy limits the performance of wireless self-organized network.. It points out that vague boundary between layers and cross-layer design would be the trend of development of wireless network. Research of QoS should break through the independence between layers of traditional OSI architecture and improve the whole performance by joint optimization through transmitting controlling message in cross-layer architecture. It also provides practicable cross-layer QoS model. This paper digs into basic media access control protocol DCF and EDCF in IEEE 802.11 and 802.11e, and advances computing method of average back off window and theory analytical method of access delay for DCF and EDCF. And it validates the validity of computing method through simulation, and therefore provides theory basis for researches of real-time transmitting operations in wireless LAN. This paper restricts delay through cross-layer design. The cross-layer data channel model it advances combines cross-layer protocol design and DiffServ architecture, applies DCS-PDD cross-layer scheduling arithmetic in cross-layer QoS mapping model and admitting controlling model. And in link layer through using scheduling arithmetic based on delay feedback, it can accurately ensure peer-to-peer delay acquired by user operation. Aim at problems existed in wireless TCP, the ARQ CAE-TCP model that it advances and jointly used by TCP and link layer picks up ARQ information from link layer to generate affirmation to TCP data packets, decreases total ARQ times. And through adopting simulation in wireless LAN scenarios, it can be proved that CAE-TCP improves the throughput of TCP.