Research On Wireless Token Network With Sub-Nodes Protocol For Wireless Ad Hoc Network

Ad Hoc network, which has characteristics of no center, self-organization, supporting dynamic topology and robustness, is a kind of wireless local area network. It has wide use in the field of aviation communications, emergency communications, remote areas of communication, and even home wireless network and mobile medical monitoring system. This paper analyses several representative MAC protocol for Ad Hoc network and focuses on wireless token ring protocol. The Wireless Token Ring Protocol (WTRP) is a distributed medium access control (MAC) protocol which features self-organization, self-healing and no center, etc. It also guarantees fair node access and quality of service (QoS). It is proved to be a valuable MAC protocol candidate for wireless sensor networks with relatively stable structure. But due to the enclosed nature of the ring structure, WTRP is not suitable for scenarios with rapid topology variations.To solve above issues, this paper presents a modified protocol called Wireless Token Network with Sub-nodes Protocol(WTNSP)with describing its network architecture, structure of MAC frame, network establishment and maintenance, etc. WTNSP defines sub-nodes which only have predecessor but no successor. In order to ensure token network, WTNSP adds token frame and improves joining/leaving mechanism for sub-nodes. The modified node joining mechanism expands the closed loop into net with sub-nodes, which enables better coverage and higher moving speed; while dynamic token hold time adjusting enhances data throughput. Besides, the modified protocol effectively reduces establishment time through specifying that only building basic token network without sending data information at the very beginning. The author makes experiments to demonstrate that the performance both of throughout and network coverage of WTNSP is better than WTRP.WTNSP is suit for the environment which needs both no center network communication and rapidly changing of network topology. In view of the application, this paper designs High-speed Wireless Data Collaboration System (HWDCS), which using an orthogonal frequency division multiplexing (OFDM) as the core modulation technique, solving the signal distortion problem caused by multipath interference, shadow, fading, noise, and the Doppler effect in the wireless environment, and supporting point to point communication or wireless ad hoc network communication at speed of180km/h.This paper makes experiments to analysis and verifies the performance of high-speed wireless data collaboration system, including system RF performance, system communication range, the maximum rate of movement, environmental adaptability and so on. Verified through laboratory and road tests, the high-speed wireless data collaboration system can work properly in the range of-45℃to70℃. Its bandwidth shoulder ratio is about-57.67dB, bandwidth external suppression ratio is about-54.19dB. The system can support telecommunication range of9.8km with10W amplifier and can support node moving speed of180km/h.