Research On The Access Mechanism For The Wireless Self-Organization Network With High Mobility

With the prosperity and development of wireless communication technology,various new network and communication technologies have emerged and showed strong vitality.Among these technologies,wireless self-organization network can be applied in the infrastructure-free environment.The topology of a wireless self-organization network is built in a autonomous manner without the coordination of central control node.Each node has equal role of the network and the communication between any two nodes is implemented through multi-hop relay.However,the hidden node problem happens a lot in the network access process due to the lack of coordination problem by the central control node.The hidden node problem existing in the network access of wireless self-organization network is focused in this thesis.First of all,the hidden node problem is analyzed and modeled.Then,A modified packet retransmission process with a new reference signal is proposed to facilitate the proposed transmission power control algorithm based on the dynamic threshold and fuzzy distance inference.From the simulation results,we observe that the performance of the proposed algorithm is better than the traditional one even in the wireless self-organization network with dense node population.Additionally,we also analyzed the distance estimation error due the mobility and proposed an improved velocity estimation algorithm to reduce the distance error induced by the user's mobility and increase the adaptability of the proposed network access procedure in the high mobility wireless self-organization network.The proposed velocity estimation method utilized the minimum mean square error(MMSE)estimation method to estimate the frequency offset due to mobility and finally obtain the user's mobility with reduced influence of noise.By combing the proposed velocity estimation and network access procedure,the network access performance degradation induced by mobility is reduced.