Cooperative MAC Protocol In Dense WLAN

How to design effective wireless cooperative MAC protocol to effectively improve network performance is a hotspot in the research of wireless cooperative communication.Most researchers design cooperative MAC protocols from the aspects of algorithm design,cross-layer design,and other technologies.However,there are few researches on intensive network scenarios in MAC protocol,especially the problem of hidden terminals has a serious impact on the performance of cooperative MAC protocol.It needs to design a good cooperative MAC protocol in a simple way to improve the network performance and reduce the probability.In addition,there are many researches on the selection of relay nodes,but there is a lack of factors such as instantaneous channel state and node energy.And some relay selection algorithms introduce complex frame switching process,which makes cooperative MAC protocol complicated.And resource reservation scheme provides a new way to reduce conflicts of dense wireless network.If it can be combined with cooperative MAC protocol,it will be of great significance to improve the network performance.Aiming at the shortcomings of these studies,the main contents are as follows:(1)The hidden terminal problem is modeled and analyzed,and the thesis proposed cooperative MAC protocol which converged random linear network coding.In the thesis,it uses the random linear network coding technology to encode the payload field.And the protocol uses the relay node to complete the cooperative communication,puts forward the request relay frame strategy,which can effectively deal with the repeated collision problem and improve network throughput.Finally,through theoretical analysis and experimental simulation,it is compared with other wireless MAC protocols to verify the impact of the proposed MAC protocol on network performance.At the same time,the factors,such as the size of the data packet,the number of data fragments and the data transmission rate,influences the performance of the protocol.The thesis analyzes the three factors on the performance of the network in order to achieve the purpose of maximizing the performance of the network.(2)A cooperative MAC protocol based on relay selection is proposed.In the thesis,the relay selection strategy is proposed which considering the channel state and the residual energy of the node without loss of throughput.According to the received signal strength and the random value obtained from the random range of different levels,only the neighboring nodes that meet the cooperative transmission conditions become the relay node to complete the cooperative communication.Finally,the simulation experiment of the protocol is carried out to verify the performance of the protocol in extending the network lifetime.(3)The MAC protocol with joint resource reservation and collaboration is proposed in this thesis.Resource reservation schemes provide new ideas for the reduction of conflicts in dense wireless networks.And Collaborative transmission scheme is an important means to improve network performance.This thesis combines time reservation,spatial reservation with collaborative transmission scheme to improve the network performance.In order to balance the effects of spatial reuse and interference,the thesis optimize the spatial reservation size.Finally,the experimental results show that the proposed MAC protocol can improve the performance of the network.