Research On Network Coding Of Data Distribution In Mobile P2P Networks

Since the continuous improvement of hardware design level and production capacity,it greatly increases the portability and capacity of storage and calculation of mobile terminal equipment,along with the development of wireless communication technology,a variety of wireless network are prompted and are used more and more widely in various fields.With the popularity of wireless network applications and the increasing demand of data distribution,P2P data distributed technology is applied to the mobile network,and the concept of mobile P2P network arises at the historic moment.Due to the complexity of the composition of mobile P2P network,make it have three obvious characteristics of limited node energy,network topology changeable and the heterogeneity of underlying network.The existing P2P data distributed technology cannot play their advantages based on the three characteristics of mobile P2P network,so it is necessary to research the data distribution technology point to the characteristics of mobile P2P network.Using multicast technology in data distribution,data is transmitted along the multicast tree and can be sent to multiple nodes at the same time,so the number of forwarding is reduced by the multicast technology.The application of network coding in the multicast network improves the efficiency of data distribution,and makes the multicast rate reach the maximum flow of the network.Network coding on one hand can play the advantages of multicast,on the other hand,network coding can make full use of the radio characteristics of wireless channel in mobile P2P network data distribution.Network coding brings many benefits to mobile P2P network data distribution,but also creates some new problems,such as the large amount of calculation in node encoding process,the waiting in encoding process,and the low overall utilization of network resources.On the basis of the existing researches,this paper has mainly researched the three important factors of the calculation of encoding nodes,the waiting time of encoding,and the utilization of channel resource that affect the data distribution system performance intensive.The concrete research content is as follows:(1)In existing methods of optimizing encoding process,the research is mainly progressed from the three aspects of the partial coding vector,the running time of cache system and the quantity of the data,but it doesn't consider the encoding process optimization from the data constitution itself,so data selection is not accurate enough.For this kind of situation,it is proposed that a minimal increasing network coding based on the non-zero components constitution of global coding vector.In this paper,it combines global coding vector and the information of non-zero component,adds the non-zero component instruction set into the packet,and makes the node select the data blocks for encoding by the indicator set of non-zero components.The experimental results show that the method can effectively reduce the calculation of node in encoding process,thus it can reduce the node energy consumption of coding,and at the same time shorten the process performed by coding time.(2)The topology of mobile P2P network is changeful,and the channel resource is scarce.In existing network coding schemes,the states of encoding mode transform linearly,so there is a problem of coding waiting in mobile P2P network which wastes channel resources.Aiming at this problem,this paper proposes a multiple network coding of feedback control based on the relationship of the data demand and the amount of data reception in nodes.In different topology,node needs to transmit the data to the neighbors in different times to meet their requests,the module state of transformation process can be simplified according to the data demand information of neighbor nodes.Experimental results show that the proposed feedback of network coding of multiple can adjust the code number to avoid waiting,at the same time it can improve the data distribution rate in mobile P2P network.(3)The underlying network of mobile P2P has obvious heterogeneity,although network coding can improve the network transmission efficiency for single rate multicast,but still can't solve fairness problem of nodes with different computing power and of communication ability.Aiming at this problem,it is proposed that a multi-rate network coding of multi-generation mixing in this this paper.There is a same characteristic of containing the lower level date in multi-rate multicast and the multi-generation mixing network coding,and the two technologies can be combined under the rate allocation scheme.The experimental results show that the multi-rate network coding of multi-generation mixing can improve the max-flow rate in data distribution.The dissertation presents the improvement schemes to the deficiencies of network coding used in data distribution of mobile P2P environment,the proposed schemes reduce the computation of node coding process and the number of data forwarding,and increase the efficiency of channel resource on the premise of guarantee to improve the transmission performance of network.