Interference Coordination Mechanism For Wi-Fi And LTE-U Hererogeneous Networks

With the continuous development of wireless communication technology, the lack of wireless spectral resources becomes more and more obvious. Since LTE is gradually used in unlicensed bands, LTE-U (LTE in the unlicensed bands) is possible. However, the interference of LTE-U between Wi-Fi can not been ignored. Thus it becomes very important to study how to deal with this kind of interference. As is known to all, due to the heterogeneity of Wi-Fi and LTE-U, they lack the communication channels between them. In dealing with Wi-Fi and LTE-U network coexistence problem, on the one hand, we should take into account the problem of fairness; and on the other hand, since the explosive growth of the number of Wi-Fi users has led to a sharp increase in the number of nodes deployed in different environments, we should pay much attention in the multi-node network to maximize channel occupancy by limiting the LTE-U access opportunity.First, the thesis analyzes the related communication technologies for Wi-Fi and LTE-U systems. We describe principle of the carrier sense and collision avoidance, as well as the key technologies for LTE-U deployment. We also introduce the heterogeneous network interference with Wi-Fi and LTE-U networks related interference coordinating techniques.Then, considering existing link level simulation results for the Wi-Fi and LTE-U heterogeneous network (HetNet), we carry out the system level simulation of the coexistence of Wi-Fi and LTE-U HetNets, and find that the throughput of the Wi-Fi system is decreased dramatically. This is because once the LTE-U access networks coexist, Wi-Fi determines the channel is busy, and will be in a listening state, so the data cannot be transmitted.For the severe unfairness of Wi-Fi and LTE-U HetNets, combining with the heterogeneous network interference coordinating technology, we choose to use a proportional fair allocation solution to the problem of Wi-Fi networks in the long listening state. Next, we find that in the presence of the scene, with the increase of Wi-Fi nodes, the Wi-Fi performance will be greatly reduced.Finally, aiming at the problems of a dynamic threshold mechanism based on CSMA, a multi-node Wi-Fi network solution is proposed which recommends some parameter values relating throughput, bit error rate, exposed and hidden node problems. And the parameter values are used in the Wi-Fi system with the fair coexistence of Wi-Fi and LTE-U, in order to further improve the system performance.