Resource Management Research In Backhaul Restricted Heterogeneous Networks

With the rapid development of mobile Internet and smart device,the demand for higher data rates presents explosive growth,which w.ill put forward a great challenge to the traditional wireless communication system.Ultra-dense heterogeneous networks,wireless self-backhaul,and NOMA technologies can effectively improve the data-transmission and user access ability of the network.Although the dense deployment of small cell and NOMA will improve the capacity of the system,they also bring more interference to the network and put higher requirement to the backhaul.Wireless self-backhaul is a good choice as it is both faster and more cost-effective,but it will make the resource allocation more complex.So these technologies will put forward higher requirements for resource management in wireless self-backhaul.Therefore,two resource allocation schemes were proposed respectively for the OMA self-backhaul heterogeneous network scenario and the NOMA self-backhaul heterogeneous network scenario.The main innovation of this thesis are as follows:A joint slot and sub-channel scheduling algorithm in OMA self-backhaul heterogeneous networks is proposed.We formulate a slot and sub-channel allocation optimization problem to maximize the downlink throughput of the system subject to user data rate requirements and access-backhaul link matching constraints.Since the formulated problem is Integer Non Linear Program whose solution is intractable,the following schemes are proposed to solve it.Firstly,a transmission state division algorithm is proposed to control the cross-layer and cross-link interference.In order to further eliminate the inter-cell interference,a graph based small cell clustering algorithm is proposed.Secondly,a Linear Problem is formulated for solving the slot allocation problem.Thirdly,several low-complexity algorithms for sub-channel allocation are proposed.Each base station can use corresponding sub-channel allocation algorithm in a distributed manner.The simulation results show the proposed scheme can effectively meet the basic data rate demand of users and achieve significant gains in system downlink throughput as compared to comparison schemes.A joint user pairing and power allocation algorithm in NOMA wireless self-backhaul heterogeneous networks is proposed.We formulate a resource allocation optimization problem to determine the user pairing and transmission power allocation.Because the formulated problem is a Mixed Integer Non-linear programming,we transfer the original problem into three sub-problem.Firstly,the multiplexing relationship between the small base station and the macro base station is obtained based on the interference information,and we can estimate the downlink transmission capability of all the base stations and the time slot ratio of each working states.Then,the user pairing can be done based on the channel state and the data rate requirement satisfaction.Finally,the power allocation optimization problem is constructed subject to user rate requirement constraint,access backhaul matching constraint and transmission power constraint.Since the problem is non-convex,an iteration algorithm is used.The simulation results illustrate that the proposed scheme can obtain significant gains in system downlink throughput as compared to OMA scheme,and the throughput will increase with the increase of the number of small base stations.