Research On Wireless Backhaul Algorithms In Ultra-dense Networks

With the development of mobile wireless communication technology,mobile user devices grow explosively and users' data demand increases rapidly.Low power access points(APs)are densely deployed in the network,which makes it more convenient for users to access to the network.And network capacities in hot spots increase at the same time.Ultra-dense networks can provide extremely high data rates and have the widespread application prospects.Therefore,ultra-dense network has attracted extensive attention of researchers.Ultra-dense network can significantly improve system throughput,but it also brings a series of questions such as strong interference,unbalanced load of APs and limited data rate of wireless backhaul network.There are many APs in ultra-dense network.Considering the infrastructure cost of backhaul links and huge backhaul traffic,how to plan and design wireless backhaul links of each AP to satisfy backhaul data rate requirements of users in ultra-dense network is a key issue.In view of this problem,this paper studies the wireless backhaul algorithms in two typical scenarios of ultra-dense network.In this paper,a distributed wireless backhaul routing algorithm based on throughput maximization is proposed in the user-centric ultra-dense network.Considering numerous and dense APs in the network,we choose to adopt distributed multiple hops approach to plan wireless backhaul links in the network.Every user has a unique access points group(APG).One of the AP in APG is selected as backhaul AP(BAP)and the BAP sends the backhaul request signal.The APs around BAP calculate their own scores,according to the scoring mechanism proposed in this paper,and the score information is a part of backhaul response signal.BAP collects response signals and selects the AP with highest score as its next AP.By this way,the whole wireless backhaul path which meet the demand of backhaul data rate is designed eventually.The scoring mechanism of this paper takes into account channel condition,the loads of APs and signal interference in the network.Meanwhile,the sub-channels occupied by wireless links are selected to meet users' backhaul data rate requirements.Simulation results show the proposed algorithm can balance the loads of APs and maximize the throughput of each link of backhaul path.And the proposed algorithm has a high success rate when planning backhaul path that satisfy backhaul data rate requirements.This paper puts forward a wireless backhaul mode selection algorithm based on energy efficiency maximization in the heterogeneous ultra-dense network.There are some small base stations(SBSs),which are far from macro base station(MBS)or between which and MBS there are some blockings so that these SBSs have poor channels with MBS.For this situation,this paper puts forward indirect backhaul mode where idle SBSs can be a relay for forwarding data to core network.To meet the demand of backhaul data rate well,SBSs can select their backhaul mode in the direct or indirect way to backhaul data traffic.At the same time,in view of serious interference problem,the algorithm also allocates network resources,including the power of BSs and system bandwidth,to enhance energy efficiency of the whole network.At the same time,resource utilization also gets promoted in the network.Compared with the direct backhaul way,the algorithm of selecting backhaul scheme proposed in this paper satisfies data rate demand of backhaul base stations better and maintains a high energy efficiency of the network.