Research On Resource Management Key Technologies In Ultra-dense Network

Ultra-dense network is a new network structure for the 5^th Generation which can make users closer to low power base stations and improve the spectral efficiency.Due to the dense distribution of users and low power base stations in ultra-dense network,resource management is an important factor to ensure its system performance.Firstly,the users in ultra-dense network are likely to concentrate in certain areas.So it will cause the unbalanced load among cells,and the limited wireless resources cannot be fully used.Secondly,due to dense deployment of low power base stations,the interference environment becomes more complex than traditional cellular network.The user scheduling schemes based on user-centric virtual cells are widely applied to handle interference well.So mobility load balancing,interference management and virtual cell are three key technologies of resource management in ultra-dense network.This thesis begins with the above three key technologies,and studies the inter-cell handover process based on mobility load balancing,the interference management based on dynamic clustering and the user scheduling schemes based on user-centric virtual cell.The main innovations of this thesis are listed as follows:?1?This thesis proposes a mobility load balancing algorithm in ultra-dense network.The algorithm classifies cells according to the load of each cell,and adjusts cell individual offset based on the load of cells,thus adjusting the condition of handover.In the premise of the conditions to meet the handover,one over-loaded cell can unload users on some light-loaded cells which are adjacent.And more than one mobility load balancing processes can work at the same time.This scheme can not only balance the load among cells and make full use of the wireless resources,but also reduce the interference in over-loaded cells and avoid the ping-pong effect.?2?This thesis considers the uplink transmission of ultra-dense network,and proposes a dynamic clustering algorithm.The algorithm sets a signal-interference matrix and adjusts the cluster parameter to make a better tradeoff between the system performance and complexity.The algorithm clusters low power base stations flexibly,reduces interference and leads to significant system capacity gains.?3?This thesis considers the downlink transmission of ultra-dense network,and derives an ergodic sum rate expression from the probability density function of users'signal to interference plus noise power ratio.The simulation result demonstrates the correctness of the ergodic sum rate expression.This thesis proposes two user scheduling algorithms based on virtual cell in ultra-dense network:one based on minimum distance and another based on pattern search.This thesis calculates users'ergodic sum rate and computation complexity of the two algorithms,respectively.The system performance and computation complexity of these two algorithms have their own merits.Compared with traditional user scheduling algorithm,the algorithms proposed in this thesis can reduce interference and improve users'ergodic sum rate.