Joint User Association and Fair Scheduling for Dual Connectivity Heterogeneous Networks

Heterogeneous small cell network is one of the most effective solutions to overcome spectrum scarcity for the next generation of mobile networks.Dual connectivity(DC)can improve the throughput for each individual user by allowing concurrent access to two heterogeneous radio networks.In this paper,we propose a joint user association and fair scheduling algorithm(JUAFS)to deal with the resource allocation and load balancing issues for DC heterogeneous small cell networks.Considering different coverage sizes,numbers of users,and quality of experience characteristics of heterogeneous cells,we present a proportional fair scheduling for user association among cells and utilize interference graph to minimize the transmission conflict probability.Simulation results show the performance improvement of the proposed algorithm in spectrum efficiency and fairness comparing to the existing schemes.

HARQ Optimization for PDCP Duplication-Based 5G URLLC Dual Connectivity

Packet duplication(PD)with dual connectivity(DC)was newly introduced in the 5G New Radio(NR)specifications to meet the stringent ultra reliable low latency communication(URLLC)requirements.PD technology uses duplicated packets in the packet data convergence protocol(PDCP)layer that are transmitted via two different access nodes(ANs)to the user equipment(UE)in order to enhance the reliability performance.However,PD can result in unnecessary retransmissions in the lower layers since the hybrid automatic retransmission request(HARQ)operation is unaware of the transmission success achieved through the alternate DC link to the UE.To overcome this issue,in this paper,a novel duplication-aware retransmission optimization(DRO)scheme is proposed to reduce the resource usage induced by unnecessary HARQ retransmissions.The proposed DRO scheme can minimize the average channel use while satisfying the URLLC requirements.The proposed DRO scheme derives the optimal HARQ retransmission attempts for different ANs by solving a nonlinear integer programming(NLIP)problem.The performance of the proposed DRO scheme was evaluated using MATLAB simulation and is compared to the existing 5G HARQ support schemes.The simulations results show that the proposed DRO scheme can provide a 14.71%and 15.11%reduced average channel use gain compared to the selective data duplication upon failure(SDUF)scheme and latency-aware dynamic multi-connectivity algorithm(LADMA)scheme,respectively,which are the existing 5G PD schemes that use HARQ.

Performance Analysis for Mobility Management of Dual Connectivity in HetNet

Dual connectivity(DC)is regarded as a promising technology to increase users’throughput,provide radio link robustness,and improve load-balancing among base stations(BSs).However,since the introduction of DC makes the mobility of network more complex and diversified,especially the mobility management of heterogeneous networks(HetNets)based on DC faces great challenges.Taking event-A3-based measurement report as the trigger condition for handover(HO),this paper compares and evaluates the influences of HO of master nodes(MNs)and secondary nodes(SNs)on link reliability in different bearing modes.Particularly,hybrid automatic repeat request(HARQ),throughput,channel quality indicators(CQIs),and data packets queuing time are taken as link reliability analysis indicators.Besides,we study how DC utilizes the traffic split ratio between MNs and SNs to maximize the superiority of throughput.Simulation results show that DC can effectively reduce the impact of HO on the number of HARQ and increase the throughput of users.When the data traffic is tilted to the secondary nodes,the superiority of throughput is more obvious.

Information Geometry of Positive Definite Matrices

A new Riemannian metric for positive definite matrices is defined and its geometric structures are investigated by means of dual connections introduced to statistical analysis by S. Amari. A few interesting results are obtained and some of those obtained by other authors are extended in our research.