Downlink Resource Allocation Scheme For Indoor VLC-WiFi Heterogeneous Networks

Indoor VLC-WiFi heterogeneous networks has become an networking scheme with great development prospects for short distance wireless communication,because it not only has the advantage of high-speed owing to visible light communication(VLC)technology,but also has the advantages of reliability and broadness owing to wireless fidelity(WiFi)technology.However,the inter-cell interference caused by the dense deployment of multiple access points(APs)is an important factor restricting the performance of indoor VLC-WiFi heterogeneous networks.Researching the downlink resource allocation method based on interference suppression has become the key in improving the performance of heterogeneous networks.In addition,in view of the differentiation of user requirements for quality of services(QoS)and the problem of scarce communication resources making it difficult to increase network capacity,researchers urgently need to consider cross-layer resource allocation method based on QoS awareness to improve resource utilization.Based on the above problems,this thesis conducts an in-depth study on the downlink resource allocation scheme for indoor VLC-WiFi heterogeneous networks.Aiming at the inter-cell interference problem of indoor VLC-WiFi heterogeneous networks,a user-centric access method based on static spectrum allocation is proposed in the third chapter.The VLC spectrum is divided into multiple frequency bands,which are allocated to adjacent VLC APs regularly to suppresses inter-cell interference,and then non-interference APs is associated with the user to increase their data rate.Due to the lack of flexibility in static spectrum allocation,a dynamic carrier allocation method based on user-centric access is also proposed.The number of VLC APs associated with the user is determined based on the user request rate,and then the deference value between the user request rate and network service rate is calculated.The user’s associated VLC APs are arranged in descending order of the difference value,and the interference free sub-carriers meeting the load requirement of VLC AP are allocated to each of them in turn.Aiming at the residual interference caused by sub-carrier multiplexing,a transmit power control method based on residual interference suppression is designed,which controls the transmit power of VLC AP that will improve the system overall performance.Simulation results show that the proposed method obtain the higher system throughput,serves fairness,and user satisfaction.Aiming at the problem of insufficient network capacity caused by the growth of user QoS requirement,firstly,a cross-layer dynamic resource allocation mechanism for downlink transmission link QoS awareness is designed in the forth chapter.Secondly,a downlink transmission link QoS awareness level evaluation formula and user data packet QoS requirement level division rules are designed.Thirdly,a QoS-aware cross-layer dynamic resource allocation method is proposed for selecting an appropriate packets transmission link and bandwidth.Finally,a NOMA user matching and power allocation strategy is proposed to further expand the network capacity.Simulation results show that the proposed method obtain the higher system throughput and lower buffer queue length.