Cell Outage Compensation For 5G Heterogeneous Cloud Radio Access Network

With the rapid development of mobile communication services,people have higher demand for high speed and stability of mobile network.5G H-CRAN,a heterogeneous cloud radio access network,has the characteristics of centralized resource processing and intensive deployment in hotspots.It can significantly improve network service quality and provide better business experience.Network outage compensation can quickly perform network repairs when network failures.It improves user experience in time,and meet the needs of high-speed and reliable communication services.The research of outage compensation in 5G H-CRAN is of great significance.5G H-CRAN is mainly composed of three parts.High Power Node(HPN)is compatible with 4G equipment to achieve seamless coverage.Low Power Node(LPN)is densely deployed to achieve local capacity improvement.Base Band Unit(BBU)is centrally placed in the BBU pool to realize flexible scheduling.Since different outage scenarios will have different severity of impacts on the network,the goals of network repair and the technologies used will also change accordingly.This paper focuses on multiple outage scenarios of 5G H-CRAN:LPN outage,HPN outage,multi-HPN outage,regional outage of HPNs and LPNs.The current research of 5G H-CRAN has the following problems:1)For LPN outage,due to the dense deployment of LPN,the power adjustment of adjacent LPNs will cause serious interference.And it cannot solve the problem of resource shortage.Existing research fails to comprehensively consider maximizing the number of user connections and optimizing power loss.2)For HPN outage,only relying on the adjustment of the adjacent HPN inclination for compensation will cause interference enhancement.Existing studies have failed to consider the two issues of reducing coverage hole rate and reducing coverage overlap rate at the same time.3)For multiHPN outage,the adjustment of neighboring HPN alone cannot meet the compensation demand.Device-to-Device Communication(D2D)is applied to the outage compensation mechanism.The existing research on interrupt compensation through D2D technology does not consider the sustainability of the network and the power consumption of the terminal,and does not consider the overall network capacity.4)For regional outage of HPNs and LPNs,the compensation demand cannot be met by relying on existing equipment alone.In the existing research on compensation for interruption through air base stations,there is a lack of joint heterogeneous deployment of air base stations of different types and different frequency bands,and the problem of capacity improvement in local hot spots has not been solved.In view of the above problems,this paper studies the H-CRAN outage compensation mechanism for different scenarios of 5G H-CRAN.The main innovative research contents are as follows:(1)For the problem of serious interference of LPN intensive deployment and and esource shortage in LPN outage,an emergency communications strategy based on coordinated multiple points is proposed.The scheme based on cooperative transmission comprehensively considers factors such astransmit power,resource limitation and user transmit rate.It takes advantage of the characteristics of intendive LPN deployment and flexible resource allocation.The compensation model with the aim to maximize the number of connected UEs and optimize power regulation is solved by Benders’ decomposition algorithm.The simulation results show that this mechanism can quickly and stably restore network coverage.While improving the probability of system outage restoration,it can effectively reduce interference and power consumption,and reduce resources occupied.(2)For the the problem of interference enhancement and resource shortage by adjacent HPN parameter adjustment in HPN outage,an emergency communications strategy based on antenna tilt adjustment is proposed.The scheme comprehensively considers factors such as centralized resource scheduling and adjustable tilt.The tilt adjustment and cooperation technology are used.And it considers the characteristics of SINR,received power and throughput.The problem model is set up with the goal of reducing coverage gap and coverage overlap.An enhanced immune-genetic algorithm is proposed innovatively to solve this problem.The simulation results demonstrate that it can reduce network coverage gap and network coverage overlap,effectively reduce interference and improve user receiving power and network throughput while quickly restoring network coverage.(3)For the problem of insufficient coverage of adjacent HPNs in multi-HPN outage,an emergency communications strategy based on Device-to-Device multicast is proposed.D2D technology is used in this mechanism.The sustainability of communication is an important index to sets up the problem model with the goal of improved network capacity.The Hungarian Algorithm based on throughput-aware is used to channel multiplexing.Simulation results show that the mechanism can improve compensation coverage and restore the outage users link state,and greatly prolong the user’s sustainable communication time on the premise of limited resources.(4)For the problem of existing hardware devices is unable to service in regional outage of HPNs and LPNs in emergency scenario,a network compensation mechanism with multi-state aerial base stations deployment,which is based on energy efficient resource optimization is proposed.The scheme comprehensively considers factors such as the flexibility of AeBSs,the scalability of mmW UAV.Then a problem model with the goal of high energy efficiency is built.And it is decomposed into three sub-problems to be solved separately.The coverage problem of AeBS and AeRRH is solved through the equal circle filling algorithm and fixed coverage greedy deployment algorithm.The gradient enhanced greedy expectation maximization is used to implement the mmW-UAV to enhance local capacity.The deep reinforcement learning algorithm is used to allocate resources to optimize energy efficiency.Simulation results show this mechanism can quickly build an emergency network through the air base station when the existing hardware equipment can not continue to be used.And it realizes the coverage recovery of the communication network and the capacity enhancement of local hot spots.