Research On Green Communication Technologies For 5G Mobile Networks

The rapid adoption of 5G mobile technology leads to explosive growth in mobile data service,which increases the energy consumption of mobile network.Due to the fact that most of the energy consumption in 5G mobile networks comes from the energy consumed at base stations,in order to improve the energy efficiency of the communicaiton system,we should aim at easing the energy supply burden for base stations.Therefore,with the aim of achieving green communcation for 5G networks,in this thesis,we leverage the ultra-dense networking technology and energy harvesting assisted D2D communication technology to improve the spectrum efficiency and energy efficiency of existing mobile networks while ensuring the quality of service.First,ultra-dense networking improves the spectrum efficiency and energy efficiency of mobile network systems by densely deploying low-power and low-cost small cells base stations.However,the densly deployed base stations complicates the management of wireless resources due to the severe interference introduced by crowded data transmissions.Therefore,with multiple avaiable base stations,the user access strategy should be carefully designed to fully reap the benefit of small cells.Moreover,D2D communicaiton technology can realize direct data transmission between two end users without the help of base station,which offloads a large amount of data traffic at base station and therefore decrease the energy consumption at base station.Due to the limited battery capacity at end devices,it would be more efficient if the energy harvesting technology could be applied to support the tranmission energy requirement.Note that since the energy arrival probability replies on the surrounding envrionment,the amount of available energy at transmistter device is usually stochastic.Therefore,it is of great imporatnat that the channel statistics of available spectrum and stochastic characteristics of energy arrival are taken into consieration to design the spectrum access and power allocation strategy.The main contraibution of this paper is listed as follows.First,as for the user association problem in ultra dense networks,we propose a distributed small cell selection algorithm based on the first-level price sealed auction game.We construct the utility functions of both the users and the small cell base stations,and then derived the bidding price of the small cell base stations and the selection of the users based on the utility functions.Moreover,we develop the strategy of a multi-round auction game based on the network status.Simulation results show that the performance of proposed algorithm is competitvie in terms of the user acceptance rate and the average data rate.Moreover,we combine the energy harvesting technology with the D2D communication technology to offload data traffic from base station to the edge of network so that the energy consumption at base station could be reduced.Under the constraint of ensuring the quality of service at each D2D communication pair,we propose an energy efficient joint channel allocation and power allcation strategy.By jointly considering the intereference among D2D pairs and the stochastic process of energy arrival,we formulate an long-term energy consumption minimization problem,which falls in the category of integer optimization problem.To efficiently solve the problem,we design a channel allocation strategy based on the distance among D2D pairs,as well as a power allocation strategy based on genetic algorithms.Through simulation restuls,we show that the performance of our proposed strategy is competitive under different network settings.