Research On Energy Efficiency Optimization Of Distributed Multi-antenna System

Considering the explosive growth of mobile terminals,the future wireless communication network has a higher demand for network energy efficiency(EE).Ultra dense network(UDN)consisting of numerous densely deployed small cells has great potential to improve network EE.At the same time,distributed multi-antenna system(DAS)can also improve the network EE by deploying the antennas in multiple distributed antenna units(DAUs).Therefore,we prefer to introduce DAS into UDN to further improve the network EE.However,with the increase of small cells and antennas,the network power consumption will greatly increase and affect the system EE.Furthermore,the intra-cell interference and inter-cell interference can complicate the EE optimization.Fortunately,it has been proved that effective resource allocation scheme can reduce power consumption and increase the network EE.Moreover,a low-complexity distributed method,game theory,has been widely used for resource allocation.Therefore,the paper aims to develop a more efficient EE optimization scheme based on game theory.Specifically,the main contributions of the paper are as follows.1)In order to improve the system EE of UDN with DAS,a novel distributed non-cooperative power allocation game with leakage interference-to-signal ratio constraints has been proposed.Specifically,in each cell,based on the fog radio access network architecture,multiple DAUs are connected to a mobile edge computing server to provide collaborative service to the users.Taken the backhaul power consumption into consideration,each cell individually optimizes its own EE while restricting the leakage interference to other cells through the constraint.It has been proved that the scheme has a unique Nash equilibrium(NE).Finally,simulation results show that the proposed scheme effectively improves the system EE.2)In order to further improve the system EE,the paper proposes an EE optimization scheme based on a two-level game to jointly optimize power allocation and antenna selection.Specifically,the above non-cooperative power allocation game scheme and the following discrete non-cooperative DAU selection game scheme operate alternately,each using the results obtained by the other game as inputs.When two games reach the NE at the same time,the joint optimization algorithm converges to the optimal EE.Simulation results show that the proposed joint optimization scheme can significantly improve the network EE.3)Considering that the number of DAU is discrete,the paper proposes a discrete non-cooperative DAU selection game based on the discrete game.Specifically,each cell acts as a game player and sorts the DAUs in ascending order according to the distance from the users.Then turn on the DAU one by one until the optimal cell EE is obtained.After multiple rounds of games,when all players cannot improve EE by changing its own strategy,the game converges to the optimal solution.Finally,simulation results show that the proposed scheme can obtain similar system performance to the exhaustive search algorithm with low complexity.