Research On Coexistence Mechanism Of 5G Heterogeneous Networks In Unlicensed Frequency Bands

The rapid development of mobile Internet brings massive mobile data traffic,there are higher demands on mobile operators.In order to satisfy the growing business demands of mobile cellular systems,the 3rd Generation Partnership Project(3GPP)standardization group has proposed Licensed Assisted Access(LAA)technology in the Long Term Evolution(LTE)Release 13.According to the LTE-LAA technology,LTE systems can be implemented from the licensed frequency band to the unlicensed frequency band(such as the 5 GHz frequency band),which effectively alleviates the traffic pressure of the licensed frequency band and meets the user's requirements for QoS.However,it also brings challenges that LAA will affect other wireless access technologies in the 5GHz band largely,such as WiFi.In order to improve the coexistence system capacity under 5G heterogeneous network,reduce the average system delay and ensure the fairness of LAA-WiFi coexistence system,in this paper,we have studied the efficient competition strategies of LAA-WiFi coexistence system as well as dynamic spectrum sharing strategies for co-operators.First of all,an enhanced adaptive energy detection(ED)threshold algorithm based on Jain fairness index is proposed according to the dynamic traffic density,fairness and friendly coexistence.Then,a joint control mechanism for unlicensed spectrum dynamic allocation and power among operators is proposed based on game theory.The main contents and innovations are given as follows.Firstly,an enhanced adaptive energy detection algorithm(eAED)based on Jain fairness index is proposed.The ED value of LAA eNB(evolved Node B)is adjusted adaptively through the change of LAA network density to obtain the higher total capacity of LAA-WiFi coexistence system and lower average system latency.Secondly,the Jain fairness index is introduced to quantify the fairness of LAA-WiFi coexistence system,and the Jain threshold is set to ensure the fairness of coexistence system while controlling the dynamic range of ED value.The simulation results indicate that the coexistence system can be maximized on the premise of ensuring the fairness of LAA and WiFi system according to the eAED algorithm based on Jain fairness index.Thirdly,the mechanism of credit cooperation among operators is established based on repeated game theory.Non-cooperative behaviors are punished based on penalty strategy of P punishment tax.The simulation results indicate that this strategy has realized dynamic allocation of non-authorized spectrum resources among operators,improved spectrum utilization and reduced inter-system interference among operators.Fourthly,the eNB and UE(User Equipment)belonging to a same operator are modeled as Stackelberg game model,which adjusts UE transmission power by setting the price strategy.The simulation results show that this method can reduce system interference,improve energy efficiency,and maximize the revenue of operator and UE.