Architecture Design And Application Research For Convergence Of LTE And WiFi In Unlicensed Spectrum

With explosive growth of smart devices and continuous emergence of mobile multimedia services,cellular systems are facing the challenge of blowout-type data traffic demand.In this context,wireless operators considered introducing LTE(Long Term Evolution)in unlicensed frequency bands to boost cellular system capacity.Current researches mainly focus on the coexistence of LTE and WiFi(Wireless Fidelity)within unlicensed bands.However,the successful realization of harmonious unlicensed spectrum sharing requires more than mere consideration of coexistence.Five aspects need to be considered: 1)the lack of advanced level of mutual cooperation leads to inefficient unlicensed spectrum sharing;2)the lack of comprehensive platform with resource management results in degradation of resource utilization;3)access infrastructures from different owners are deployed redundantly results in excessive capital and maintenance costs;4)delay-sensitive services put forward higher requirements on computing and storage capabilities of network edges;5)with the densely deployed access systems,user equipments need to frequently switch channels,which incurs significant signaling overhead and high energy consumption.To tackle above challenges,the key solution relies on the mutual cooperation and consolidated management among different access technologies.Motivated by this,this research designs and implements a converged architecture for the unlicensed spectrum sharing of LTE and WiFi.The main research content and contributions are listed as follows:(1)This research proposes a new converged architecture to enable the harmonious unlicensed spectrum sharing between LTE and WiFi.In the architecture,the base station functionalities of different access systems are abstracted from the underlying physical infrastructures,which benefits the seamless cooperation and flexible resource allocation.Hierarchical computing framework places a massive number of computing and storage resources at the network edge and scattered across various locations,which enables the network edge intelligence.The control-data coverage decoupling boosts the network energy efficiency。(2)To explore the feasibility of the proposed architecture,this research takes the convergence of LTE-U(LTE-Unlicensed),the candidate technology of LTE in unlicensed bands,and WiFi as the case study.The duty-cycled convergence strategy is proposed.The strategy makes full use of the convergence feature of the proposed architecture,and it can adaptively defer the start time of LTE-U ON duration according to the Wi-Fi transmission status.(3)To demonstrate the efficiency of the proposed strategy,this research implements the converged LTE-U and WiFi on a general purpose processor-based software defined radio hardware test-bed.WiFi system is realized based on open-source project,while LTE-U system is self-developed.Novel LTE-U synchronization algorithm is designed to reduce the time complexity.Real-world indoor experiment is conducted to provide a systematic evaluation of the architecture.The experimental results show that the proposed strategy can achieve a better performance than the existing coexistence mechanism.