Study On The Coexistence Strategy Of LTE And WiFi On Unlicensed Bands

With the explosive growth of various mobile intelligent devices, the system capacity of wireless communication needs to be improved, but the licensed bands resource is always the bottleneck of the system capacity. LAA(License Assisted Access) technology enables LTE to operate on unlicensed bands, which is promising to enhance LTE system capacity efficiently.However, coexistence between LTE and other wireless communication systems on unlicensed bands has become a key problem to be solved.This paper analyzed coexistence methods and key technologies between LTE and Wi-Fi. The existing coexistence technology is mostly realized by the single dimension of resource allocation in time domain or frequency domain,while the resource allocation mode of the combination of time domain and frequency domain is less studied. This paper focused on the issue of carrier switching in the case of multi-carrier, and proposed a dynamic channel switching algorithm based on proportional fairness. In order to adapt to the carrier switching scene, this paper presented an enhanced LBT (Enhanced Listen Before Talk) mechanism, introducing the concept of freezing period where LAA can perform appropriate switch and release decision of channels for other communication system to use. Taking into account the carrier selection problem, this paper proposed a selection strategy based on proportional fair. Through this strategy, LAA can dynamically switch channel according to the selection probability and effectively use the unlicensed bands.In order to further improve the system performance, the Q-learning based multi-carrier data transmission algorithm is proposed in this paper,aiming at solving the problem of radio frequency leakage in multi-carrier data transmission. In the synchronous channel selection, considering the two factors of the performance gain of system and the adjacent channel radio frequency leakage, the collection of the proper synchronous carriers was chosen based on Q-learming. Based on the synchronous carriers, LAA select the transmission channel by multi-carrier LBT to conduct carrier aggregation and data transmission. The proposed algorithm can effectively reduce the adverse effects of adjacent channel radio frequency leakage problems on the system performance.Finally, based on the system level simulation platform, the two algorithms are simulated and the performance of the algorithms is evaluated and analyzed.