Research On LTE-U CCA Detection And Related Technology

Duo to the rapid development of mobile streaming media technology and explosive growth of wireless communication equipment in recent years, the spectrum resource of licensed bands is becoming more and more congested. In order to alleviate the conflict between the increasing demand for wireless data and the limited licensed bands resources,LTE system deployed in an unlicensed band is considered to be an effective solution. The unlicensed band has rich spectrum resources, which can alleviate the pressure on authorized-mobile networks to a certain extent, and urge operator and equipment supplier to develop related technologies and equipment actively.Although there are abundant spectrum resources available for development in the unlicensed bands, Wi-Fi is widely deployed as the representative of the communication network in this band. There is no doubt that the introduction of LTE system (LTE-U) would lead to a certain degree of interference to the existing communication network. Therefore,the blank sub-frame (Almost Blank Subframe, ABS), Listen-Before-Talk(LBT) and other solutions are proposed in 3GPP to ensure the spectrum fairness in unlicensed bands between LTE and Wi-Fi.Firstly, the technical characteristics of LTE and Wi-Fi are described in this paper.The channel access mechanism of Wi-Fi system is also analyzed in details. Then, three kinds of coexistence schemes is introduced, which focus on the LBT mechanism and the IEEE 802.11 wireless LAN standard. Finally, a system level simulation platform is built using Matlab in this paper. The effect of different CCA threshold on system performance is analyzed through the simulation under the condition of the coexistence of LTE and Wi-Fi system. Based on this, the enhanced LBT algorithm and the adaptive CCA scheme are studied considering the interference coordination ability of LAA system and the number of Wi-Fi users. That is, the CCA threshold of the target node is adjusted by a certain algorithm to obtain the corresponding system gain. Besides, simulation results show that the proposed scheme can improve the system throughput to some extent in the coexistence environment.