Spatial Resource Allocation for Spectrum Reuse in Unlicensed LTE Systems
Spatial Resource Allocation for Spectrum Reuse in Unlicensed LTE Systems
复制标题
DOI：
10.1109/glocom.2017.8254944
复制
发表时间：
2017-08
期刊：
影响因子：
--
通讯作者：
Rui Yin;A. Maaref;Geoffrey Y. Li
中科院分区：
文献类型：
--
作者：
Rui Yin;A. Maaref;Geoffrey Y. Li
本文研究了如何在LTE-U系统中重用未授权频谱，同时保证LTE-U和Wi-Fi系统之间的和谐共存。对于基站（SBS）具有多个天线的小小区，一些空间自由度（DoF）用于服务小小区用户（SUE），而其余的空间自由度（DoF）则用于通过应用迫零波束成形来减轻对Wi-Fi用户的干扰（ZFBF）。因此，可以通过仔细分配空间DoF来平衡LTE-U和Wi-Fi吞吐量。由于信道状态信息（CSI）估计和反馈误差的存在，ZFBF不能完全消除干扰。我们首先分析SUE之间的残留干扰，称为RAT内干扰，以及由于不完美CSI而导致的对Wi-Fi用户的干扰，称为ZFBF之后的RAT间干扰。基于分析，我们分别推导出小小区和Wi-Fi系统的吞吐量。因此，提出了空间DoF分配方案以平衡小小区和Wi-Fi系统之间的吞吐量。仿真结果验证了我们的理论分析和所提出的方案。
In this paper, we study how to reuse the unlicensed spectrum in LTE-U systems while guaranteeing harmonious coexistence between the LTE-U and Wi-Fi systems. For a small cell with multiple antennas at the base station (SBS), some spatial degrees of freedom (DoFs) are used to serve small cell users (SUEs) while the rest are employed to mitigate the interference to the Wi-Fi users by applying zero-forcing beamforming (ZFBF). As a result, the LTE-U and Wi-Fi throughput can be balanced by carefully allocating the spatial DoFs. Due to the channel state information (CSI) estimation and feedback errors, ZFBF cannot eliminate the interference completely. We first analyze the residual interference among SUEs, called intra-RAT interference, and the interference to the Wi-Fi users, called inter-RAT interference after ZFBF, due to imperfect CSI. Based on the analysis, we derive the throughputs of the small cell and the Wi-Fi systems, respectively. Accordingly, a spatial DoF allocation scheme is proposed to balance the throughput between the small cell and the Wi-Fi systems. Our theoretical analysis and the proposed scheme are verified by simulation results.