论文标题
当无细胞的大型MIMO符合OTFS调制时：下行链路案例
When Cell-Free Massive MIMO Meets OTFS Modulation: The Downlink Case
论文作者
论文摘要
我们提供了无单元大型MIMO（多输入多输出）系统中正交时间频率空间（OTFS）调制的性能评估。通过利用随时间变化通道的延迟二置（DD）表示的固有稀疏性，我们将嵌入式飞行员辅助通道估计方法应用于后卫间隔减少，并得出从接收到的访问点（APS）中收到上链接飞行员的最小均值误差估计值。每个AP都将共轭光束形成以将数据传输到用户。我们为单个用户下行链路吞吐量得出封闭形式的表达，这是APS，用户和DD通道估计参数的函数。我们将OTF的性能与在高动作条件下（OFDM）的正交频施加多路复用（OFDM）进行了比较。我们的发现表明，与OFDM对应物相比，使用不相关的无细胞大规模MIMO和OTFS调制的MIMO可在95％的每个用户吞吐量中获得高达35％的增益。最后，比相关阴影方案的中位率更明显的是，每个用户吞吐量的增加更为明显。
We provide a performance evaluation of orthogonal time frequency space (OTFS) modulation in cell-free massive MIMO (multiple-input multiple-output) systems. By leveraging the inherent sparsity of the delay-Doppler (DD) representation of time-varying channels, we apply the embedded pilot-aided channel estimation method with reduced guard intervals and derive the minimum mean-square error estimate of the channel gains from received uplink pilots at the access points (APs). Each AP applies conjugate beamforming to transmit data to the users. We derive a closed-form expression for the individual user downlink throughput as a function of the numbers of APs, users and DD channel estimate parameters. We compare the OTFS performance with that of orthogonal frequency division multiplexing (OFDM) at high-mobility conditions. Our findings reveal that with uncorrelated shadowing, cell-free massive MIMO with OTFS modulation achieves up to 35% gain in 95%-likely per-user throughput, compared with the OFDM counterpart. Finally, the increase in the per user throughput is more pronounced at the median rates over the correlated shadowing scenarios.
