论文标题
在多细胞系统中使用线性预编码的高速缓存巨大MIMO
Cache-Aided Massive MIMO with Linear Precoding in Multi-cell Systems
论文作者
论文摘要
在本文中，我们提出了一种新颖的关节缓存和大量的多输入多输出（MIMO）传输方案，称为\ emph {Cache-ateed massive mimo}，用于多核下链接传输到多个启用高速缓存的接收器。通过提出的方案，已将其要求的文件缓存（一部分）的用户被卸载，因此（部分）在下行链路传输过程中（部分）不活动。其他用户可以从启用缓存的卸载中受益，以减轻飞行员污染，或利用缓存但无需的文件以取消上行链路通道估计和下行链路文件接收时取消干扰。此外，通过根据用户的缓存状态和渠道状态信息重新设计传输预编码器，我们获得了大规模MIMO传输的额外自由度。对于给定的缓存状态，我们分析了等效的内容输送率（ECDR），即，通过缓存和大量MIMO传输向请求的用户交付请求的文件的平均速率，用于使用重新设计的最大比率传输（MRT），零型（MRT）（ZF）的（ZF）和正常化的ZERE（ZERE）精确的MIMO，并使用重新设计的最大比率（MRT）和正常化的ZERE（ZERE）。根据派生的结果，研究了（随机）未编码的缓存和编码缓存对重新设计的预编码方案性能的影响。仿真结果验证了我们的推导，并表明缓存对预编码的下行链路传输有益，因为它可以增强发射功率分配，减轻内部和间间内部的干扰，并减少由驾驶员污染引起的损害。与传统的大规模MIMO相比，没有缓存的预编码，即使使用用户数量接近发射天线的数量，也提出的高速缓存大量MIMO方案也达到了ECDR。
In this paper, we propose a novel joint caching and massive multiple-input multiple-output (MIMO) transmission scheme, referred to as \emph{cache-aided massive MIMO}, for multi-cell downlink transmission to multiple cache-enabled receivers. With the proposed scheme, users who have cached (a portion of) the files that they request are offloaded and, hence, (partially) inactive during downlink transmission. The other users either benefit from the cache-enabled offloading for mitigating pilot contamination or exploit the cached but unrequested files to cancel interference during uplink channel estimation and downlink file reception. Moreover, by redesigning the transmit precoders based on the cache status of the users and channel state information, we gain additional degrees of freedom for massive MIMO transmission. For a given cache status, we analyze the equivalent content delivery rates (ECDRs), i.e., the average rates of delivering a requested file via both caching and massive MIMO transmission to the requesting user, for cache-aided massive MIMO employing re-designed maximum ratio transmission (MRT), zero-forcing (ZF) precoding, and regularized zero-forcing (RZF) precoding. Based on the derived results, the impact of (random) uncoded caching and coded caching on the performance of the re-designed precoding schemes is investigated. Simulation results validate our derivations and show that caching is beneficial for precoded downlink transmission as it enhances the transmit power allocation, mitigates intra- and inter-cell interference, and reduces the impairment caused by pilot contamination. Compared with conventional massive MIMO without caching and with cache-oblivious precoding, the proposed cache-aided massive MIMO scheme achieves a significantly higher ECDR even when the number of users approaches the number of transmit antennas.
