论文标题
FDD巨大的MIMO通道训练最佳速率失真界限和一声方案的效率
FDD Massive MIMO Channel Training Optimal Rate Distortion Bounds and the Efficiency of one-shot Schemes
论文作者
论文摘要
我们研究了在频划分双相（FDD）中运行的多用户大型MIMO系统中提供通道状态信息（CSI）的问题。宽带MIMO通道是一个在时间，空间（天线）和频率（子载体）中相关的矢量值随机过程。基站（BS）会定期广播beta_tr Pilot符号，从其M天线端口到K单人体用户（UES）。相应地，K UES使用上行链路（UL）中的Beta_FB符号发送有关其通道状态的反馈消息。利用远程利率延伸理论的结果，我们表明，随着SNR达到INFTY，最佳反馈策略达到了通道状态估计平均平方误差（MSE），如果beta_tr <r和Theta（snr^（-alpha））在beta_tr> = r> rpha> = rpha = min（beta_fb/is ins ins beta = min/ins ins）时（snr^（ - alpha））的行为（1）（1）。 矩阵。 MSE最佳的率略有策略意味着编码长序列的通道状态，这将产生完全陈旧的CSI，因此多源预言性能差。因此，我们考虑三种实用的单发CSI策略，具有最小的一槽延迟，并分析其大型SNR渠道估计MSE行为。这些是：（1）通过熵编码的标量量化（ECSQ），（2）模拟反馈（AF）和（3）UES和数字反馈的本地频道估计。这些方案在对UE和BS的通道统计知识方面有不同的要求。特别是，后一种策略不需要统计知识，并且受到当前在3GPP标准化中提出的CSI反馈方案的启发。
We study the problem of providing channel state information (CSI) at the transmitter in multi-user massive MIMO systems operating in frequency division duplexing (FDD). The wideband MIMO channel is a vector-valued random process correlated in time, space (antennas), and frequency (subcarriers). The base station (BS) broadcasts periodically beta_tr pilot symbols from its M antenna ports to K single-antenna users (UEs). Correspondingly, the K UEs send feedback messages about their channel state using beta_fb symbols in the uplink (UL). Using results from remote rate-distortion theory, we show that, as snr reaches infty, the optimal feedback strategy achieves a channel state estimation mean squared error (MSE) that behaves as Theta(1) if beta_tr < r and as Theta(snr^(-alpha)) when beta_tr >=r, where alpha = min(beta_fb/r, 1), where r is the rank of the channel covariance matrix. The MSE-optimal rate-distortion strategy implies encoding of long sequences of channel states, which would yield completely stale CSI and therefore poor multiuser precoding performance. Hence, we consider three practical one-shot CSI strategies with minimum one-slot delay and analyze their large-SNR channel estimation MSE behavior. These are: (1) digital feedback via entropy-coded scalar quantization (ECSQ), (2) analog feedback (AF), and (3) local channel estimation at the UEs and digital feedback. These schemes have different requirements in terms of knowledge of the channel statistics at the UE and at the BS. In particular, the latter strategy requires no statistical knowledge and is closely inspired by a CSI feedback scheme currently proposed in 3GPP standardization.
