The traditional centralized baseband processing architecture is faced with the bottlenecks of high computation complexity and excessive fronthaul communication, especially when the number of antennas at the base station (BS) is large. To cope with these two challenges, the decentralized baseband processing (DPB) architecture has been proposed, where the BS antennas are partitioned into multiple clusters, and each is connected to a local baseband unit (BBU). In this paper, we are interested in the low-complexity distributed channel estimation (CE) method under such DBP architecture, which is rarely studied in the literature. The aim is to devise distributed CE algorithms that can perform as well as the centralized scheme but with a small inter-BBU communication cost. Specifically, based on the low-complexity diagonal minimum mean square error channel estimator, we propose two distributed CE algorithms, namely the aggregate-then-estimate algorithm and the estimate-then-aggregate algorithm. In contrast to the existing distributed CE algorithm which requires iterative information exchanges among the nodes, our algorithms only require one roundtrip communication among BBUs. Extensive experiment results are presented to demonstrate the advantages of the proposed distributed CE algorithms in terms of estimation accuracy, inter-BBU communication cost, and computation complexity.
翻译:传统的中央基带处理结构面临高计算复杂程度和过度前厅通信的瓶颈,特别是在基站天线数量庞大的情况下。为了应对这两个挑战,提议了分散的基带处理结构(DPB),即BS天线被分割成多组,每个天线被连接到一个地方基带单位(BBU)。在本文中,我们感兴趣的是这种DBP结构下低兼容性分布式频道估算法(CE),这种计算法很少在文献中研究。目的是设计分布式CE算法,既可以执行中央计划,也可以执行中央计划,但支付一个小的BBU通信费用。具体地说,根据低兼容性对立式平方差最小平均误差频道估计,我们提出了两种分散式CE算法,即总当值算法和估计式组合算法。与现有分布式的CEE算法相比,我们的算法只需要在BBUs之间进行一次圆形通信,而在CBUs之间进行一次圆式通信的精确性分析,以显示拟议的C-BU计算方法的优势。