Communication in optical downlinks of low earth orbit (LEO) satellites requires interleaving to enable reliable data transmission. These interleavers are orders of magnitude larger than conventional interleavers utilized for example in wireless communication. Hence, the capacity of on-chip memories (SRAMs) is insufficient to store all symbols and external memories (DRAMs) must be used. Due to the overall requirement for very high data rates beyond 100 Gbit/s, DRAM bandwidth then quickly becomes a critical bottleneck of the communication system. In this paper, we investigate triangular block interleavers for the aforementioned application and show that the standard mapping of symbols used for SRAMs results in low bandwidth utilization for DRAMs, in some cases below 50 %. As a solution, we present a novel mapping approach that combines different optimizations and achieves over 90 % bandwidth utilization in all tested configurations. Further, the mapping can be applied to any JEDEC-compliant DRAM device.

翻译：低地球轨道(LEO)卫星光学下行链路中的通信需要交织技术以实现可靠数据传输。此类交织器的规模比传统用于无线通信等领域的交织器大数个数量级。因此，片上存储器(SRAM)的容量不足以存储所有符号，必须使用外部存储器(DRAM)。由于系统要求超过100 Gbit/s的超高数据速率，DRAM带宽迅速成为通信系统的关键瓶颈。本文针对上述应用场景研究三角块交织器，发现传统用于SRAM的符号映射方式会导致DRAM带宽利用率低下，在某些情况下甚至低于50%。为此，我们提出一种新型映射方案，该方案融合多种优化策略，在所有测试配置下均可实现超过90%的带宽利用率。此外，该映射方案可适用于任何符合JEDEC标准的DRAM器件。