卫星固态存储器数据容错设计与机制

卫星数据传输系统的可靠性面临着空间粒子效应、信道干扰等多重威胁。在介绍数据传输系统关键设备星载大容量固态存储器设计与实现的基础上,从管理信息、数据位流、星地链路、文件传输四个方面构建容错机制,综合应用汉明编译码、RS编译码、低密度奇偶校验码编码等数据检纠错技术,增强存储器管理信息、存储数据、信道传输的容错性能。在实际型号任务固态存储器的基础上,结合CCSDS文件传输协议提出基于自动重传机制的文件可靠传输设计,提高数据传输全流程的容错性能。固态存储器使用多级流水写入、总线并行扩展等技术,吞吐率理论上接近900Mbps,容量达到256Gb。

The Design and Mechanism of the Fault Tolerance mechanism of Solid State Recorder

High-capacity solid state recorder (SSR) has become one standard composition in space borne data handling system. When the spacecraft flies above the domestic ground data receive stations, all the data in SSR would be read out and sent to earth as planed or following the ground orders. The data transmission system is the work platform of the SSR. The work modes and procedures are introduced and they are faced with various threats. The data reliability depends on many segments with different problems. This paper presents the SSR fault tolerance mechanism schedule to cover Single Event Upset (SEU) in semiconductor devices, the Flash retention effect, the transmission noise and so on. The SSR of the satellite is based on NAND Flash medium with a large-scale FPGA and a high-performance Loongson CPU. The SSR uses 4-pipeline writing and bus expansion techniques to achieve the throughput rate of almost 1Gbps theoretically and the capacity of 256Gb. Three EDAC techniques are adopted to protect the data bit streams. The Harmming Code is used to protect management information of SSR, the RS code is used to correct errors in Flash medium brought by the space radiation and interface interrupts, and the Low Density Parity Check Code (LDPC) encoding suggested by CCSDS is used to get a high channel gain between the satellite and the earth. All these techniques are introduced and analyzed. Furthermore, advanced research of one ARQ method based on the SSR platform with CCSDS File Delivery Protocol (CFDP) is also proposed in this paper to improve the reliability in file-level. All the techniques work together to cover the main procedures from different aspects.