To solve the problem of low consensus efficiency of Blockchain version of DLS （BDLS） consensus algorithm in a system with a large number of nodes and hierarchy， an blockchain consensus improvement algorithm HBDLS （Hierarchical Blockchain version of DLS） based on BDLS was proposed. Firstly， nodes were divided into two levels according to the attributes of nodes in practical applications. Each high-level node managed a low-level node cluster respectively. Then， cluster consensus was carried out on all lower-level nodes， and the consensus results were reported to the corresponding higher-level nodes. Finally， the consensus results of all the high-level nodes to the lower level nodes were agreed again， and the data passed the high-level consensus was written into the blockchain. Theoretical analysis and simulation experimental results show that in the case of 36 nodes and a single block containing 4 500 transactions， the throughput of HBDLS is about 21% higher than that of BDLS algorithm； in the case of 44 nodes and a single block containing 3 000 transactions， the throughput of HBDLS is about 52% higher than that of BDLS algorithm； in the case of 44 nodes and a single block containing 1 transaction， the consensus latency of HBDLS is about 26% lower than that of BDLS algorithm. Experimental results show that HBDLS can significantly improve the consensus efficiency for the system with a large number of nodes and a large transaction volume.

Focused on the problem of low storage density in embedded systems, in this paper, a new NAND device management solution with high storage density was proposed. In the proposed solution, a generalized mode of information structure in NAND page was designed by researching a great number of NAND storage structures and BCH(Bose-Chaudhuri-Hocquenghem) parity coding programs. In the mode, data layout in Out of Band (OOB) could achieve Error Correcting Code (ECC) capability while accommodating device management information of partition, thus the main page could be completely used for data storage, which can be treated as a basis for development of device read-write solution and Wear Leveling mechanism. The experimental results show that the proposed solution improves storage density up to 98%, and it is superior to most current common file systems. Having an excellent data storage density, as well as relatively stable device read-write efficiency and Program/Erase (P/E) endurance, the solution has good application advantages in embedded systems.

In this paper, an novel virtual EEPROM based on flash device was designed, which focused on the current urgent need for low-cost in embedded systems especially, The virtual EEPROM was used as NAND device part in embedded Operating System (OS), which used data backup mechanism to ensure data security. Considering that NAND only supports page programming, a method of log update based on memory buffer was employed to realize byte programming in Virtual EEPROM. Finally, to achieve unified management of NAND block, a wear leveling was designed, meanwhile, issues of bad block and Program/Erase cycle were greatly optimized. The result shows that the Virtual EEPROM has fast programming characteristics of NAND, as well as a great advantage of endurance over the EEPROM. The design has good compatibility and can be widely transplanted in various embedded platforms.