The overall performance of traditional network file system is affected by software overhead when using high-speed storage device. Therefore, a method of constructing a file system using SPDK (Storage Performance Development Kit) was proposed, and a prototype of a network file system RUFS (Remote Userspace File System) was realized on this basis. In this system, the directory tree structure of file system was simulated and the metadata of file system were managed by using key-value storage, and the file contents were stored by using SPDK. Besides, RDMA (Remote Direct Memory Access) technology was used to provide file system service to clients. Compared with NFS+ext4, on 4 KB random access, RUFS had the read and write bandwidth performance increased by 202.2% in read and 738.9% respectively, and had the average read and write latency decreased by 74.4% and 97.2% respectively; on 4 MB sequential access, RUFS had the read and write bandwidth performance increased by 153.1% and 44.0% respectively. RUFS had significant advantages over NFS+ext4 on most metadata operations, especially on the operation of folder creation, RUFS had the bandwidth performance increased by about 5 693.8%. File system service with lower latency and higher bandwidth can be provided by this system via making full use of the performance advantages of the high-speed network and high-speed storage device.

Trajectory privacy protection is critical to the development of Internet of Vehicles (IoV), which makes it important to summarize and analyze existing research methods. Existing IoV trajectory privacy protection methods can be divided into three categories: trajectory obfuscation, pseudonym change and trajectory encryption. Trajectory obfuscation can be achieved based on users' real trajectory or dummy trajectory. Pseudonym change can be achieved based on mix-zone or path confusion. Trajectory encryption can be achieved based on Private Information Retrieval (PIR) protocol or spatial transformation. Firstly, the research background and common attacks were introduced and summarized in this paper. Secondly, existing IoV trajectory privacy protection methods were surveyed from the aspects of methodology, scientific problem and method evolution. The problems need to be further studied also were elaborated. Furthermore, the performances of representative schemes were summarized, such as privacy protection, attack resistance and complexity. Finally, the future research directions of IoV trajectory privacy protection was prospected.

The schemes to solve the high bit error problem in wireless networks were discussed. Aiming to improve the performance of TCP protocal in mobile environments, two typical TCP models of the pure end-to-end approaches, TCPW and TCP-Real,  were researched. The pure end-to-end schemes have the advantage of preserving the end-to-end semantics of TCP protocol. Simulation results with different bit error conditions of these protocols reveal an evident improvement in terms of TCP performance in relative to others, especially when the bit error rate is high.