The Implementation Of Multi-user LTE Air Interface Based On Transparent Transmission

LTE (Long Term Evolution) technology is a new generation of wireless communication technology, which is a better way to transport video in the mobile wireless environment. Based on the actual needs of the project, with the help of LTE technology an air interface protocol stack which is transparent to the bottom protocol and supports multiple users in two-way communication is designed and implemented.The system on which the protocol stack is running involves two protocol network. In specifications, the cable end of the system involves the Ethernet protocol, and the wireless end bases on the LTE air interface protocol. The transport layer software based on the Ethernet protocol has a plurality of transmission modes, which increases the difficulty and complexity when accessing devices designed by different manufacturers. In view of that, this paper presents a transparent way for unifying treatment on the Ethernet device, which can be compatible with various types of different manufacturers’ devices. Meanwhile, the method not only simplifies the processing, improves the performance, but also saves resources. 3GPP (The3rd Generation) LTE air interface protocol provides a series of rules and constraints, but does not provide any practical implementation algorithm. According to the currently published literatures, the research on LTE protocol focuses on the physical link, while the upper layer protocol stack is rarely involved. In order to meet the requirements of high efficiency and reliability of multiuser video transmission system, based on LTE protocol three kinds of data transmission mode (transparent mode, non-acknowledged mode, acknowledged mode) are realized to complete the data transmission. Sliding windows both in the sending end and receiving end are realized by lock-free buffers based on the Microblaze instructions. At the same time, in order to prevent performance from decreasing this paper adopts the Copy-on-Transmission mechanism, which could delay data copying until the real delivery, to reduce data memory copying between the cable end and the wireless end. Finally, a number of tests are conducted to verify the correctness and availability of the protocol stack.