Research On Key Techniques Of Interference Suppression Based On Network Assisted In LTE-A System

To achieve faster data transfer rate and higher spectrum efficiency, the same frequency networking mode has been made extensive use of in the mobile communication systems in recent years. Generally, this mode, by which the adjacent cells share the same frequency, will inevitably lead to serious co-channel interference among the cell edge users and decrease the system performances including the throughput and the transmission efficiency eventually. Therefore, research on suppressing the co-channel interference between cells is of great importance.So far, mainstream interference suppression technologies such as interference coordination technology, interference randomization technology and CoMP technology are basically realized in base station, in CoMP system, for example, the end users feed back channel information to the base station real-timely and the base station proceeds the corresponding joint processing or coordinated beamforming. However, with the constant improvement of the processing speed and processing capacity and the continuous reduction of the power consumption, terminal baseband digital signal processing ability is capable of real-time interference suppression, moreover, reducing the burden of the feedback link and the system time-delay.Aiming at how to solve interference among the cell edge users, the present paper studies the receiver interference suppression technology and power allocation technology which can improve the system throughput, its main content is:Firstly, this paper introduces the history of LTE technology, analyzes the current interference problems of the communication system and briefly describes the development status of interference suppression technologies.Secondly, this paper introduces several kinds of network assisted enhanced interference suppression receiver technologies, analyzes their algorithm principle and application scenarios, compares their performances and constructs the interference channel simulation model. Then respectively verifies the NAICS algorithm has good ability of interference suppression and can effectively improve the system throughput and transmission efficiency under different environment of the interference level.Thirdly, this thesis uses the multi-streaming multi-user interference model to combine NAICS algorithm and power allocation strategy, further improve the system throughput. After that, two power allocation algorithms are presented respectively, one is traversal algorithm and the other is low-complexity power allocation algorithm, the former has optimal performance but higher complexity, the latter compromises the performance and complexity.In the forth part, based on FPGA hardware platform, we implement the symbol-level interference elimination algorithm with RTL code; analyze and design the hardware temporal logic of the key modules in detail, which including the frequency offset compensation, channel estimation and noise reduction module, etc; and complete the system board-level verification finally. The test results show that the interference elimination NAICS algorithm has a good effect.In the final installment of this paper, the main work of this thesis is summarized and further research and improvement work that need to be done are also brought forward.