Research On Feedback Mechanism In Broadband Mobile Communication System

Mobile communication is the most dynamic and most promising communication method in the field of communication. Its development and popularization changed the society and changed the way of human life. In the traditional macro base station architecture, each base station has its own system, the base station and the supporting equipment are all located in the equipment room. The distributed base station architecture separates the baseband processing part from the radio frequency processing part, and the baseband processing unit (BBU) and RRH point-to-point fiber. Compared with the traditional macro base station architecture, the distributed base station architecture has the advantages of flexible construction mode, small room resource demand, energy saving, etc. C-RAN (Cloud - Radio Access Network) architecture combines centralized processing, cooperative radio and real-time cloud infrastructure, compared to traditional macro base station architecture and distributed base station architecture, C-RAN for mobile operators to bring more low-cost wireless services Access method.C-RAN architecture in cost, capacity and flexibility, etc. show the traditional wireless access network does not have the advantage. However, it also brings some technical challenges, in which the downlink channel state information feedback mechanism is one of the areas that need to be studied.In this paper, a system-level simulation platform is built based on C-RAN architecture. In the simulation platform, a variety of resource management schemes are used in the media control layer by using the channel quality information of the physical layer. The combined transmission scheme and dynamic the performance of the traditional implicit feedback mechanism under the node selection scheme is simulated. The effects of channel measurement and feedback delay on the system performance are simulated respectively from the non-ideal channel estimation and feedback delay.The multi-cell cooperative model of C-RAN architecture is established.With the increase of the number of cooperative cells, the overhead brought by the traditional feedback scheme is doubled. Based on the above, this paper proposes a multi- feedback scheme based on Vector Quantization.This scheme uses the vector quantization technique to compress the feedback of the cell channel information and the inter-cell channel information. The LTE standard codebook is used to construct the quantized codebook space. The simulation results show that the proposed scheme can achieve a good compromise between system performance and overhead.