Channel Estimation Base On Control Domain Data Feedback And Backhaul Data Compression In LTE-A System

Since LTE(Long Term Evolution) technology is widely used and 5G technology is proposed, wireless mobile communication technology has gradually affected people’s daily lives and high-speed data transmission has been widely praised, but wireless transition channel is complex and signal quality is unstable due to the complexion of the environment. Otherwise, C-RAN(C-Radio Access Network) system which is widely utilized in LTE-A(Long Term Evolution Advanced) system adopts the effective deployment of centralized baseband pool and distributed radio frequency transport unit, which decreases the costs of maintenance but adds additional loads. Thus to ensure the accuracy of data transfer in the case of compressed data is a hot issue to discuss. Then how to further improve data transmission efficiency and guarantee the accuracy of data has become a research priority.The thesis studies the classical channel estimation method and analyzes the impact the noise power estimation plays on the channel algorithm. The classical channel estimation is estimated based on pilot channel. Pilot makes the balance between system overhead and estimation accuracy to distribute evenly. Its accuracy depends on the number of pilots and the distance between data signal and pilots. The closed the pilot is to the data signal, the better the effectiveness of estimation is. So how to increase the number of pilots is a direction to improve the channel estimation. Combining the characteristics of the LTE-A downlink physical channel and process to send and receive data, this thesis puts forward a channel estimation scheme based on control domain feedback information as the virtual pilots. Because of the data transmission of LTE-A is determined by the control dominance and the control dominance channel has strict demand of encoding to ensure the accuracy. So the LTE-A control dominance demodulated data is processed and mapped to the resource block to form a virtual pilot which can provide more reference signal for the channel estimation. Through simulation, it shows that the scheme can enhance the number of effective pilots which contributes to the accuracy of channel estimation.Because of Data transmission efficiency not only depends on the channel estimation accuracy, but also is influenced by the Fronthaul systems. After the LTE-A channel estimation gets the accurate channel response value, the compressed data between BBU (Band width Based Unit) and RRU(Radio Remote Unit) can adopt the channel estimation value to transfer. To reduce and control the load of optical, scholars have applied compressed sensing technology in C-RAN Fronthaul system. The method can significantly improve the data compression ratio, but at the receiving end is considered ZF receiver, the accuracy of reconstructed data has decreased. To solve these problems, the reconstructed data is detected and received by the MMSE technique. Finally, the simulation results show the proposed method can improve accuracy of the data transmission.