Research On Coordinated Multi-Point Technology Based On Compressed Sensing

Coordinated Multi-Ponit (CoMP) is the core technology of Long Term Evolution Advanced (LTE-A), which aim to improve edge user throughout as well as the overall data transfer rate of the network. Precoding technology is a major technology of CoMP joint transmission, the decoding process requires cooperative base station signals simultaneously arrive at the user terminal. In pratice network, due to the randomness and mobility of mobile location, CoMP is difficult to ensure that the signal can be simultaneously or in less time delay difference reaches the user terminal, according to limited feedback of user. It raises the problem of asynchronous interference between multi-user. Currently, researchers mainly to eliminate asynchronous interference by design new precoding method with limited feedback, but these preoding schemes generally have high complexity. This paper with the basics of advanced compressive sensing technology, througt design of low sampling rate compression scheme to extrace signal of interest, which can effective eliminate the asynchronous interference.This paper firstly describes CoMP joint transmission technology and build heterogeneous communication network mode] which combines relay and CoMP technology, then analysises the problem of asynchronous interference in heterogeneous network. Asynchronous interference is caused by different propagation times between the cooperative base station and mobile stations between multiple users, which lead to inter-carrier interference after the Fourier transform demodulation. Literatures have demonstrated that with the use of partial Fourier transform can effectively reduce the impact of inter-carrier interference on the system performance. The paper bases on the existing literature’s ideas, extending the discrete time domin fast Fourier sampling to the continuous time domain, and proposing compressed sensing interference cancellation method with the basics of random partial Fourier transform. Firstly, let the received signal pass the multi-channel analog-information converter, which lead to the random frequency shift of spectrum. Secondly, extracts the signal of interest through the filter group, and then sample information with sub-Nquist rate as well as partial Fourier transform. Thirthly, estimates the frequency location and corresponding coefficients which contain important informations.The compressive sensing algorithm proposed in this paper is based on Partial Fourier transform. It only extracts the main frequency information of sub-carriers and it can effectively reduce the impact of asynchronous interference on the system performance. Simulation results show that continuous time-domain fast Fourier sampling system can receive LTE-A signals with sub-Nyquist rate, while effectively eliminating asynchronous interference. If the signal is band limited to 10MHz, and the carrier frequency is 2GHz, then the Nyquist rate of this signal is 4.01 GHz according to Shannon Theorem. When the received signals are not affected by asynchronous interference, the continuous time-domain fast Fourier sampling system proposed in this paper can sample the signal with 1.296GHz, it has proved that the performance is similar to the traditional system which fistly sample the signal with 4.01 GHz and then through FFT demodulation. When the received signals are affected by asynchronous interference, a sharp drop occurred in signal reception performance using traditional method. However the method proposed in this paper can reduce the bit error rate to less than 10-4 when the sampling rate is 1,296GHz and the SNR is 30dB.