CPRI compression transport for LTE and LTE-A signal in C-RAN

C-RAN is the next-generation clean wireless access network architecture, which is based on centralized processing, the Collaborative Radio and Real-time Cloud Infrastructure. In C-RAN architecture, different access technology (eg.GSM / TD-SCDMA / WCDMA / LTE) can be support on the same hardware platform in baseband pool system; C-RAN can be applied to reduce the consumption of operators. LTE (Long Term Evolution) and LTE-A, which are based on OFDM and MIMO technologies, are regarded as the main wireless access technology in the evolution from 3G to 4G. LTE introduces variety of novel technologies to improve the system performance, especially in C-RAN architecture, such as Multi antennas MIMO, Carrier Aggregation, CoMP. However, C -RAN architecture also brings about lager data transmission in the optical fiber. In this paper a low-latency baseband signal compression algorithm used in ALU is introduced to reduce the data rate. Based on the Characteristics of LTE signal data, the algorithm removal redundancies in the spectral domain firstly, and then the block scaling, which is combined with non-linear (nonuniform) quantizer, is designed to minimize quantization error. This algorithm can effectively reduce the amount of data transferred between BBU and RUU in LTE system, to facilitate the deployment of LTE in the CRan architecture. Simulation analysis is given out in the paper; meanwhile TD-LTE system demo verification is also implemented. The results indicate that the scheme introduced can get good performance under a certain compression rate in the real system. Further research is also in progress.