A compression scheme for LTE baseband signal in C-RAN

In C-RAN, the baseband units (BBU) and the remote radio heads (RRH) are separated, using the Common Public Radio Interface (CPRI) to transport data to each other. It is based on centralized processing and Real-time Cloud Infrastructure, which requires significant transport network resources. A low latency compression scheme of LTE downlink baseband signal based on clustering algorithm is presented in this paper to reduce the CPRI transmission bandwidth in C-RAN. The main procedure of algorithm is removing redundant bandwidth VQ data in frequency domain, clustering and quantifying the points on the constellation, and finally selecting an appropriate coding scheme adaptively. The Matlab simulation and FPGA-based performance analysis are presented in this paper to verify the compression algorithm. Under the premise of that EVM is less than 0.025%, especially in low throughput scenarios, the data compression ratio can reach about 4%. Moreover, the compression scheme has a strong independence and versatility, and can be used as a standalone module directly added to the current LTE system.