Time-domain compression of complex-baseband LTE signals for cloud radio access networks
Modern cellular networks such as Long-Term Evolution (LTE) transport complex-baseband samples between remote radio hardware and processing equipment. Common Public Radio Interface (CPRI) links are widely used in practice and enable flexible radio head deployments, distributed antenna systems, and advanced spatial processing such as coordinated multi-point (CoMP) transmission and reception. Current CPRI links already have insufficient capacity to support 20 MHz bandwidth LTE for a basestation with three sectors and four antennas per sector. By supporting eight antennas per sector and up to 5× system bandwidth, LTE-A will require substantial increases in CPRI capacity. In this work, we develop compression methods that exploit the temporal and spectral structure of LTE signals with the goal of achieving high compression with limited impact on end-to-end communication performance. Our contributions include (i) design of a low-complexity compression method for LTE and (ii) validation of this method using an LTE link-level simulation. Our method achieves up to 5× compression for uplink and downlink signals.