Processor based 20Mhz 4×4 Cat-5 LTE MIMO receiver with advanced detectors

The Category-5 (Cat-5) UE defined by LTE, as the most demanding category, requires processing 20Mhz bandwidth and 4×4 MIMO transmissions. Very little progress has been reported for its feasibility on programmable processors. In fact, most related work focus on lower categories with much less throughput. Since MIMO signal processing complexity increases non-linearly even with the simplest linear MIMO detectors, 4×4 MIMO transmissions combined with 20Mhz bandwidth is much more challenging when compared to lower UE categories. Our work explores the feasibility of software defined baseband for the most demanding UE category. On a customized SDR baseband processor, we have recently accomplished a software defined downlink inner receiver for Cat-5 LTE UE. The implemented inner receiver includes fully fledged synchronization and data detection functionalities, including coarse CFO estimation/compensation, I/Q imbalance estimation/compensation, OFDMA demodulation, channel estimation, fine SCO/CFO estimation/compensation, MIMO channel processing, MIMO data detection and LLR generation. Both linear MIMO detectors and more advanced MIMO detectors have been studied. To the best of our knowledge, this is the first work experimenting practical Cat-5 LTE receivers on baseband processors.