Overview of a Software Defined Downlink Inner Receiver for Category-E LTE-Advanced UE

With the soaring development cost of deep sub-micron silicon and the fast-growing diversity in wireless communications, software defined baseband becomes more and more important for handheld devices. However, most software defined receivers reported in previous literatures are still far away from fulfilling the requirement of emerging wireless standards such as the LTE-Advanced. The category-E User Equipment (UE) defined in LTE-Advanced, as the most demanding category for handheld devices, requires processing 2 concurrent data streams at around 300 Mbps aggregated throughput. It is not clear whether SDR baseband processors can tackle this challenge. In our work, we explore the feasibility for software defined baseband for LTE-Advanced. With a highly customized SDR baseband processor, we have recently accomplished a software defined downlink inner receiver for Category-E LTE-Advanced 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. This paper is intended to bring an overview for the work and emphasizes key aspects that enable the feasibility of the work. In this paper, we will introduce the algorithm and processor architecture co-design flow, overall receiver functionalities, important optimizations and implementation results.