Implementation of LTE Uplink system for Software Defined Radio Platform using CUDA and UHD

Abstract

It was demonstrated in [1] that SDR (Software Defined Radio) platform can be implemented on a normal PC (Personal Computer) together with USRP2 (Universal Software Radio Peripheral 2) board which adopts GNU radio for its RF function block libraries and CPU (Central Processing Unit) for its software modem. In this paper, we present a novel implementation of SC (Single-Carrier) - FDMA (Frequency Division Multiple Access)-based LTE (Long Term Evolution) uplink system, i.e., 3GPP (3rd Generation Partnership Project) Release 9 standard, on a SDR platform using a conventional PC, which adopts GPU (Graphics Processing Unit) instead of CPU and USRP2 boards with UHD (Universal Hardware Driver) instead of GNU radio for SDR software modem and RF transceiver, respectively. Hardware of USRP has originally been designed for supporting GNU radio which is a software tool for runtime signal processing. Noting that USRP hardware can be interfaced with customized C++ code by using UHD, we have adopted UHD instead of GNU radio in order to achieve a lot higher degree of flexibility in the design of transceiver chain. In addition, UHD also provides a lot wider set of Application Programming Interfaces (APIs) for interfacing the host computer with the USRP2 board compared to GNU radio. Meanwhile, in order to cope with an extremely high-speed data rate in modern communication systems, the processor for SDR-based signal processing should support the high system throughput and high operation speed. Although multi-core CPU in PC could also be substituted for the DSPs and FPGAs, it would decrease the speed of the other tasks originally assigned to the CPU of the computer. Considering that GPU is suitable for parallel computing due to its powerful arithmetic logic units, software modem in our system is implemented on GPU board. We implemented LTE Uplink system using GPU and USRP2 with UHD. The video streaming data, which are given in accordance with the 3GPP standard of LTE Uplink frame, are sent to the USRP2 by the UHD at the transmitting mobile terminal. The USRP2 hardware performs digital frequency-up conversion and RF conversion before sending the samples over the air. In the receiving base station, the reverse operations are performed using GPU and USRP2 with UHD. We demonstrate real-time performances of our implemented system. Experimental results such as BER (Bit Error Rate), FER (Frame Error Rate), throughput, etc will be presented and compared to computer simulated performances.