The main advantage of software-defined visible light communication (VLC) systems is that they allow us to reuse modulation, coding, synchronization and medium access techniques used in conventional radio systems. This article focuses on the implementation of an uplink alternative using an infrared (IR) light communication system. For this goal, analog front-ends are designed and implemented. Therefore, they convert a radio frequency signal into an optical signal. In addition, a Universal Software Radio Peripheral (USRP) is used as a software-defined radio platform. The obtained bit error rate is 5.33 × 10−5 using QPSK modulation with a bit rate of 4 Mbps at a distance of 160 cm between transmitter and receiver.