LoRa is one of the mainstream alternative technologies of Low-Power Wide-Area Network (LPWAN), which employs Differentially Bi-orthogonal Chirp Spread Spectrum(DBO-CSS) as its physical layer modulation. Rapid timing acquisition and reliable receiving in low SNR are the two most important issues when applying DBO-CSS in typical Internet of Things(IoT) scenarios. Therefore, a LoRa system supporting multi-user access is built utilizing the Universal Software Radio Peripheral(USRP) of NI Company. And two essential technologies including synchronization algorithm based on improved matching filter and diversity scheme based on 2D-Rake receiver are proposed and verified by simulation and experiment on this system. The results indicate that the improved synchronization algorithm has better performance in accuracy and the 2D-Rake receiver can provide 3 dB of gain in SNR.