Improving spectral efficiency of digital radio-over-fiber transmission using two-dimensional discrete cosine transform with vector quantization.

Radio-over-fiber (RoF) transmission is a quite reliable technology to support the current and future demands of rapidly progressing broadband wireless network with large capacity and high spectral efficiency. In this paper, we report and demonstrate a digital RoF transmission system using two-dimensional discrete cosine transform with vector quantization (2D-DCT-VQ). By employing the 2D-DCT-VQ technique, the spectral efficiency can be greatly improved, while the system performance is comparable to the traditional approach without compression. The proposed method is experimentally demonstrated in a 20-km 5-Gbaud/λ four-level pulse modulation intensity-modulation/direct-detection optical link. In the orthogonal frequency-division multiplexing -modulated downlink illustrated experimentally, the transmission rate rises by 69.49% on account of the compressed samples by using the proposed method.