Commercially deployed coherent system for video distribution

Abstract

A commercial video distribution system established on the FTTH network in Japan is described. The key to commercial deployment is FM conversion of multichannel FDM video signals by means of an optical heterodyne technique.

Frequency-Multiplexing Transmission of Video and Wireless Signals Utilizing FM Conversion Method

“…2) uses the frequency modulation conversion (FM conversion) method [7]. Although the FM conversion method has a more complicated configuration than the intensity modulation method, it has the advantage of being highly noise-resistant, thereby ensuring highquality transmission over long distances [8]. Taking advantage of this characteristic, we were able to successfully transmit a total bandwidth of 3.…”

Optical coherent technologies in next generation access networks

“…Clipping noise due to direct modulation of laser diodes (LD) [8] 3. Degradation of optical reflection induced at mechanical splice points [9] 4. Distortion of RF signal due to fiber dispersion [10] Table 1 summarizes the countermeasures with devising transmitters (Tx) and receivers (Rx) of RoF system.…”

“…The other techniques in Table 1 mitigate the impact due to the technical issues by introducing the optical coherent technologies. The technique 2 reduces the impact due to the technical issues 1, 2, and 3 with FM modulation of LD and heterodyning detection, which converts multicarrier AM signals to FM signals [9]. This technique can be applied to OFDM RF signals to reduce the intermodulation distortion, clipping noise, and impact of optical reflection, as well.…”

“…Figure 3 shows the commercially deployed FTTH system configuration. The GE-PON system (IEEE 802.3ah) consists of GE-OLT and GE-ONU, and provides voice and data communication services [9]. In the video distribution system, multichannel video signals from the head-end are E/O converted in the transmitter and relayed by V-OLTs.…”

“…The wavelength allocation is, in compliance with recommendation ITU-T G.983.3, 1.49μm and 1.31μm for downstream and upstream, respectively, in the GE-PON system, and 1.55μm in the SCM-PON system. ) show the configurations of video distribution system with the FM conversion system [9] and the conventional SCM, respectively. The difference between two systems is that the FM conversion system has an FM converter in the video transmitter and an FM demodulator in the V-ONU.…”