A new optical network to 160 Gbps
Oki Electric Industry has developed a system of optical fiber that can reach 160 Gbps . According to the company, this is the first passive optical network symmetrical broadband next-generation system using a hybrid OTDM and OCDM which realizes such a performance. The method used by the company is a multiplex that uses the advantages of both the OTDM and the OCDM. Indeed, the OCDM can identify different optical channels but not a sufficient multiplexing because of interference between channels. On the other hand, the OTDM multiplexer effectively allows a lot of information on a temporal division, but does not identify the different optical channels. The hybrid system uses the OTDM to reduce optical interference and to identify channels. Currently, optical networks used by Internet providers are the GE-PON systems (1.25 Gb) in Japan and G-PON (2.5 Gbps) in the U.S. and Europe, including primary function is the transmission of data and video. The new technology is 128 times faster than systems based on the standard GE-PON and 64 times faster than those based on the G-PON. In both systems, where 16 users are connected, the connection is limited to 78 Mbps for GE-PON and 156 Mbps for G-PON, while the connection of a user of the hybrid system is limited to 10 Gbps. A speed of 160 Gbps allows sending, per second, 6 channels of high definition video, uncompressed or 33 channels of compressed high-definition video. Transmit signals as fast over a single optical fiber from the server to users means that video services such as high definition film distribution and application of telemedicine may be offered to users who are connected. The primary equipment used for this system is the optical line terminal that is used in passive optical networks. After the encoding of 10Gbps signals, and optical multiplexing in a time interval (or slot) TDM Oki quadruple the signal wavelength to output a multiplexed signal of 16 channels at 10 Gbps. The 160 Gbps signal is then transmitted over a distance of 20 km and then demultiplex a divisor with 1 x 16. Signals are extracted from the optical network unit and treated to finally decoded signals of 10 Gbps. For this experiment the company has a code-multiplexed in a TDM slot. However, technically the system can multiplex up to four codes in a single time interval. In this case, it can transmit four times more data (64 channels x 10 Gb = 640 Gb). In order to use the resources of wavelength more effectively, the structure of signals 4 x 4 x 1 slots wavelength can also be adopted. These achievements are part of the "Basic Technology Promotion System for Private Sectors" of NICT and more specifically the research and development of passive optical networks asymmetric high-speed next generation.
