Viscore

For the FTTx market, the GEPON, GPON, 10GEPON seems the roadmap for coming five (5) years.What will happend after that? WDM-PON seemed the only available solution. But, someone is aksing "How about 40gPON?"

Viscore is seriously checking the feasibilty of the 40GPON solution. An initialitive R&D program is addresseing this question.  NSN shows strong intereste in that question too. But they concluded, quite early, that is the answer already.

Coherent receivers in the access?

by Stephen Hardy
Editorial Director and Associate Publisher, Lightwave
September 27, 2011

Nokia Siemens Networks hasn't been very active in the PON space recently, but that doesn't mean it doesn't have plans for the access niche. In fact, the company has some aggressive technological ideas it hopes to implement -- including coherent receivers.

A pair of Nokia Siemens Networks sources at the WDM-PON Forum in Orlando today discussed the company's plans -- which, appropriately enough, involved WDM-PON. Or, more precisely, ultra-dense WDM-PON, with the ability to support up to 1,000 wavelengths. Nokia Siemens Networks has some advanced optical technology in mind for its Paired Channel Technology, including laser sources capable of transmitting multiple wavelengths that create optical transmission groups. The OLT, of course, transmits in the downstream direction and the ONTs transmit a complementary upstream signal offset from the downstream signal by 1 GHz.

But it is the planned use of coherent receivers that raised eyebrows in the room. Coherent technology, of course, is the most widely adopted approach for long-haul 100-Gbps DWDM networks, paired with dual-polarization quadrature phase-shift keying (DP-QPSK). Like any emerging technology, it's expensive in its present incarnation. But it won't be too expensive to be used to extend WDM-PON transmission reach up to 100 km, Nokia Siemens Networks believes. The sources pointed out that both the optical and electronic/DSP requirements for 1 Gbps over 100 km won't be nearly as complex as the long-haul technollgy now reaching the field. The relaxed requirements will lead to much lower price points that will be within reason for access networks, the sources said.
Nokia Siemens Networks has already demonstrated the full ultra-DWDM-PON technology in its labs. But the technology is probably several years away -- think the 2014/2015 timeframe -- from reaching commercialization.