The Coherent Networking Allows Higher Transmission Data Rate

Published:2011/7/14 3:34:00 Author:Phyllis From:SeekIC

The requirement for telecommunications operators that carry more data at cost has been increased so fast that the pressure is growing on companies. To some extent, it’s like the old story happened in every other area of the electronics market, but in this instance, it involves a much larger scale. Particular attention is focusing on fiber optic communications, used primarily for long haul telecom link, but finding increasing application over shorter distances.

One of the reasons is the exponential growth of the data being handled. Theoretically, Telcos can solve this problem by moving to higher data rates, and this could be done by switching from 10 to 40 and even 100Gbit/s. However, if the signals passed over old fiber too faster, they might degrade rapidly as data rate increase.

One solution is coherent networking. Coherent networking technology was actively investigated in the late 1980s and early 1991s in order to improve reach. Its requirement for innovations delayed due to the appearance of wavelength division multiplexing and erbium doped fiber amplifiers which met the need for immediate capacity improvement and reach extension for 10G networks. This technology technology improves the quality of transmitted signals by increasing their spectral efficiency. The DSP technology that enables this can also eliminate a range of equipment deployed along the fiber link.

The POLO 40G will enable equipment developers to take coherent networking away from niche deployments, where it has only been used on the most important routes, to something that can be deployed broadly. POLO enables the two or three slots needed by non coherent equipment to be collapsed to single slot. This is the most challenging area.

Carriers can see clear value in coherent networking because it eliminates a whole class of optical impairment equipment. With non coherent networks, a lot of equipment have to be put in the ground. Coherent transmission means no capital or operational costs.

The non coherent transmission will be phased out quickly. Capacity is important as it brings more options for shorter range metro networks. If the rate increases, the symbol rate also will increase. Coherent transmission increases the amount of information transmitted per symbol so, instead of relying solely on amplitude, you can also include phase information. The key to the development of POLO 40G is the availability of 40nm cmos technology. It enables low power solutions that can be air cooled and it’s 16W power consumption silicon supplier of such technology, which enables existing networks to be upgraded while controlling costs.

The overall result is that, by adopting a coherent networking strategy, optical impairment is moved into the electrical domain, which means the power of Moore’s Law can be brought to bear. The related integrated circuit is BGY588N.

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