Subsea Cables & Internet Infrastructure

Benoit Kowalski gave the presentation at the event. The diagram below shows the standard subsea network architecture. The fibre optic cable and optical amplifiers are collectively called the wet segment. The rule of thumb is to bury the cable in waters a thousand meters or less deep. Approaching shore one has a choice. One can give bring the cable ashore using small boats. The cable initially lies exposed on the beach up to the beach manhole. Then the cable is buried from some point in the water up to the manhole where it is spliced into the front haul fibre that carries the signal to the cable landing station. From the CLS back haul fibre goes to a carrier neutral data center that serves as a point of presence (POP) or interconnection point. The other platinum-plated approach uses horizontal drilling to install a bore pipe from the manhole to a point on the sea floor offshore. This is much more expensive, but better protects the cable.  A couple of things to note. I...

Dr Kowalski is a Nokia employee who collaborates with ASN. His presentation on the first day of the conference is a good subsea cable primer.  The transmission equipment is known as the submarine line termination equipment or SLTE. It has three key components. Encoding involves taking the digital input and converting it into a series of laser commands according to the modulation scheme. FEC or forward error correction adds redundant bits called parity bits that help the far end FEC to detect and correct payload mistakes. It is a bit like a router creating the checksum field in the IP packet header. Once quality is control is completed, the laser sends the optical signal. Its ever weakening light travels the fibre until it is passively boosted by erbium doped fibre in the amplifier that has been raised to a high energy level by pump lasers. At the far end of the linear transmission the steps are reversed. The optical receiver takes the light signal and converts it into the appropria...