Telecom Lead India: Telecom service providers are now beginning to migrate from 10G to 100G. Andrew Bond-Webster, vice president, Asia Pacific, Infinera, shares several optical networking challenges in the Indian telecom market.
The need for ever-increasing bandwidth capacity shows no sign of decreasing. With the number of devices used to connect increases exponentially, service providers need to ensure the backbone infrastructure is capable of handling this demand. In India, this data usage continues to grow and network service providers aim to offer the best price to gain maximum share in the market. There is also a need to connect rural areas to efficient infrastructure that does not require high maintenance as fibre optic cables can get easily damaged and connectivity could get disrupted. At the same time Service Providers require the infrastructure build-out to be speedy to address unmet demand in urban centers beyond just the top ten cities.
Despite the global recession, the internet demand continues to grow. To cope with this increase in demand, service providers have to “do more with less” – they try to slow down capital spending but cannot risk delivering low performing networks as users will simply move to a different service provider.
Optical transport networks are composed of two layers: SONET/SDH and DWDM. Each provide a diverse but balancing set of qualities and challenges, which helps service providers offer extensive service features and network functionality, but requires them to spend considerable effort to plan and optimize their network architecture. The industry is now going through an “Optical Reboot”. There is acceleration in the trend away from SONET/SDH to DWDM optical equipment in the US and China, and a similar transition in EMEA. The shift towards next generation mobile backhaul infrastructure is one factor, carriers are also preparing for the optical reboot, which is a rebuilding of core networks to use 40/100G, OTN, and ROADM technologies. Within India, operators are now leapfrogging with newer technologies for core transport networks thus jumping over the “Reboot” stage.
The optical technology is moving to coherent detection, which delivers roughly ten times increase in optical capacity over the same fiber infrastructure. A special form of this coherent detection is known as a “super-channel”. A super channel is an evolution of DWDM technology in which several optical carriers (or lasers) are combined to create a composite signal of the desired capacity. Some of the advantages of super channels instead of simply sending multiple wavelengths down a fiber are:
The spacing of optical carriers within a super channel can be reduced considerably compared to the ITU-T WDM grid, this enables higher spectral efficiency, which is a key driver for using super channels;
Super channels behave as a single unit of bandwidth, are brought into service in a single operational cycle, and therefore allow service providers to scale operations without scaling costs.
Super channels enable the industry to get to higher bit rates five or even 10 years sooner than would be possible with single channel technology.
Even on the optics side there are economic and time-to-market advantages in using super channels.
The best way to implement a super-channel would be to use an advanced optical chip such as a “photonic integrated circuit” (PIC). A PIC has ten optical signals implanted on a tiny chip that is about the size of a thumbnail – but it can transmit 500Gb/s of long haul optical capacity. A PIC is conceptually very similar to an electronic IC. The latter integrates transistors, capacitors and resistors while a PIC integrates multiple optical components such as lasers, modulators, detectors, attenuators, multiplexers/de-multiplexers and optical amplifiers. Like their electronic counterparts, large-scale PICs extend the scope of integration so that upwards of dozens or more distinct optical components are integrated into a single device. In a hybrid PIC, multiple single-function optical devices are assembled into a single package, with associated electronic ICs, and are inter-connected by electronic and/or optical couplings internal to the package. Today, many integrated photonic devices available employ hybrid integration to consolidate packaging.
PIC-based super-channels address the critical issues of “Total Cost of Ownership” (TCO) of a Transport Network. Capital cost of the equipment is not the only reason for TCO; the total lifetime cost is another reason. As bandwidth grows exponentially in India, operators are increasingly being challenged to keep the TCO low. They are looking at network architectures that reduce power consumption and rack space while increasing efficiency through higher wavelength fill. At the same time, regular fiber cuts across the landscape require operators to seek the most reliable solution while enhancing spares management.
Core networks are in the center of transforming to dramatically increase capacity while maximizing the efficiency of transport to reduce the cost per bit. Providers are now beginning to migrate from 10G to 100G.
While the industry is continuing to grow, service providers now have scalable and cost efficient solutions to cater to their requirements. Super-channels will continue to be developed and the industry can look forward to a move from fixed grid architecture to flexible grid architecture. There is also continuous effort in integrating the bandwidth management to combine both optical super-channel switching and OTN switching. Integrated OTN switching is also being developed. A greater importance will be given to automated control planes such as distributed control planes in the form of GMPLS and Centralized control planes in the form of the Software Defined Network. The future of optical networking has a lot of potential and research and development will continue as the demand for bandwidth is growing at an exponential rate.
Andrew Bond-Webster, vice president, Asia Pacific, Infinera
editor@telecomlead.com
