Developing tomorrow’s network today

A major evolution in the way in which services are provisioned is now taking place in the communications industry.

Traditionally, services have been associated with a location, a type of terminal, and a given access technology (for example, groupware installed on an office computer that’s connected to a LAN; analog television received on a home TV set connected to a terrestrial antenna; voice services as far as signal can be received from the closest GSM antenna, etc.). The process of moving towards ubiquitous service availability and a global seamless mobility of services across different frontiers-including types of terminals, technologies, and administrative domains-has begun.

Moreover, services are converging. The fixed and mobile convergence that we see today is just a first step towards a world in which service components offered by different providers will be dynamically associated to create personalised services. Such personalised services will be both location and context-aware, and they will be ubiquitous. This goal will be supported by a variety of access technologies, among which are xDSL, FTTX, wireless (Wi-Fi, WiMAX), cellular (2G, 3G, and beyond), satellite, cable, and so on.

As far as the user is concerned, this diversity will be transparent; in order to reduce costs, those technologies will be backhauled over a reduced number of virtualised infrastructures based on a small number of technologies. This will give rise to new business models between service and network providers. Management of these architectures will become increasingly complex; that will impose new paradigms for managing the network, which will include adaptive local self-reconfiguration based on the information obtained from advanced monitoring approaches, without requiring centralised decisions. Traffic flows will be treated in a more intelligent fashion than current schemes of prioritisation and separation provide.

Self-organisation, for example, allows Wi-Fi access points to discover each other and spontaneously create a network. Using this approach, only a few access points need to be connected to the Internet to cover an entire neighbourhood, since a self-organised network will provide the required coverage. The last mile, once the sole domain of the operator, will therefore eventually fall under the control of the end user, while the service provider offers integration and operation, administration, and maintenance facilities for interconnecting networks of networks.

But the future promises an even greater expansion of heterogeneous network presence as more and more objects begin to communicate with each other in the public space. Every electronics gadget in the environment will have a radio link to provide identification and location information, transmit sensor data, and receive control signals. An Internet of objects will be born.

This process will significantly affect the various technologies that will have to interwork, control and management approaches, and traffic structure. Driven by ubiquitous service delivery and heterogeneous network presence, compounded by the proliferation of private network entities, tomorrow’s access networks will require an exponential increase in backhaul capacity. Solutions to achieve this at cost and performance levels that simultaneously ensure profitability and customer satisfaction can only be provided by vendors familiar with the entire spectrum of technologies that networks will be called upon to support.

Several of the changes we envisage inevitably lead to a requirement for increased capacity in access networks. The rising demand for bandwidth will come from residential customers and businesses alike. The services offered will also require an increase in core, metro, and cellular backhaul network capacities.

An obvious way to ensure that the need for more bandwidth is met is for carriers to increase their provisioning of fibre to the home (FTTH) and fibre to the office (FTTO). The relative difference in cost between fibre and copper infrastructure has dropped significantly in recent years, to the point where fibre is becoming able to give copper a run for its money. The increased capacity that will be required, however, can only progressively strengthen the case for FTTH and FTTO over copper in any future cost-benefit analysis. The advent of inexpensive plastic optical fibres, which allow 100 Mbit/s bidirectional transmission over 300 m, will further accelerate this trend.

Another reason why fibre will eventually become a cost-effective replacement for copper at the home and office might very well turn out to be the proliferation of passive optical networks (PONs), a high-bandwidth, passive point-to-multipoint optical architecture. PONs divide wavelengths of light into timeslots so that each wavelength can be shared by a number of users. This is accomplished by using passive devices to split the optical signal and PON protocols to control the traffic across the shared access facility. In this way, a single fibre from the carrier’s exchange can be shared by separate final users, drastically reducing the costs of provisioning FTTH and FTTO. WDM-based next-generation PONs (often called “Super PONs”), which are able to extend coverage to thousands of users within a 100 km radius, will simplify access networks and central office architectures.

Meanwhile, even newer optical networking technologies are waiting in the wings. Optical burst switching, for example, promises even greater improvements in wavelength utilisation, although so far there is no clear business model for these technologies on a network scale (the technology is being used to build very high capacity routers).

Next-generation optical networks will require the flexibility introduced by evolved management and control planes, providing, for example, a better interaction with upper layers, including multilayer routing, protection, and restoration. These innovations will lead to a reduction in capital and operational expenses for carriers, which can then be passed on to the consumers of tomorrow’s ubiquitous services.

Daniel Kofman is chief technology officer at RAD Data Communications

Lightwave Europe May, 2007

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