Energy saving potential of cyclic sleep in optical access systems

Energy efficiency has become an increasingly important requirement in designing access networks, both due to increased concerns for global warming and due to increased network costs related to energy consumption. In comparison to the metro and core segments, the access constitutes a substantial part of the per subscriber network energy consumption and is regarded as a bottleneck for increased network energy efficiency. One of the main avenues for reducing network energy consumption, and subject to intense research, is the introduction of load adaptive techniques where network elements/subsystems are powered off during periods of reduced network load. Such techniques are particularly interesting for the access segment which is characterized by low utilization. The combination of large contribution to the overall network power consumption and low utilization implies large potential for exploiting such load adaptive techniques. In this article we develop a framework for estimating the energy saving potential of cyclic sleep in access, given the constraints from service requirements and traffic conditions. A few critical components are considered and used for showing the potentials for cyclic sleep in optical access networks