Presently, telecommunications networks are designed to handle the peak loads and little consideration is given to medium and low load situations. Designing adaptable net-works, which are able to switch off elements when the demand is lower, will lead to networks that consume less power.
In core networks this can be achieved with dynamic topology optimization. This means that from the multiple possible topologies that satisfy the traffic demands, the topologies with lower overall power consumption should be preferred. Dynamic optimization typically exploits the daily or weekly alternations in traffic load, where off-peak volumes are potentially lower than 50% of peak volumes. When employing multilayer traffic engineering (MLTE) and changing the MLTE strategy to optimize towards power consumption, reductions of more than 50% during off-peak hours can be achieved [7].MLTE adapts the topology to optimize for power consumption, thereby increasing the number of inactive line cards, which can subsequently be switched off and thus save power.
In fixed line access networks, a similar strategy is possible by using Dynamic Bandwidth Allocation (DBA) in PONs. DBA is currently used as a way to allow users to have increased bit rate while other users on the same medium require less bit rate. The same strategy could also be used to create dynamically adaptable OLTs which utilize less ports on which a higher split ratio is applied during periods of low traffic. This allows elements to be switched off in the OLT and leads to a reduced power consumption.
In wireless access networks optimization can be achieved by the utilization of hybrid hierarchical base station deployment. When using base stations with differentiated cell sizes and wireless network technologies, a basic access network can be created that provides a low bit rate but high coverage to the users. In the hierarchical layers above, base stations with smaller cell sizes but higher bit rates can be utilized to provide the high bandwidth connections when these are needed. The advantage is that the higher layers can be put to sleep and only need to be activated with high traffic demand.
For example, LTE-Advanced, the successor of LTE which is under development will support advanced repeaters. Repeaters are active elements without full base station capabilities. Currently, repeaters are designed as always-on devices. However, in LTE-Advanced the transmission power of these repeaters will be controled by the network and activated when users are present in the area handled by the repeater.