Energy efficient carrier aggregation algorithms for next generation cellular networks

Carrier aggregation (CA) is an important feature of next generation cellular networks (LTE-advanced, LTE-A) that allows its users to aggregate upto 100 MHz of (dis-)contiguous spectral chunks to provide increased data rates. While the conventional approach of allowing LTE-A users to be configured on all component carriers, results in maximum diversity gain for scheduling, it also increases the users' power consumption and processing that scale with the number of component carriers. In light of the growing need to minimize energy consumption on mobile devices, we argue that it is possible to operate the LTE-A users on a small subset of component carriers to reduce their energy consumption, without any appreciable loss to the scheduling gain. A key step in realizing this goal however, is to address the joint problem of component carrier selection as well as scheduling and in turn forms the focus of this work. We highlight the hardness of the joint problem when the number of component carriers that can be activated for an LTE-A user is limited. Towards solving the problem, we consider various models that incorporate both contiguous and dis-contiguous CA as well as backlogged and finite user buffers and propose efficient, greedy algorithms with performance guarantees that are also simple to implement. Our evaluations based on LTE system parameters, reveal that our algorithms help realize 80-90% of the maximum scheduling gain with just half the component carriers and provide a 25% throughput gain over baseline load and signal power based carrier selection schemes.