A link adaptive scheme for multihop cellular systems using congestion feedback

LTE-Advanced standards contemplate support for heterogeneous networks, through the use of relays, as well as the ability to perform carrier aggregation in order to achieve higher data rates. In this paper, we model the User Equipment's (UE) ability to select its current point-of-access to the network (either a relay or the base station), aggregate additional channels, and perform power adaptations. The adaptations by UEs affect one another, by impacting the interference conditions in the network as well as congestion conditions in the relay-to-base station links. We propose an adaptation mechanism whereby the UEs consider these factors and select their transmit power, channels, and point of access to the network to optimize a combination of achieved data rate and energy consumption. Our results show these adaptations to be more efficient than adaptations that simply consider current channel quality indicators, combined with greedy channel aggregation.