A New Approach in LTE-A Downlink Power and Transport Block Management

In this paper, we present a new approach that seeks reducing the downlink TBS-index by the LTE-A eNodeB. Our objective is to minimize the total transmitted power based on getting the benefit from available but unused PRBs, while considering the QoS for the UEs and mitigating the interference from adjecent eNodeBs. Most previous studies have not assigned the residual PRBs in the eNodeB to change the MCS order in the context of TB. Also, they have not considered the TBS-index as a constraint. In this paper, we formulate a new downlink assignment problem that takes the TBS-index into account, where the PRBs are selected for each TB based on the total available but unused PRPs and the CQI of each UE. Controlling the TBS-index while increasing the number of PRBs will have an effect on the MCS order, hence reducing the transmitted power with respect to the positions of UEs. The TB corresponding to using one MCS and one CC is implemented to enhance the throughput of a generic system with the SISO mode and the infinite buffer traffic type. The proposed approach consists of two aspects: (1) exploiting the residual PRBs among multiple UEs to reduce the TBS-index, (2) finding the optimal power allocation for each UE regarding the optimal MCS, relating to the required throughput, as well as the current channel state information of each UE. The proposed approach is implemented with a greedy algorithm. A set of comprehensive simulations is conducted. It is shown that our approach has made several improvements to the conventional approaches.