Joint optimization of uplink power control parameters in LTE-Advanced relay networks

Relaying is a promising enhancement to existing radio access networks and is currently being standardized in 3GPP to be part of the LTE-Advanced Release 10. Relays promise to alleviate the limitations of conventional macrocell-only networks such as poor indoor penetration and coverage holes in a cost-efficient way. Yet, to fully exploit the benefits of relaying, the inter-cell interference which is increased due to the presence of relays should be mitigated. Besides, a high receiver dynamic range should be avoided to retain the orthogonality of the SC-FDMA system. In this manner, uplink power control is an effective tool to address such challenges. However, in order to enhance the overall system performance, power control optimization should be jointly done on all links, i.e. on eNB-relay node, eNB-UE and relay node-UE links. In this paper, we propose a joint optimization strategy of power control parameters based on Taguchi´s method that exploits the mutual dependencies of the different links without a priori knowledge. The proposed joint parameter optimization is compared with a reference study that comprises a four-step optimization. The evaluation of the optimization strategies within the LTE-Advanced uplink framework is carried out by applying the standardized LTE Release 8 power control scheme both at eNBs and relays. Simulations show that the proposed optimization yields similar or better performance relative to the reference strategy depending on the considered performance metric.