Relay placement for inter-band carrier aggregation with asymmetrical coverage

Relaying and carrier aggregation are two main features of Long Term Evolution Advanced (LTE-A) that improve the transmission and increase the capacity of the network. Besides, enhance the overall capacity inside the coverage area of a relay. A relay can be used to solve the problem of capacity fairness for non-overlapped region produced by the lower frequency component carrier in inter-band carrier aggregation. This paper proposes a new approach of relay placement to enhance the capacity of cell edge user in inter-band carrier aggregation scenario with asymmetrical coverage. A simulation model for LTE-A in the downlink has been developed to investigate the impact of relay placement. The simulation result shows that a relay can be placed inside the overlapped coverage region to enhance the capacity of the cell edge user. The study suggests that for average cases a relay should be placed closer to the middle of the cell produced by lower frequency component carrier. For extreme cases with higher path-loss exponent and for larger interband gaps, the relay should be placed closer to the cell edge. Furthermore, the optimal position of the relay is closer to the cell edge when the link budget of relay is much smaller than the eNodeB (eNB).