Analysis on the effect of transmission power applied to small cells in LTE-advanced downlink

In order to cope with huge mobile data traffic, 3GPP (3rd Generation Partnership Project) has started to discuss the architecture and optimization of a network that introduces a large amount of small base stations (small cells) with higher frequency bands into the area covered by macro base stations (macro cells) with lower frequency bands. In such a network, spectral efficiency will be degraded because of the inter-cell interference among small cells. Therefore, it is important to clarify how much the transmission power of small cells is required to decrease inter-cell interference. This paper presents throughput performances as a function of small cell transmission power for two deployment scenarios. The first is the “co-channel scenario,” where the same frequency bands are shared by both macro and small cells. The other is the “dedicated channel scenario,” where the frequency band of macro cells is different from that of small cells. The numerical results showed that especially the cell-edge user throughput decreases significantly as the transmission power of small cells decreases. In addition, the co-channel scenario outperforms the dedicated channel scenario regardless of the transmission power of small cells, however, higher cell-edge user throughput can be achieved in the dedicated channel scenario compared to that in the co-channel scenario when the traffic offloading technique is introduced.