Transmission Power Control Method Using Protected and Non-Protected Bands Based on Shared Metric among Base Stations for Downlink Heterogeneous Networks

This paper proposes a downlink transmission power control method using protected and non-protected bands, which are assumed in the inter-cell interference coordination (ICIC) strategy, in downlink heterogeneous networks. The proposed method requires inter-base station (BS) cooperation. However, the proposed method can be implemented by sharing only a single metric among BSs, which can contribute to a realistic implementation. In the proposed method, cooperating BSs share the tentative worst user throughput that is observed in the protected band within the cooperating cells. With this information, the transmission power of the protected band of each BS is controlled so that the worst user throughput within a macrocell coverage area is maximized. Different from our previously reported transmission power control method, the proposed method fully utilizes the remaining BS transmission power in the non-protected band. Therefore, the proposed method maintains the average user throughput at nearly the same level as that without transmission power control, while the worst user throughput is significantly improved. Thus, the proposed method enhances the user fairness within a macrocell coverage area. Multi-cell simulation evaluation shows that the proposed method yields advantageous throughput performance compared to conventional approaches.