A femtocell power control scheme to mitigate interference using listening TDD frame

Due to the rapid growth of indoor wireless communications, many of the telecommunication industries recently are interested in femtocell. Femtocell is low power and low cost indoor base-station to cover indoor traffics. Before using femtocell in current wireless environments, interference problem between macrocell and femtocell should be solved since the interference affects the performance of both macrocell and femtocell. In order to reduce the interference, in this paper, we suggest a new time-division-duplex (TDD) frame structure called listening-TDD frame (LTDDF) for femtocells. In LTDDF, femtocell has both downlink and uplink periods during downlink period in macrocell. The uplink period in macrocell is used as listening period in femtocell that is used to overhear signals from surrounding macrocell users to obtain their channel quality information (CQI). Based on the CQI of macrocell users, femtocell base-station adaptively adjusts its transmission power. Thus, LTDDF can effectively reduce interference on macrocell users. By simulations, we evaluate the performance of LTDDF in terms of capacity of macrocell and femtocell in both downlink and uplink.