A non-cooperative method for path loss estimation in femtocell networks

A macrocell superposed by indoor deployed femto-cells forms a geography-overlapped and spectrum-shared two-tier network, which can efficiently improve coverage and enhance system capacity. To reduce inter-tier co-channel interference, femtocell user should choose suitable access channel according to the path losses between itself and the macrocell users. Path loss should be estimated non-cooperatively since information exchange is difficult between macrocell and femtocells. In this paper, a novel method is proposed for femtocell user to estimate the path loss between itself and any macrocell user independently. According to the adaptive modulation and coding (AMC) mode information broadcasted by the macrocell base station (BS), femtocell user first estimates the path loss between BS and a macrocell user by using Maximum a Posteriori (MAP) method. The probability density function (PDF) and statistics of the transmission power of the macrocell user are then derived. According to the sequence of received power values from the macrocell user, femtocell user estimates the path loss between itself and the macrocell user by using minimum mean square error (MMSE) method. Simulation results show that the proposed method can efficiently estimate the path loss between any femtocell user and any macrocell user in various kinds of conditions.