Femtocell as a relay with application of physical layer network coding
This paper is concerned with the dead zone problem of uplink communication in two-tier femtocell network. In the uplink communication, the interference generated by a macrocell user at the edge of the macrocell base station (MBS) coverage area may cause the signal-to-interference-plus-noise ratio (SINR) received at the nearby femtocell base station (FBS) below the requirement, and the region in which the nearby FBS can not meet its SINR requirement is called a Femtocell Dead Zone (FDZ). In order to guarantee the quality-of-service (QoS) of macrocell users and femtocell users, the transmission power of femtocell users should be controlled properly. In this work, the uplink interference scenario that exists between a femtocell and a macrocell is modeled and discussed in detail, and then, the fundamental limit of the achievable SINR at MBS and FBS is shown. Numerical results present a straightforward way to establish the FDZ and show the impact of the uplink interference from macrocell user on the QoS of the nearby femtocell user.