Frame alignment and interference cancellation strategies for cell search in HetNets

In a heterogeneous cellular network(HetNet), the mobile terminal (MT) receives the superposition of transmit signals from different BS in its vicinity. Because of the inherent transmit power difference of different kinds of BS(macro,femto,pico) and due to near far effect, the MT encounters strong interference from neighbouring BS. Every BS sends a known training signal (synchoronization signal) to enable the MT to perform necessary physical layer operations and decode relevant information for further communication. The synchronization signals are unique to every BS. In this paper we consider the problem of a MT synchoronizing to a BS, whose received power is relatively weak and the MT encounters a strong interference from another BS. For this we propose different alignment methodologies for the location of training signals of strong power BS and weak power BS in their respective frames. We show that when these two training signals corresponding to strong and weak BS have an offset in time equal to half the training signal duration, the detection performance of weaker BS can be significantly improved.