Spectrum Allocation for ICIC Based Picocell
  In this work, we analytically study the impact of spectrum allocation scheme in picocells on the coverage probability (CP) of the Pico User (PU), when the macro base stations (MBSs) employ either fractional frequency reuse (FFR) or soft frequency reuse (SFR). Assuming a fixed size for the picocell, the CP expression is derived for a PU present in either a FFR or SFR based deployment, and when the PU uses either the centre or the edge frequency resources. Based on these expressions, we propose two possible frequency allocation schemes for the picocell when FFR is employed by the macrocell. The CP and the average rate expressions for both these schemes are derived, and it is shown that these schemes outperform the conventional scheme where no inter-cell interference coordination (ICIC) is assumed. The impact of both schemes on the macro-user performance is also analysed. When SFR is used by the MBS, it is shown that the CP is maximized when the PU uses the same frequency resources as used by the centre region. 
Suman Kumar, Sheetal Kalyani, K. Giridhar
cs.IT math.IT