Abstract:The overlapped deployment of heterogeneous cells brings new challenges into inter cell interference coordination (ICIC), while the enhanced ICIC techniques, such as cell range expansion (CRE) and almost blank subframe (ABS), are considered as effective techniques for solving related issues, but their performance is not extensively explored. Uplink CRE scheme and downlink ABS based CRE scheme are focused on, and it is found that the CRE technique could distinctly improve uplink performance. However, downlink performance may be severely impacted if the downlink of a picocell is identically expanded as its uplink. To solve the problem, the ABS based CRE scheme is investigated for downlink and it is found that the joint optimization of CRE and ABS could effectively improve the downlink performance. Results show that Max Min fairness can be obtained by appropriate settings on CRE bias and ABS ratio.