Research On Intercell Interference Coordination In LTE-Advanced Heteregenous Networks

Interference is an inherent problem in communication systems. As a main technology of 4G, LTE-Advanced requires higher resource utilization, hoping to use a frequency reuse factor close to 1. So inter-cell interference problem needs to be solved. Heterogeneous network is one of LTE-Advanced important technologies. It introduces low-power nodes into cellular systems, creating different kinds of overlapping small cells. In a heterogeneous network environment, due to the complexity of the system, interference problem is more serious, and need more effective interference management.This dissertation gives a general introduction about the architecture and key technologies of LTE/LTE-Advanced system. For LTE-Advanced heterogeneous network interference problems, it analysis a variety of interference scenarios, and focuses on Picocell range expansion technology and time domain interference coordination technology, e ICIC. Simulation is carried out under standard scenarios about these topics. With the anlyses, A new time domain interference coordination scheme based on e ICIC is presented under Macro-Pico-Femto coexistence scenario. By reserving some orthogonal time slot resources, the complex interference problems under this scenario is addressed. Theoretical analysis shows that Macrocell edge users and users in expanded range, which performance bad in system, get their throughput improved with only a little loss of other users. Simulation based on an open-source tool, LTE-Sim verifies this result.For frequency domain interference coordination, this article analysis Fractional Frequency Reuse and Soft Frequency Reuse, as well as FFR-3. On this basis, a new schema based on Fractional Frequency Reuse is proposed to address the inteference problem under Macro-Femto coexistence scenario. Based on FFR-3, the cell is divided as center and edge, and it is also divided into 6 sectors with bandwidth divided accordingly. Interference problem under this scenario is solved by allocating suitable frequency bands for Femtocell. Theoretical analysis and simulation show that while throughput of Macrocell users in cell center remains unchanged and Femtocell users in cell center declines, throughput of the rest u sers is improved.