Study On The Interference Coordination Of Small Cell For LTE-Advanced And Its Key Technologies

Currently, Long Time Evolution-Advanced (LTE-A), which is proposed and driven by the3rd Generation Partnership Project (3GPP), has become a widely used standard of4th generation mobile communication. A series of new technologies are applied into LTE-A system, such as Enhanced Uplink/Downlink Multiple-Input Multiple-Output, Carrier Aggregation, Coordinated Multi-Points transmission and reception, Relay, etc. Compared to the former mobile communication systems, LTE-A system has improved significantly in terms of frequency efficiency, system bandwidth, peak data rate, etc. Though LTE-A is now the fastest evolving mobile communications technology in the world, it has to overcome the new challenges one by one. With the rapidly growing demand of mobile communication users, Small Cell becomes the first choice of the telecommunication operators and equipment venders to satisfy the users’ demands. Small Cell Enhancements (SCE), which has received a lot attention from the communication industry, is expected to be written into3GPP Release-12specification. Small cells are low-power wireless access points that provide improved system capacity and user experience for homes and enterprises as well as metropolitan and hot spot spaces. The deployment of Small Cell brings us new opportunities as well as new challenges. The wide deployment of Small Cell will increase the coverage of the inter-cell overlapping area. LTE-A usually uses the same frequency mode to increase the frequency efficiency. The larger the inter-cell overlapping area is, the stronger the inter-cell interference will be. In order to reduce the inter-cell interference, some technologies have be adopted into LTE already, such as fractional frequency reuse, soft frequency reuse, etc. But when these technologies are applied into Small Cell scenarios, there is no significant gain and it is very difficult to apply them into Small Cell scenarios successfully.3GPP introduced a new interference coordination technique which is called enhanced Inter-Cell Interference Coordination (eICIC). eICIC is a time domain solution which usually applied with Cell Range Extension (CRE). They can offload users into Small Cell and improve the Signal to Interference plus Noise Ratio (SINR) and system performance. The thesis introduces a new carrier type, called NCT. The rational designed NCT can reduce the reference signals’overhead of the original carrier type, as a result, it can reduce then energy consumption, improve the resource utilization, reduce the inter-cell interference and access a gain of system performance. However, Release-8users cannot work properly with NCT as a result of CRS reduction in NCT. That is to say NCT is not backward compatibility. NCT need to be carefully considered in the3GPP standardization process.In order to accurately assess the performance of new technical solutions, the paper adopts a LTE-A system-level simulation platform according to3GPP SCE scenario. Firstly, the paper introduces eICIC into SCE scenario, analyzes the system performance and then gives out the optimal allocation of eICIC in SCE scenario. The paper also introduces the details of NCT and gives out the interference cancellation gain and overhead reduction gain of NCT through theoretical analysis and system-level simulation, showing that NCT can provide a significant gain in macro-only and SCE scenario.