Research On The Interference Coordination For Heterogeneous Cellular Networks

The rapidly development of multimedia service has greatly boosted the requirement ofhigh speed data transmission in wireless mobile communication systems. It is also requiredthat the cellular networks must have a larger coverage as the urban population densityincreasing gradually. In LTE wireless network systems, different type of base stations aredeployed to decrease the cellular size in order to get higher spectrum efficiency per unit area.In the novel network model proposed by LTE, multiple base stations can cooperate with eachother in dense residential area, therefore the subscribers who wander there can have higherquality communication links and cellular network can provide a large coverage. However, asmultiple base stations are introduced into conventional network, different types of basestations would have greater interference to subscribers, which leads to more various andmore serious interference in the whole system. In particular, when Femtocells equipped withclosed subscriber group character, the subscribers without access authority will be interferedseverely. Thus novel interference coordination technology is required to reconfigure theradio resource in LTE wireless network systems.In this article, we first introduce a variety of base stations in heterogeneous networkfrom the network structure’s perspective. A study of interference scenarios consideringFemtocells has been given detailed. The downlink OFDMA resource managementtechnology in LTE systems comprises three major parts: interference graph construction,user grouping and channel assignment. The method that using the graph based networkmodel to coordinate the interference is verified in this article. We also simulate and analyzetwo algorithms used for graph construction. Simulation results show that the weightdistribution method based on interference types can represent the system interferencescenario more effectively.A novel interference coordination method based on simulated annealing algorithm foruser grouping is proposed in this article. The difference between this novel method and anexisting method is compared and analyzed by simulation. As it is shown in the simulationresults, the proposed approach can mitigate the interference effectively as it can allocate thewireless channel rationally. As a result, the receive SINR of both Femtocell users and Macrocell users are improved effectively. When the system is under normal load, ourproposed method could also save11.4percent of channel resource and enhance the spectralefficiency.