Research On The Femtocell Interference Coordination Algorithm In LTE System

With the continuous improvement requirements of wireless rate and the continuous development of wireless mobile data services, LTE commercial is necessary and imperative. The band LTE used is relatively high which reaches 2.3GHz or 2.6GHz, this high-frequency electromagnetic waves will be under a lot of penetration loss when penetrating buildings, resulting in a significant decline in signal quality. However studies show that:in the macrocell, 2/3 of voice and over 70% of data services occur in the chamber. Therefore, in order to solve the indoor coverage issue, the home base station (femtocell) concept is introduced. Femtocell introduced to the traditional cellular systems poses serious interference problems, and due to the plug and play features of femtocell, its deployment can not be planned and optimized. Interference coordination requires new strategies.This article describes the technical advantages and challenges of femtocell, a detailed analysis of the interference caused by the introduction of femtocell, on the basis of studing on traditional inter-cell interference coordination strategy and existing interference coordination femtocell technology, for femtocell serious co-layer interference, we improved the Femtocell interference coordination algorithm based on Femtocell group. We first establish a Femtocell interfering matrix according to the interfering neighbor table, and then according to the Femtocell interference matrix, devide femtocells into groups. After grouping, the frequency band can be reused between different groups. On the basis of the orthogonal frequency allocation between the femtocells in the same group, we dynamically allocate femtocells thequency resources with full consideration of the differences of channel and traffinc of femtocell. For the low utilization of spectrum resources of the first algorithm, we improved the spectrum sensing coordination interference algorithm, on the basis of first algorith, spectrum sensing technology is used to detect macrocell band unoccupied by macrocell users, according to the order of magnitude of interference and traffic, femtocell carry the idle frequency resources. Spectral efficiency is further improved without the mutual interference between femtocell and macrocell users.Through the simulation of the proposed two algorithms, we analyze the impact of interference threshold wihich has impact on the size of the group size of femtocells and at different frequency resource allocation in the first algorithm, under the appropriate interference threshold, the first algorithm can effectively realize frequency resource reuse between different groups of femtocells, meanwhile co-channel interference between femtocells is effectively solved and the system capacity and spectral efficiency are improved. The second algorithms further improve the bandwidth utilization of femtocells based on the protection of the macrocell user QoS. The two algorithms are instructive to the follow-up studies of Interference Coordination Technology and femtocell deployment.