INVESTIGATION OF INTERFERENCE IN THE HETEROGENEOUS NETWORKS OF THE LTE-A STANDARD
The aim of this paper is to investigate interference in heterogeneous networks of the LTE standard using the example of the Macro-Picot scenario, depending on the location of subscribers within the Macro-Picot coverage area. In heterogeneous LTE-A networks, pico-BSs are deployed to adequately discharge traffic from the macro-level and to reduce the distance between the base station and the mobile station. However, the macro-BS causes strong interference to the pico-MS due to its higher transmit power. Therefore, inter-cell interference is the biggest problem in LTE-A. To study the interference in heterogeneous networks, both the material of Russian scientists and foreign articles were analyzed. First, the location of the pico-MS within the Macro network is selected. Because the closer the pico-MS to the pico-BS, the less interference there is. Therefore, pico-MSs are located on the border of the pico-BS service area to investigate interference in a heterogeneous network. Further, for each BS, calculations are made for its model of path loss. For Makro-BS, the Okamura-Hata model is applied. A special model is applied to the pico-BS, which takes into account losses during repeated passage of the signal through the floor, from the walls, which allows to provide such characteristics as frequency reuse at different floors of the building, remote power loss factor. After, a general formula is derived for calculating the signal-to-noise ratio and interference. Based on the calculations for various parameters of the BS, graphs are given for identifying the optimal case when the interference is minimal. In situations where the size of the picocell increases and when the picocell approaches the macrocell, more pico-MS is located at the edge of the picocell. For each pico-MS, the distance between its location and the location of the pico-BS is calculated, as well as the distance between the pico-MS position and the location of the macro-BS. Then, two distances are used to calculate the level of the signal received from the desired source (pico-BS), and the interference level obtained from the macro-BS. In addition, pico-MS is distributed according to their SINR from top to bottom. In conclusion, recommendations for improving the interference pattern in the Macro-Picot scenario are presented, and some of the main aspects of heterogeneous network technology are displayed, and outputs from the unfavorable scenarios of the heterogeneous network sweep are made and recommendations for optimizing heterogeneous planning are given.