This thesis deals with analysis and modelling of power line communications. The main aim is to examine the effects influencing transsmision of communication signals on powerline networks and theoretical capacity of the PLC channel using PLC framework created in NS-3. The introduction summarizes the theoretical knowledge in the area of data transmission over power line distribution network. Different types of noise and possibilities of calculation of theoretical transmission capacity are described as well. Several simple simulations are realized in practical part of this paper. These simulations explore the influence of the distance between the transmitter and receiver, length, impedance and number of branches between these nodes, affect of ...