Recent progress in home networks enhances the application of broadband power line communication (BPL) since it does not require any installation of new communication lines or outlets. However,high-density distribution of BPL devices may bring down the access quality. Besides,the electromagnetic field radiating from the power line may cause interference with other radio systems. Thus,the objective of this study is to investigate the impact of cumulative interference in BPL systems,especially focused on indoor environment. A 2-D model describing the BPL transmission activity is proposed. Based on transmission characteristics of the main networks,it takes into account the coexistence effect of the BPL devices. The maximum acceptable density of BPL devices and the radiation field are finally determined. Recent progress in home networks enhances the application of broadband power line communication (BPL) since it does not require any installation of new communication lines or outlets. However, high-density distribution of BPL devices may bring down the access quality. Thus, the objective of this study is to investigate the impact of cumulative interference in BPL systems, especially focused on indoor environment. A 2-D model describing the BPL transmission activity is proposed. Based on transmission characteristics of the main networks, it takes into account the coexistence effect of the BPL devices. The maximum acceptable density of BPL devices and the radiation fields are finally determined.