Coexistence analysis of asynchronous digital subscriber lines with different sampling rate and carrier frequency spacing

G.fast is the next-generation digital subscriber line (DSL) technology targeting bit-rates of up to 1 Gbps. Very high speed digital subscriber line 2 (VDSL2) is the the latest DSL technology delivering bit-rates of up to 100 Mbps. Replacement of VDSL2 by G.fast modems will be gradual, which implies coexistence of these two systems. G.fast and VDSL2 use different symbol durations, carrier frequency spacings, and sampling rates, which results in inter-carrier and inter-symbol interference (ICSI). We derive an analytical model of ICSI capturing these differences in modulation. Furthermore, through simulations we show that for particular network topologies coexistence of the two systems results in significant bit-rate losses compared to an interference-free scenario.