Coded 64-CAP ADSL in an impulse-noise environment-simulation results

This paper describes performance results of E1-ADSL (2.048 Mb/s asymmetrical digital subscriber line) transmission based on carrierless amplitude/phase modulation (CAP) in an impulse-noise environment. Various coding schemes for error protection are investigated. Code options are Reed Solomon code with interleaving, array code and trellis coding, or interleaved trellis coding. The simulation results are based on real measured impulses from an impulse-noise measurement campaign carried out by German Telekom. The inter-arrival times between impulses were either assumed to be constant (worst-case scenario) or were delivered from a distinctive stochastic generator with an inter-arrival time density according to a model also derived in the German campaign. It was found that the RS codes, even with a quite small error-correcting capability, achieved acceptable error performance. Array codes can also be a low-complexity alternative. Trellis coding alone, as expected, was not very effective against the impulse noise.