Advanced emulation of channel transfer functions for performance evaluation of powerline modems

Typical powerline networks feature frequency-selective attenuation which has a relatively high dynamic range and sometimes large notches. This fact is usually idealized with flat in-band attenuation during the performance evaluation of PLC modems. Thus the noise margin under these channel conditions cannot be measured. Inserting L-C-R resonance circuits between devices under test (DUT) can introduce some kind of frequency-dependent attenuation of the transmit signal, However this method suffers from low flexibility, low accuracy and high complexity. This paper proposes a channel emulator-based platform for the performance test of powerline communications (PLC) modems in frequency range up to 500 kHz. It is capable of emulating the frequency-dependent channel characteristics accurately and conveniently. The result of margin tests shows that different techniques as well as different implementations of the same technique have different performance with the same channel; single-carrier modulations have higher margins as multi-carrier and spread spectrum modulations. All these facts can only be revealed by employing realistic channel conditions, therefore the flat attenuation is insufficient for a comprehensive and persuasive performance evaluation.