Comparison performance of DMT in ADSL systems in different noisy channels

Today, Internet access over a digital subscriber line (DSL) has been extended over the world. Recent technological advances have increased the potential capacity of the telephone operators’ access networks, which were originally intended only to provide a PTSN. However, due to an imperfect balance between the twisted pair channels, different noises occur on the telephone lines. In this paper we apply different 16-QAM constellations (rectangular form and two non-rectangular form) to ADSL system with burst and normal noisy channel. The results of simulation show that rectangular constellations have better performance (especially BER) with respect to non- rectangular constellation in both normal and burst noisy channels.