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.