Radu Suciu

Simplified power allocation and TX/RX structure for MIMO-DSL

We investigate power allocation and crosstalk cancellation for MIMO-DSL (a.k.a. bonded-DSL) systems. Exploiting a property of the DSL channel, namely column-wise diagonal dominance, allows us to simplify the power allocation and crosstalk cancellation problems. This leads to a significant reduction in initialisation and run-time complexity whilst maintaining near-optimal performance. We. develop a bound which relates the deviation of the simplified power allocation to the degree of column-wise diagonal dominance. Reliable transmission at near-capacity data-rates is also demonstrated through simulation.

Simplified power allocation for the DSL multiaccess channel through column-wise diagonal dominance

In the newest generation of DSL systems crosstalk is the dominant source of performance degradation. Many crosstalk cancellation schemes have been proposed. These schemes typically employ some form of coordination between modems and lead to large performance gains. The use of crosstalk cancellation means that power allocation should be viewed as a multiuser problem. In this paper we investigate optimal (i.e. capacity maximizing) power allocation in DSL systems which employ coordination to facilitate crosstalk cancellation. By exploiting certain properties of the DSL channel it is shown that power allocation can be simplified considerably. The result has each user waterfilling against the background noise only, explicitly ignoring the interference from other users. We show this to be near-optimal for upstream DSL when central office (CO) modems are coordinated. Compared with conventional waterfilling which is done against the background noise and interference, the performance gains are significant.