Comparison of precoding schemes for digital subscriber lines

|Precoding at the transmitter side is a practicable method for transmission over intersymbol interference channels. In contrast to decision{feedback equalization no error propagation occurs and coded modulation can be applied as for the intersymbol interference free channel. In this paper, Tomlinson{Harashima precoding and exible precoding are analyzed and compared. The dualities and di erences are discussed. The focus of interest is the application of precoding to fast digital transmission over twisted pair lines, such as high{rate or asymmetric digital subscriber lines. It turns out that exibility | which is not necessary in the speci c application, digital subscriber lines | of exible precoding is paid with a performance loss compared to Tomlinson{Harashima precoding. Keywords| Precoding, High{Rate Digital Subscriber Li-