**7. References**

Arora, J. S. (2004). *Introduction to Optimum Design.* – 2nd ed. – Elsevier


**0**

**13**

**Over Copper**

<sup>1</sup>*Federal University of Pará*

<sup>2</sup>*Ericsson AB* <sup>1</sup>*Brazil* <sup>2</sup>*Sweden*

**Measurement and Modeling Techniques**

Diogo Acatauassu1, Igor Almeida1, Francisco Muller1, Aldebaro Klautau1,

Digital subscriber lines (DSL), the broadband data transmission technologies that use the copper cable as channel, are the most used Internet media around the world with more than 300 million users (Oksman et al., 2010), Much of the DSL success is related to the cost-benefit for both operators and served consumers. As the transmission channel is the common copper twisted-pair telephone cable, there is no need for large investments in infrastructure, because

Over the years, DSL systems suffered a step-by-step evolution, being divided in different generations according to the increase of its data rates and technology improvements (Odling et al., 2009). A lot of elements were evolved in this process. Two of them can be highlighted. The first one was the development of modern signal processing techniques to avoid crosstalk effects in DSL transmissions, such as the so-called dynamic spectrum management (DSM) techniques (Cendrillon & Moonen, 2005; Moraes et al., 2010; Oksman et al., 2010; Song et al., 2002). The second one was the reduction of the used copper cable length, resulting in a consequent reduction in the attenuation imposed on the transmission signals. This fact allowed the increase of the used bandwidths, and consequently

The standards of the first and the second generations DSL, matching the integrated services digital network (ISDN) (ITU-T, 1991) and asymmetric DSL (ADSL) family (ITU-T, 1999a; 2003; 2005a), were developed to operate over several kilometers copper cables achieving maximum data rates up to 20 Mb/s. The standards of the third generation DSL, matching the very high speed DSL (VDSL) family (ITU-T, 2005b; 2006), were developed to operate over hundred meters copper cables, achieving maximum data rates up to 100 Mb/s. This case, when users do not live near to the service provider's central office, fiber to street cabinets (FTTC) are

inevitable to make the copper loop sufficiently short (van den Brink, 2010).

the telephone network is largely consolidated and active in almost all the world.

**1. Introduction**

the data rates.

**for the Fourth Generation Broadband**

Chenguang Lu2, Klas Ericson2 and Boris Dortschy<sup>2</sup>

