New Applications Using PLCs in Access Networks

Abstract

Access Networks in telecommunications, such as digital subscriber lines (DSL) and wireless broadband networks (WBN) have become so popular that these systems are now found in almost all regions. The widespread use of these systems has brought about the need for research into new ways of resolving, or at the very least, minimizing the impact of problems that affect the performance of these systems. In terms of DSL systems, crosstalk is one of the main performance limiting factors, principally when operating at high frequencies, as is the case with VDSL (very-high-bit-rate DSL) networks. Consequently, the required high data rates of VDSL systems may not be achievable if crosstalk levels are excessive. Across WBN systems, the existence of co-channel interference increases the system's noise levels and also degrades the network's overall performance. It may be impossible therefore, depending on the noise level, to get even minimum system access. It is therefore necessary to plan a way of controlling these noise levels across both access networks. Programmable logic controllers (PLCs) are the main types of controllers used within the industry. One of their characteristics is the fact that they can operate within aggressive environments (for example, at high temperatures or within high humidity levels) as well as having high operational speeds in comparison with corresponding electro-mechanic control systems; the PLC becoming a highly efficient control device with multiple usage possibilities. Hence, the use of PLCs across access networks opens up additional fields of application for this type of device, especially due to the fact that up until now, the PLC’s widest form of use has been in the industrial sector. Additionally, the robustness, flexibility and speed of the PLC allows it to be used across access networks without any additional need for major configuration changes to already installed equipment, i.e.; the implementation of a PLC into a system does not generate excessive costs or require excessively specialized configurations. PLC application will focus on automated configurations in order to reduce system noise on access networks (DSL and WBN) with the intention of making sure the performance levels of these systems are not degraded in any way and are also able to operate within the expected performance parameters. In this chapter, we propose alternative PLC applications on two types of broadband networks. Basic concepts about DSL networks and wireless broadband networks are presented in section 2. In section 3 the application of PLC on broadband networks is discussed. Final comments are presented in section 4.