ATM over ADSL Probe in Telecom Italia Environment Stanislav Milanovic, Serco Group plc Alessandro Maglianella, Telecom Italia

Introduction ADSL gets its name from the asymmetry of how data is sent and received, providing different rates in the upstream and downstream directions. This send/receive rate asymmetry is effective for many typical applications where more data downloads than uploads. Business can use ATM/ADSL for all of their communications needs (Internet access, voice services, data services among sites and video services) with guarantees for quality of service.

The Local Loop Constraints Figure 1. Typical Copper Feeder/Distribution Loop

ADSL Modem Figure 2. ADSL uses FDM and echo cancellation to divide the available bandwidth for services

Objective The goal of proposed access network configuration is to evaluate network performance of two integrated technologies — ATM and ADSL — for broadband multimedia and Internet services distribution.

Requirements Telecom Italia have addressed the following functional requirements in order to enable a mass market for ADSL: Easy Migration from existing ISP Access Infrastructure, Simultaneous Connectivity: Internet and Corporate network, Security, Multicast, Multiple Service Class Support, Quality of Service Support.

ATM/ADSL Networking Figure 3. End-to-end ADSL-based Broadband Network Architecture

Test Bed Figure 4. Test Bed Layout

Measurements Performed measurements were focused on a maximum length determination of the phone cable, with no cell loss during transmission, while varying a phone wire diameter under a constant downstream of 7.1Mb/s and under a constant upstream of Mb/s in presence of various noise signals.

Results Figure 5. Noise impact on signal propagation over phone cable

Conclusion Results of testing demonstrate that ATM/ADSL is able to send data/voice/video services under a high rate downstream/upstream within a range of nearly 4.5Km over ordinary subscriber loops without any cell loss. For the future, it is likely that combinations of fibre feeding access nodes and VDSL feeding premises over copper (so called Fibre to the Neighbourhood, or FTTN) will be the next generation network topology for telephone companies in most countries of the world.