Broadband is proliferating at a torrid pace, with thousands of subscribers added every month. Worldwide subscribers are expected to surpass 175 million by the end of 2005. Fueling this explosive growth are the digital subscriber line (DSL), cable, and passive optical network (PON) access technologies. DSL dominates this field by far, touting over 120 million subscribers. After years of hype, PON is finally beginning to gain market penetration too.
Why are telcos so intent on deploying these technologies? Why is there such a sense of urgency? It's a matter of survival. With collapsing plain-old telephone revenues and stiff competition from cable operators for data services, telcos believe triple-play converged services and Internet Protocol television (IPTV) will offset the losses. And not only must telcos offer video services to compete, they also must differentiate their services by providing exceptional quality of experience (QoE) to the end-user.
The QoE needs to permit fast channel changes, multiple streams of high-definition images, ease of use, and personalized and interactive programming guides. Additional QoE features such as the ability to pause, fast forward, and replay video on demand will transform the traditional broadcast TV into a ?virtual unicast? TV, allowing telcos to generate higher average revenue per user (ARPU).
PON technology?with its APON, BPON, EPON, GPON, and GEPON variants?and VDSL2, the newest of the DSL technologies, can deliver ample bandwidths necessary for good QoE. The key question is how each of these technologies can be used in the most economical way for delivering 20- to 30-Mbit/s bandwidth to the end-user.
To provide this bandwidth, which is necessary for good QoE, fiber must be brought closer to the user. One approach is to pull the fiber all the way to the user (FTTU) and use PON to connect to the end user. This option perfectly suits green fields where no copper infrastructures exist. It's also attractive for competitive local-exchange carriers (CLECs) who don't have to depend on incumbent local-exchange carriers (ILECs) to lease the last-mile access.
However, financially strapped ILECs aren't prepared to invest in costly last-mile fiber, expensive right-of-way to each home, and the infrastructure work needed to deploy new fiber on every street, which could add up to billions of dollars of capital expenditure (CAPEX). Countries like Japan, Korea, and Taiwan offer government-sponsored initiatives to bring fiber to the user. Yet ILECs throughout the world who own established copper infrastructures (brown fields) in the last mile would use it to optimize the CAPEX. This means deploying hybrid access networks based on VDSL2 over copper in the last mile.
So the race is on to deliver QoE to the end user. VDSL2 and PON, two leading conduits, are ready to help make it a reality.See associated figure