Page 97
12
NII Road Map: Residential Broadband
The Cross-Industry Working Team (XIWT) is in the process of examining how today's national information infrastructure (NII) can evolve into the future NII envisioned in the XIWT white paper, "An Architectural Framework for the National Information Infrastructure." This paper presents the methodology the XIWT is employing in this effort and some of the results obtained in residential broadband. In this context residential broadband refers to communications-based services using large amounts of access bandwidth to provide NII services to residential users.
Methodology
To understand NII evolution, it is instructive to examine the various overlapping and interdependent technology and business segments making up the NII. Examples of these segments include residential broadband, satellite-based communications, intelligent transportation system, personal communications services, enterprise networking, home automation, public telephony, electronic commerce, and the Internet. Each of these segments will undergo important evolutionary changes during the next decade. By piecing together the evolutionary directions of these segments, a vision of the overall NII evolution will emerge.
The initial portion of this study has not been to determine how the NII should evolve, but rather to understand the current technical and business directions of the various NII segments. No a priori assumption was made that these segments would evolve in a consistent fashion or that the result would meet the Clinton administration's or industry's vision for the NII. Indeed, although certain segments of the NII are overlapping and interdependent, others are evolving with apparently little interaction. One of the goals of this study is to identify where inconsistencies exist between the evolutionary directions of the NII segments and to identify the degree to which the combined segments miss the vision put forward for the future NII. Based on the results of this study, specific recommendations will be developed for reshaping evolutionary directions toward the target vision.
To understand how these segments are likely to evolve, industry experts from the relevant segments of the NII were invited to a series of NII evolution workshop meetings of the XIWT. These industry experts were asked to address three questions: (1) How would you characterize today's NII with regard to this industry segment? (2) What changes do you forecast for this industry segment over the next 3 years? and (3) What changes do you forecast will occur over the next 6 years?
The 3- and 6-year time horizons were found to be convenient milestones. Most industry planners have well-articulated views of how their industry will change during the next 3 years based on existing exploratory efforts and announced business plans. Changes likely to occur in 6 years are harder to predict; still, this is within the planning horizon of most companies.
These industry experts were asked to present their most likely scenarios—the one they would bet on occurring, not a fanciful view of what could be possible given dedicated industry and government efforts. These forecasts are predicated on whatever regulatory and policy changes these industry experts believe will probably occur during this planning period.
Page 98
Residential Broadband Evolution
Many services envisioned for the NII will demand significant amounts of communications bandwidth. To extend these services to the general public, broadband access networks to private residences and apartments will play a critical role in the NII. Residential broadband (RBB) networks are already widely deployed for entertainment video distribution services. Future residential broadband networks will provide increased bandwidth and two-way interactive capabilities supporting a wide variety of applications.
To characterize today's RBB networks and to understand how they are evolving to provide the capabilities needed in the future NII, the XIWT invited industry experts representing CATV companies, local exchange carriers, RBB equipment manufacturers, and satellite communications service providers to discuss current and future RBB networks.
The following is a summary of the views of these industry experts. It does not necessarily represent the views or positions of the XIWT or its member companies.
Residential Broadband Today
Access Architecture
Today's residential broadband (RBB) is composed of over-the-air broadcast networks, CATV networks, microwave access networks, and direct reception from home satellite antennas. With the exception of emerging satellite-based delivery systems, today's RBB access networks are based on 6-Mhz analog channels. In a recent study of CATV networks conducted by CableLabs, typical downstream capacities were as follows:
|
Although the amplifier housings employed in current CATV networks are designed to accommodate a return path amplifier (i.e., they are two-way ready), most of today's CATV systems have unactivated return channels. Roughly 20 percent of today's CATV systems use some fiber-optic links to bypass long amplifier chains in the trunk portion of the network. Currently a mix of 300-, 400-, 450-, and 550-MHz amplifiers is used. Service is typically provided to residences and apartments, with relatively few business locations connected to CATV networks. There is usually only a single CATV operator in a given service area, with nascent competition from microwave and direct broadcast satellite service providers. TVRO (television receive only) background antennas that are 1 to 2 meters in diameter are used by a small fraction of residential customers.
Services available over today's RBB networks typically consist of the following core set:
|
In addition, the following emerging services have been deployed on a limited basis:
|
Page 99
Residential Broadband: 3-Year View of Access Architecture
Three years from now most CATV networks are expected to be 750-MHz systems providing 77 analog channels in the 54- to 550-MHz band and hundreds of digital channels in the 550- to 750-MHz band. Most CATV networks in that time frame will have fully activated return paths using the 5- to 40-MHz band. These systems will have a maximum chain of four to five amplifiers providing improved quality and reliability. There will be a clustering of cable systems in many metropolitan areas to provide connectivity to business and residential customers throughout these metropolitan areas.
Local exchange carriers will provide video dial tone (VDT) service in many metropolitan areas using either hybrid fiber-coax access or fiber-to-the-curb architectures. These VDT networks will include a level-1 gateway for selecting the video information programmer. The video information programmer will provide a level-2 gateway for selection of the specific video channel. Most VDT networks will include three to five level-2 providers, including the LEC itself.
High-power direct broadcast satellites allowing reception from small antennas (those less than two feet in diameter) will be widely available for supporting video and data services to residences. Terrestrial radio frequency access networks using cellular principles in the 30- to 40-GHz band will be deployed in a number of areas.
By 1998, many of today's emerging RBB services will be considered core services of most RBB networks. The following core RBB services are expected to be available:
|
In addition, the following emerging services are expected to be deployed on a limited basis in 1998:
|
Residential Broadband: 6-Year View of Architecture
From 1998 to 2001, fiber will migrate closer to residences, allowing available bandwidth to be shared among fewer customers and providing increased upstream bandwidth.
Despite current experimental deployments of 1-GHz cable systems, CATV networks in 2001 are expected to be predominantly composed of 750-MHz fiber serving area systems. Fiber node sizes will be reduced to 125 to 250 homes, with a maximum of 1 or 2 amplifier cascades with a move toward entirely passive networks. To provide additional upstream capacity, the analog portion of the spectrum could be reduced to 88 to 400 MHz and
Page 100
the return path expanded to 5 to 70 MHz. Satellites with onboard ATM switching will be deployed supporting two-way bandwidth on demand.
By 2001, the following are expected to be core services of RBB networks:
|
Summary
This paper presents the methodology being used by the XIWT in its NII evolution study and summarizes information collected on RBB evolution. The XIWT continues to collect information on industry evolution plans in other NII segments. This information will be included in a forthcoming white paper on NII evolution.
