A Home Traffic Cop

Tue, 04/30/1996 - 8:00pm
Clifford R. Holliday, P.E.

Around the world, deregulation of the telecommunications industry is resulting in competition among telephone carriers, cable TV services, utilities and other newcomers. One effect of this competition is the sudden emergence of not one, but several actual and potential broadband communications networks into homes and small businesses. This was spurred initially by the goal of interactive video services. In the last year, however, it has been shown that interactive video will not, by itself, pay for the infrastructure investment. Other services must be provided over these broadband residential access networks in order to justify the investment. These services include high bandwidth access to the Internet and to private networks, voice telephony, electronic games, home automation, home security, utility monitoring and utility control, and many other, as yet unimagined applications.

For the last several months, a group of individuals from a variety of firms involved in the development of the network of the future has initiated a new concept that is a basic enabler for that network. This concept is so important to the realization of a multiple provider, competitive, residential environment, that it is necessary. Otherwise, that envisioned future will have no realistic chance of occurring. This concept has been dubbed the "Residential Gateway." It is similar, in part, to other work that is going on in various standards bodies, such as DAVIC, ATM Forum, EIA, VESA and IEEE 802.14. The Residential Gateway is not meant to compete with, but integrate into, these implementation groups. However, the Residential Gateway concept uncompromisingly takes the position of the consumer in viewing and ultimately interacting with network services. Also, this approach is dedicated exclusively to residential requirements, rather than compromising those needs with business and institutional related concerns.

Residential gateway concept

To understand what the Residential Gateway concept is all about, let's step back and consider what is (broadly speaking) proposed for the near future. Several different networks to the home are planned. These will include the existing twisted pair, telephone network, and the coax (and fiber), cable TV networks. In addition, there will be (not all necessarily at the same place and same time-although that coincidence is not precluded) DBS networks, hybrid fiber/coax networks, fiber-to-the-home networks, ADSL networks, ATM networks, switched digital video networks, PCS networks and probably others. Not only are these competing networks, they are incompatible at various levels of the OSI model (i.e., they are incompatible in more than their basic physical interface characteristics).


This incompatibility and the competition (among the networks in functions, price, availability, and in other areas) mean that ultimately residential customers will be faced with the prospect of dealing with a very complicated multi-node switching problem. These same customers have trouble programming a VCR (surveys indicate that up to 70 percent of the adults, in fact, can't program a VCR). It is inconceivable that they will be able to deal with this problem. If they cannot, there are only two options; either give up the stated model of the future (which is unrealistic because it is already beginning to be put in place), or devise a technology solution that will handle this function and hide the complexity from the consumer. The Residential Gateway is an answer to this dilemma. It inserts a control function between external networks and in-home networks and devices. The Residential Gateway serves a "traffic cop" function-controlling and routing traffic so as to allow maximum use of all facilities. See Figure 1 for a depiction of the Residential Gateway serving as a traffic cop for the home.

The idea of the Residential Gateway, then, is to hide all of this complexity from the consumer and perform the needed functions in the background, similar in concept to the devices now available to automatically program VCRs. The Residential Gateway provides an intelligent device capable of terminating all of the proposed networks bound for the home. It also is capable of terminating all of the in-home networks (twisted pair, coax, X-10, security, HVAC, data/LAN, audio, video, etc.), and provides for seamless (and painless) interconnections between inside and outside networks as well as providing a user-friendly control interface. Ultimately it allows the customer to operate his in-home devices over the network(s) of his choice, at the highest level of functionality, and without concern as to the switching and interface complexities involved.

The Residential Gateway achieves this by an adaptation of the classical PC design. A bus connects network interface units (NIUs) and customer premise interfaces (CPIs). NIUs are installed on a one-for-one basis to match the desired incoming networks. Thus, there are ATM, DBS, telephony, cable TV, etc. NIUs. The CPIs, likewise, are provided to match the devices providing the services desired in the home. Thus, there will be television, VCR, telephone, computer, etc. CPIs. See Figure 2 for a depiction of this arrangement.

All material is converted to digital to cross the Residential Gateway bus. On the home side the material is converted back to analog if necessary. Eventually all material coming into the Residential Gateway will be digital and will require no A/D conversion. The Residential Gateway therefore is thought of as a bridge device that will allow for a graceful move from today's networks and devices to tomorrow's.

In today's world, the Residential Gateway is possibly an overkill (although some of the desirable multiple device capabilities would be difficult and expensive to achieve in currently available ways). However, in the evolving world of multiple networks (with multiple protocols) providing source material for these home devices, the Residential Gateway will be a necessity, not a convenience. It will hide the complexity of the multiple sources to multiple (and incompatible) sinks problem.

Other benefits

While the Residential Gateway concept is primarily aimed at filling needs for the consumer, it also meets the needs of network operators and device (consumer electronics) designers. The main concern for these latter two groups is in having a standardized interface point for their operations and for their design efforts. The Residential Gateway will greatly simplify the problem of network and CPE (customer premise equipment) device designers by the standardization of interfaces, while still leaving the opportunity for functional innovation for competitive differentiation.


The development of new services will no longer require that network and CPE developments take place at the same pace. New and innovative end customer services will be achieved by the design of new CPE, and where necessary, by the design of new CPIs (customer premise interfaces-the cards in the Residential Gateway looking toward the home). The addition of MPEG/ADSL, ATM, or other networks will be accommodated by simply adding a network card of the appropriate type. With the approach outlined, the full capability of those networks will be available to a wide variety of home devices with full flexibility.

As noted above, the Residential Gateway concept will provide advantages to customers, network operators and designers. The following is a listing of the more important advantages this concept will provide to each of these groups.

Customers would gain both equipment and service advantages, including:

  • Reduces set-top requirements. Most American households have more than three TV's. The RG approach is more cost-effective than an expensive TV set-top box, and provides for the future requirements of interactivity. The trend among television and PC manufacturers is to move the digital decompression (MPEG) technology into the device. The RG represents an opportunity to centralize-and cost reduce-the network interface.
  • Makes changes (network or services) easy. The RG plug-and-play approach provides the consumer the ease of use he demands.
  • Hides complexity and facilitates multiple networks. The average home user has a great deal of trouble dealing with currently available home electronics. The introduction of multiple, competing networks providing various services will exponentially raise the complexity level. Without a simplifying approach, this envisioned future will be a disaster.
  • Added service options. If an approach that is truly user-friendly can be developed, then many more average consumers will be able to take advantage of the vast options that can be made available on these future networks.

Network providers would also benefit from the migratable nature of the Residential Gateway concept in the following ways:

  • Meets analog and digital needs. A single, flexible, extensible intelligent interface is ideal to satisfy both short term "analog" needs, along with high bandwidth "digital" services, such as Internet access, HDTV and services yet to come. The RG approach provides this intelligent interface and has many inherent advantages.
  • Standardizes home interfaces. There is a need for standardization of customer premise equipment (CPE) which allows the service provider to flexibly offer new digital application services. The RG approach provides a common core set of protocols in a one box design.
  • Works with existing business models. Service providers easily can extend their current business model for the RG approach, and offer emerging technologies and services, such as access to the Internet.
  • Enhances servicing activities. One service provider can perform all security and network diagnostics from the external network interface. The RG will be easier to service and maintain than currently proposed TV set-top approaches.
  • Improves remote diagnostic capabilities. The RG approach enables remote software diagnostics and extensive network monitoring to be performed, resulting in substantial labor savings in field service calls.

For designers, the RG approach offers the following:

  • Defines network interfaces. Currently, device designers generally know the type of network to which a given home device will be connected. For example, a VCR is going to be connected to a network that will provide NTSC signals (or line level video), even if it comes from a variety of physical sources. In the future, this VCR may need to be connected to an ADSL channel carrying some (MPEG-1, MPEG-2, etc.) compressed signal. The Residential Gateway will provide a standard interconnection for the VCR and will thus eliminate this problem.
  • Defines home device interfaces. Network designers have the same problem. What will the home devices that will be on the business end of their networks look like? Without a standardized design, they must guess or provide multiple interfaces.
  • De-couples network and end device development. Development of network technologies and home device and applications technologies are driven by different forces and are on very different timelines. The Residential Gateway concept will de-couple advances in one area or the other, thus reducing false obsolescence and increasing advancement opportunities.

In summary, deregulation and the telecommunications bill being re-written will have a dramatic impact on the U.S. consumer. On the one hand, consumers will see the benefits of technology developments quickly integrated into consumer products. On the other hand, consumers will have to pay for previously subsidized services, and bear the full costs of bringing this new technology into the home. This influx of rapidly advancing technology will bring great complexity to the home as well as unanticipated costs.

The consumer must be brought to the prime focus of any future network plans. To do so, a standardized interface must be developed for the home. This interface must simplify the control and operations to the consumer, while simultaneously allowing him to take advantage of the vastly expanding capabilities of the competing networks. It also must simplify the network operators' and the designers' jobs. The Residential Gateway, as proposed, will achieve these goals, while offering the opportunity to all concerned players to competitively pursue their business plans.

Author Information
About the author
Clifford R. Holliday, P.E. is the owner of B& C Consulting Services. His background includes 30 years spent at GTE, where he was in charge of long-range network architecture. Holliday can be reached via e-mail at



Share This Story

You may login with either your assigned username or your e-mail address.
The password field is case sensitive.