Gateways To The Future

There's a similar kind of evolution going on in terms of the residential gateway. Many in the design industry agree this device will be an important piece of the puzzle that brings ubiquitous high-speed connectivity to that great untapped market, the home. But given the array of access options available to consumers - DSL, satellite, broadband wireless, even (gulp!) dial-up added to several data-distribution options within the home, and you've got a melange of utter confusion.

Knowing that the residential gateway may prove to be the critical link in finally getting all the amazing communication technology we know and love into a true mass market, we at Communication Systems Design discussed the design of this device with several prominent OEM and component manufacturers. As expected, there is a wide range of opinions as to what should be included.

Some of the concerns ring familiar - a gateway device should be equipped to accommodate changing standards, and may be designed in such a way as to sit outside the home in a utilitarian sense, or as a piece of furniture, such as we've seen with PCs in the past few years. Will the gateway take the form of the set-top box, or will it be something we haven't experienced before? Part of the answer lies in visualizing what form tomorrows' home networks will assume.

Evolutionary, My Dear Watson
Ken Christy, product manager at Embedded Wireless Devices (Pleasanton, CA) says the industry will likely need to produce multiple gateway types for various functions, rather than a single device. "You'll probably be looking at one box with a DSL connection, for example, to handle data needs," he said. "Then for media, another one through the set-top box, and possibly a third one for home automation that works with the phone lines."

Amit Dhir, senior engineer of strategic applications at Xilinx Corporation (San Jose, CA), says networked multiple gateway-type devices will become the norm as the evolution of consumer electronics technology continues to blur the distinction between the home PC and other information appliances.

"People are likely to have disparate networks within the house," Dhir said, "There will be the PC network between desktop, laptops, scanners and other devices, which will likely use a PC as the gateway. Meanwhile, video/entertainment gateways will connect with appliances like digital TVs, MP3 players, gaming consoles, and the like."

Thus, Dhir predicts, the networked home will have multiple gateways initially but a single dedicated gateway that can provide high-speed Internet access while also networking disparate appliances and networking protocols. This unified gateway, he says, is the winning design for the home networking market. But it's also likely that the evolution of gateways will lead to an entirely new device that takes the best elements of gaming consoles, PCs, utility-centric gateways (for meter reading and energy optimization, for example), and other devices.

Take, for example, a settop box. As Dhir points out, set-top boxes are basically a simple device that decode audio and video signals to output to either an analog or digital display, while performing MPEG-2 audio and video compression. At the same time it has the capability for interactive TV, interactive gaming, digital video recording (DVR), and video-on-demand via a smart card reader.

However, according to Dhir, in the future this device will likely be enhanced to support multiple broadband access technologies (xDSL, satellite, cable, ISDN, and so forth) and home networking technologies (phone/power lines, HomeRF, Bluetooth, IEEE 802.11b, Ethernet, 1394), evolving into a universal gateway.

Bernard Goffart, product line manager at Alcatel Microelectronics (Brussels, Belgium), also shares the integrated-device outlook in the long term. "An integrated access device (IAD) is a residential gateway providing several services such as voice (VoIP, VoDSL) or video services using the data pipe."

Market trends, says Goffart, are making it necessary to design a single gateway for different usages. "Today, different gateways connect with ISDN, ADSL, SHDSL, and Data Over Cable Service Interface Specification (DOCSIS)," he said, but merging such connections into a single box makes sense. "You might see a set-top box with DSL connectivity, like DirectTV DSL, for example," he noted, "or a gateway combining ADSL and SHDSL."

Modular, Simple Design
Peter Kempf, vice president of technology planning at Conexant Systems (Newport Beach, CA), says that designers should keep in mind that consumers ultimately want a modular, simple design that uses existing protocols (preferably those supported by Windows) to use in home networks. "Today's modular approach to home networking will give way to a more integrated solution, but in our view is this is likely 2 to 3 years before the feature set will settle down to create a true residential gateway."

Kempf says network processors are a critical component for designers to include, as engineers can easily support routing protocols for various distribution methods, such as Home Phoneline Networking Alliance (HomePNA), 802.11, and powerline.

"Residential gateways will take on multiple form factors, with different WANs supporting different combinations of multiple LANs," says Alex Vasilevsky, chief technology officer at Ucentric Systems in Maynard, MA. "They could be integrated into other devices, such as set-top boxes, or not. From Ucentric's point of view, gateway functionality is 'table stakes' - a necessary building block - for what we know to be the real market opportunity for networked homes."

That opportunity, Vasilevsky says, requires a design with the ability to remotely provision gateway functions for future entertainment and communications. As to whether we'll need separate or unified gateways, he also predicts an evolutionary path.

"There is an important temporal element here," he said. "Initially, there will likely be separate gateways for different purposes, as consumers adopt early lead applications and incorporate the networked Internet lifestyle more fully into their daily lives - starting with more entertainment-oriented services and evolving to the more control-oriented possibilities."

"Over time," he notes, "as networks evolve to all Internet protocol - where voice looks the same as video that looks the same as Internet data - we will transition to a single gateway."

It's what's inside that counts
Once data reaches the residential gateway (the central receptor), what happens from there? It must get out to individual points within the home. And there are those who say it is a good idea for wireless methods to handle this distribution once the data is in the house.

Several standards vie for prominence here. There are a few new homes being built with Ethernet (IEEE 802.3) cabling to almost every room, and this is nice as it allows 100-Mbps transmission speeds and ready adaptation to emerging standards, but it also requires cumbersome wiring to be installed if it doesn't already exist.

But, while some new homes are being Ethernet enabled, there are millions of homes in the world that are not. That's why much interest has been placed on using wireless transport as the networking technology of choice.

The big challenge for residential gateway designers, however, is choosing the right wireless technology. Designers are faced with a flurry of options on the wireless front. From HomeRF to Bluetooth to 802.11, developers of residential gateways have a tough choice to make when selecting a wireless option.

Right now, the early standard winner seems to be the IEEE 802.11a and b wireless LAN (WLAN) specifications. With more enterprises rolling out WLAN systems and network interface card (NIC) and access point charges on the decline, WLANs have emerged as a clear alternative for the home market.

Dhir said that 802.11 (Wireless Ethernet) has significant momentum. And one of the big reasons he points to is the development of the IEEE 802.11a specification.

This specification calls for WLAN systems to operate in the 5-GHz band and employ an orthogonal frequency division multiplexing (OFDM) modulation scheme. "This technology (used in 802.11a) uses an Ethernet-type media access control (MAC) layer based on carrier sense multiple access/collision avoidance (CSMA/CA) like 802.11b," Dhir

said. Much like wired Ethernet, he explained, the 802.11a products will be great for data traffic.

But, what about voice? According to Dhir, while 802.11 is well suited for data, it falls short on the voice front. That's why, as he points out, some are eyeing HiperLAN2 as a better alternative for establishing WLANs in the home.

Like 802.11a, OFDM also works in the 5-GHz band and employs an OFDM radio. But, unlike 802.11a, HiperLAN2 employs a TDMA-based MAC. This TDMA approach, Dhir said, allows "essential voice support."

In addition to HiperLAN2, some have pointed to HomeRF as a viable competitor to 802.11a/b in the home networking market. Another competitor to 802.11 could also arise in the form of Bluetooth.

As most know, Bluetooth has gotten the most hype. And while most of that hype has surrounded around connecting devices together, a good portion of industry members are already pondering the use of Bluetooth as a WLAN technology. But, an important question must be asked. Is Bluetooth really designed for WLAN operation?

As Dhir says, "Bluetooth is the ideal personal area network (PAN) and cable replacement solution. It will uniquely allow PANs to be created and torn down at a moments notice without an IT department."

But as a WLAN/home networking protocol, Bluetooth still has some way to go. In its current form, Bluetooth is not optimized for a WLAN set up. According to Dhir, Bluetooth is a good intra-device data communication tool. But, its frequency-hopping spread-spectrum (FHSS) modulation scheme and its lack of support for direct Internet access could hamper Bluetooth as a WLAN/ home networking technology.

A Dark Horse?
HomeRF could be considered a dark horse on the wireless side of the home networking market. Early on, the pundits viewed HomeRF as a viable solution for delivering connectivity to the home. Going for it, the spec had big backers, such as Proxim and Intel, and was designed specifically for the intricacies of the home.

But, HomeRF was plagued by problems. Speed became an ultimate headache for backers of the protocol. And as 802.11 WLAN technology began to grab hold, HomeRF backers began to bail, including its most visible backer, Intel.

Of course, HomeRF is still fighting. According to Christy, implementation of the Digital European Cordless Telephone (DECT) standards within the shared wireless application protocol (SWAP) specification has been a big plus for HomeRF. And, with the adoption of the HomeRF 2.0 specification, some of the speed problems have been addresses.

But, as Christy pointed out, while the spec is starting to shape up, HomeRF will still have trouble overcoming the momentum of 802.11.

Dhir agreed, "This is one of the oldest home networking technologies (after infrared), and does a great job in supporting both voice and data, as the protocol's use of separate schemes for voice and data provides high reliability for both." However, he added that designs based on this technology have of late seen a mass exodus of supporters, especially with the continuing price plunge of 802.11b solutions. And now, with the faster throughput of 802.11a systems around the corner, HomeRF might be in trouble.

"We do not view this as an either/or debate," Ucentric's Vasilevsky says of the wireless standards wars. "The point of debating the differing protocols is somewhat moot," he said, "as different environments and devices have connectivity requirements that are uniquely appropriate for them."

Wired - Still An Option?
Despite the promise of wired solutions like phone and powerline networking (wherein signals travel through existing home wiring to various rooms), it's hard to get around the wireless juggernaut.

Terry Riley of Texas Instruments' (TI's) DSL group predicts that 802.11 will likely win out for home networking, and that it holds significant advantage over other options.

"The advantage is that 802.11b has a history and installed base within the enterprise community and has built a strong market through installations in airports, hotels, cafes, schools, factories, and so forth," Riley said, noting that the technology translates well to a home setting. The disadvantages of the protocol, he said - security, price, and QoS issues - are all being resolved. "Security, as with most wireless systems, is an issue, and the industry is working hard to resolve this within IEEE," he said.

PowerLine, Riley said, lacks successful deployments, and few vendors offer solutions. "The location of power outlets affects the ability to be a true home networking technology worldwide," he said, "and older wiring may have difficulties handling the transmission." Additionally, Riley says, a quick power usage increase (such as the furnace or air conditioning usage) may negatively impact data rates.

Riley voices similar concerns for the HomePNA standard. "HomePNA is only being deployed in North America where the in-home phoneline network is ample enough to support a full home network," he said, "but in Europe and other regions around the world, there is only one phone jack per home and as with powerline, older homes in the US may also have problems handling the network."

Dedicated Cat5 cabling, he says, also has issues. "It's the least expensive home networking technology from a component aspect, but if your home isn't wired already, the labor and time it takes to install is much more intensive than other networks, and you still need to buy Ethernet adapters for your appliances, as you would with other home networking options."

Conexant's Kempf said, however, that the Powerline HomePlug specification, currently capable of 14-Mbps speeds, has the right combination of a ubiquitous network and built in QoS and security. "While it may be a little late and cost a little more initially," he predicted, "Moore's Law will quickly make this the technology of choice for the wired backbone in a home." (See "HomePlug Standard Brings Networking to the Home," December 2000 Communication Systems Design, www.csdmag.com).

HomePNA, Kempf said, is another story. "While it may be cheap, HomePNA suffers from the fundamental problem of too few RJ-11 jacks," he noted. "With an average of only 2.5 jacks per household in the US, it does not create much of a network."

Xilinx's Dhir offers a holistic outlook. "While HomePNA seems an ideal technology in the US, it is impossible to network a house in Europe or the Asia/Pacific region where there is a single phone jack and limited phonelines around the house. Power lines, while omnipresent, are very noisy and do not allow for high data rate traffic."

However, he noted, there are many innovative technologies that could promise power lines to become a viable network. "Quite simply, over 70% of devices in the home require a power cord, and it would be ideal to network the appliances through the same power cord," Dhir said. "Meanwhile, Ethernet and fiber require laying out new cables. They do, however, provide faster data rates and superior protocols such as 1394 and USB 2.0 to be transmitted for voice, data, and video support."

3G: The Wild Card?
Once third-generation (3G) wireless networks reach wide deployment, designers may want to consider merging gateways with the cellular network, such that a 3G handset may adapt itself to a "home" or "road" network. This may alleviate the difficulties some consumers have of switching between phones, and could lead to greater telephony integration, especially if protocols like the wireless application protocol (WAP) can be supported.

Embedded Wireless Devices' Christy thinks it's not a bad idea to consider. "We're starting to believe there should be some bridging between the WAN/cellular network and the home. But, the question is, how to bridge them? Can you have a cell phone that would adapt to the home? Once it's in your network it can hook up to your system there, or at work, you can switch automatically to VoIP services, tapping into broadband networks and realizing new services." Flash memory that can automatically load the needed protocols would be a critical part of such a device, Christy said.

"Definitely, protocols like 3G should be supported," Ucentric's Vasilovsky said. "Gateways need to be part of a network that can deliver content and services to consumers anytime, anywhere, seamlessly." Software platforms that enable gateways to use WAP-, WML-, or HTML-enabled cell phones, he said, as well as support for SMS messaging system alerts and caller-ID messages, open up whole new categories of products that interact with dual-purpose cell phones.

The merging of cell phones with home networks makes sense to TI's Riley as well; he is bullish on the possibilities of such confluence. "Consumers will want the same connectivity wherever they are, including their home. And when they are home, they will want to also access their local network." Considerations will need to be made, he said, for transferring information between the home and 3G networks - or the possibility of a cell phone with 802.11 capabilities. But, he added, "There are a lot of technical and service related questions that will need to be answered before this happens."

Duty Now For The Future
So it's clear that standards are in constant flux. How then does a residential gateway designer go about future-proofing? After all, getting gateways deployed in the first place is arguably the most pressing problem in getting the much vaunted services (on which so much depends, economically at least) out to a broader customer base.

This means paying attention to components. Conexant's Kempf says the most practical way to future proof a gateway is to provide it with sufficient flash memory as well a good amount of processor overhead so that firewall upgrades and protocols such as universal plug and play (UPnP) can be implemented as they become available. "It is also important that every gateway be enabled with a HTTP microserver," he said, "so that customers can easily download upgrades and save them in flash without having to use a command line interface."

"A gateway, by definition, is not future-proofed," Ucentric's Vasilevsky said. "These and other non-managed devices can be built with memory enhancements, but the 'future proofing' possibilities are limited to bug-fixes and minor upgrades, not for wholesale additions of functionality."

For managed and network connected devices, Vasilovsky said, designers and providers can tap an application framework that enables rich services to be remotely provisioned and deployed over time. As such, he noted, these managed devices will effectively eliminate stranded capital and let providers leverage the CPE already in the home.

Alcatel's Goffart added, "Firmware upgrading will offer a solution to interoperability improvement, management of traffic prioritization service customization, and firewall security enhancements. We see a lot of evolution in the medium that will be used in home networking that will not be solved with just a software upgrade."

Whatever happens it pays to keep a close eye on the standards. Designers working on gateways are in a sense being asked to do the impossible - predict the future. Keeping systems adaptable with reconfigurable logic, flash memory, and versatile network processor architectures is a good start. But a good ear with which to listen to the market's demand is priceless in this scenario. We're not suggesting you sit in on marketing meetings just yet, but now's the time to pay attention.

About the Author

John Poultney is a freelance technology writer in Northern California, and is the former Executive Editor of Communication Systems Design. He can be reached at jpoult7734@aol.com.

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© 2002 CMP Media LLC.
1/1/02, Issue # 801, page 18.