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DSPs: Key to broadband's future

Posted: 01 Mar 2001 ?? ?Print Version ?Bookmark and Share

Keywords:dsp? broadband? adsl? irg? residential gateway?

Multimedia is not a new topic or idea, but it is one that is being renewed by broadband technology such as digital subscriber line (DSL) and cable. Over the next several years, we will witness a proliferation of non-PC, broadband-ready appliances around the home that will take advantage of the high-speed bandwidth from DSL or cable to enhance the multimedia experience. A projection by Strategy Analytics predicts that by 2005 the market for non-PC online appliances will grow to $11.6 billion. Many of these appliances will have less to do with computing and more to do with entertainment, communication, home automation and other new applications. And at the center of many of these devices will be a DSP.

While DSP technology is integral to the new broadband appliances we will be seeing around the home and small office, it is also playing a central role in the broadband access technologies such as DSL that will deliver high bandwidth to these appliances. By using a programmable DSP as the data processor of the ADSL modem, support for new standards or new software are easily downloaded to upgrade the modem's code. A closer look at DSL shows just how important the programmable nature of a DSP becomes to support the standards and interoperability requirements of the ADSL industry.

Splitting the line

Using the existing telephone local-loop copper, DSL enables high-speed network access over existing copper twisted-pair wiring. By splitting the phone line into two frequency ranges, ADSL effectively enables both voice and data transport over the same line?0 to 4kHz for voice or POTS services and 26kHz to 1.1MHz for data services.

The many different standards for ADSL from organizations such as the American National Standard Institute (ANSI) and the International Telecommunications Union (ITU) aim to make DSL interoperable to ensure that all customer premises modems, no matter whose technology is in them, are able to connect to other companies' technology on the central-office side. This does not insure interoperability, but through testing efforts from industry groups such as the DSL Forum and service providers mandating that DSL technology be certified to work in their networks, DSL is quickly on its way to becoming an uncoupled market with the ability to support multimedia networking applications.

One could certainly paint an idyllic picture of the future with new broadband-ready appliances dotting the residential landscape and large broadband pipes feeding the home with more bandwidth than it has ever had before. But there is a catch. How this huge bandwidth will be distributed inside the home will become a challenge. The solution will come about as we begin to perceive broadband communications as another foundational element of the home much like the structural foundation, plumbing or electrical wiring. Simply connecting each Internet-ready device to a broadband pipe will not make the most efficient or cohesive use of the appliances themselves or the bandwidth in the pipe.

Most forward-thinking OEMs and service providers already have some sort of residential gateway appliance on the drawing board or, at the very least, on their radar screen. These devices certainly will vary in capability, functionality and complexity but will manage and deliver the high-speed bandwidth to multimedia appliances, including PCs that will share access to the broadband pipe. In fact, the residential gateway will progress through several distinct generations in the years ahead.

The road to the intelligent residential gateway (IRG) begins with the ADSL PHY that handles Layer 1 data processing. This model is what is commonly deployed in today's PCI and USB external DSL modems to bring bandwidth to one PC. Adding more functionality to the ADSL PHY model, the ADSL router (RT) or network terminal (NT) is capable of simple data-only routing and bridging functions, such as managing the physical layer and distributing the data to several PCs or appliances--usually through Ethernet connections. Both ADSL PHYs and RT or NT modems are currently being deployed for DSL access worldwide.

The next step toward multimedia applications is the combination of voice and data processing. Just beginning to be deployed in the market, integrated access devices (iads) perform all of the functions of the ADSL RT/NT as well as voice services like voip and voice-over-ATM. In addition, IADs will have greater flexibility to accommodate different physical-layer interfaces for new networks or new network configurations in the future.

Eventually, the intelligent residential gateway (IRG) will emerge, adding significant new capabilities to those of the IAD. With coprocessing and the ability to add new PHYs, the IRG will manage new services and applications beyond data and voice. With third-party multimedia applications and services such as interactive gaming, video-on-demand and home entertainment, service providers will be able to offer more services to the home. Recently, electronic gaming consoles have been introduced where broadband, entertainment and multimedia are all integrated into one piece of equipment.

With the IRG comes a need for high-speed, real-time processing for communications functions. A gateway with a DSP efficiently and cost-effectively performs the real-time multimedia processing inherent to broadband communications since DSPs are optimized to handle communication functions such as voice and data. Additionally, this gateway extends the benefits of the many DSPs that have already proliferated around homes and offices in appliances and devices such as cellphones, digital speakers and Internet audio players.

As DSP-based routers or gateways begin to take on the role of multimedia traffic cop, a real concern arises over how this technology will cope with the inevitable changes of the future. What happens when the next great consumer entertainment appliance is invented and requires a totally new data format or protocol? Will this mean that a new gateway device will have to be installed in homes around the world?

Unlimited possibilities

An IRG with a programmable DSP is a simple download away from accommodating as many new applications as there are imaginative designers developing them. From the perspective of those service providers that plan to spend $200 billion over the next four years, programmability is the ultimate in future-proofing their networks. Instead of dispatching a truck to implement new applications, a provider can download a code into a particular home's gateway appliance to deploy new services quickly and cost-effectively.

There is no doubt that broadband is here to stay. Whether it is DSL, cable or fixed wireless, the high-speed pipe into the home will soon become the gateway to entertainment, information, home-automation and more. The question is, will this home network be wired or wireless? Wired has a head start in the market, but with technologies such as IEEE 802.11b and Bluetooth quickly being adopted, one thing is for sure?the broadband revolution is just beginning and multimedia networking will become more robust in the years to come.

? Ji Park

DSL Marketing Manager, Broadband Access Group

Texas Instruments Inc.

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