Host With the Most
Coresma first out with host-based cable modem
By David Iler
from the June 18, 2001 issue of Broadband Week
In the best of all worlds, from a cable operator's point of view, there would be a cable modem in every new personal computer. That's far from the current reality.
Development of a so-called host-based cable modem, which relies on a computer's central processing unit (CPU) and memory and thus drives down the modem's bill of materials, long has been seen as a giant leap toward cable modem ubiquity.
While silicon giant Intel Corp. had been one of the first chipmakers to set its sights on developing a host-based modem, the first to announce a product surprisingly is Coresma Inc., formerly NetGame Ltd.
Coresma's forte to date has been the development of cable modem and cable modem termination systems (CMTSs) for hotels, apartments and small cable operators.
Yet the much bigger play for Coresma is its host-based modem. Coresma is demonstrating a reference design based upon its Media Access Control chip, which includes four processors running at 80 million instructions per second. Each processor has a co-processor to handle Coresma's software algorithms as well as on-board memory that can be shared between them.
Using its reference design, Coresma has developed a PCI (Peripheral Connection Interface) cable modem card that can be inserted inside any personal computer or set-top box with a PCI interface or slot.
According to Mark Adams, president and CEO of Palo Alto, Calif.-based Coresma, the host-based reference design was achieved through its development of Data Over Cable Service Interface Specification (DOCSIS) 1.1-based software. "We can develop upon anyone's physical layer," he says.
Coresma is using physical layer cable modem technology from Texas Instruments Inc. in its current PCI-based modem, although it has also used physical layer chips from Stanford Telecommunications Inc., now a part of Intel.
Coresma's design relies on its processors to perform management-level tasks, such as modem initialization and wakeup as well as security and network management. A computer's CPU and memory provide the horsepower for the modem's packet-exchange functions and Internet Protocol routing, as well as scheduling and timing on the upstream path. Coresma's algorithms, says Adams, were written to ensure quality and delivery of service by using the host's CPU.
By distributing CPU functions, the modem achieves bill of materials savings of about 20 to 25 percent off current external or internal cable modems, says Adams. Bill of materials costs are further shaved from host-based modems because they share a computer's power supply and don't require an enclosure.
How does the modem's reliance on the computer's CPU impact the computer's performance? Adams says, "We've seen at start-up less than a 5 percent CPU hit in terms of utilization," using a 466 megahertz CPU as a baseline.
Adams says Coresma is in discussions with top semiconductor companies about terms and conditions of a licensing agreement to implement Coresma's technology. Because negotiations are ongoing, Adams couldn't identify the companies but anticipates an announcement shortly.
In the world of cable-based Internet services, however, developing a reference design is merely one step in bringing a product to market. Cable modems, if they are to be officially DOCSIS 1.1-certified, must undergo testing at Cable Television Laboratories Inc. (CableLabs). Intel, according to Taizoon Doctor, general manager for cable network operations, plans to join Coresma in submitting a host-based modem for CableLabs' 19th certification wave, slated to begin late next month, although Intel hasn't announced product plans for a host-based device.
Clearly, host-based modems are top-of-mind at CableLabs, where they are known as CPE Controlled Cable Modems, or CCCMs. "We're very much excited about it," says Rouzbeh Yassini, executive consultant to CableLabs and the main driver behind the DOCSIS program.
CCCMs, Yassini suggests, are a continuation of the industry's quest to "push the envelope on cost" for cable modems. The goal: a $50 retail price for cable modems, compared with the $300 or more they typically retail for now.
Adams admits the $50 price will be difficult to achieve, and he says, "It will take a couple of revisions (of the reference design) to get to that level."
Of course, there's nothing like a little competition to drive down costs, and cable modem chip vendors such as Intel and Texas Instruments also are CCCM contenders.
"The market is very much ready for a product like this," says Doctor. "Richness and ease-of-use of software (for host-based modems) is going to be a key differentiator," he adds, noting that Intel's home networking technologies may be incorporated in a host-based design.
Texas Instruments also is developing host-based modems, based on technology it obtained through its acquisition of Libit Signal Processing in 1999. At that time Libit had been working with Intel at the time to develop a host-based modem.
"A host-based modem is a natural derivative of the existing product today," says Peter Percosan, Texas Instruments' strategic marketing manager for cable products. Texas Instruments' implementation, says Percosan, will focus on the elimination of expensive flash memory from the modem.
TI, says Percosan, also will be focusing on host-based modems for digital set-top boxes, "where we think the better opportunity is."
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