DALLAS -- Drawing on its modem, digital signal processing and voice-over-packet software expertise, Texas Instruments Inc. here this week introduced a complete voice-capable cable modem solution that overcomes the limitations of packet-based voice transmission. The company said its hardware and software will allow multi-service operators (MSOs) to get up and running with bundled services such as primary-line telephony for residential gateways, secondary-line telephony for voice-enabled cable modems and multiline offerings for multidwelling units.
"You must have a complete system solution," said Rod Trautman, worldwide marketing manager at TI (Houston), pointing out that the cable industry's research arm, CableLabs, "is testing a system -- not just a chip, not just hardware." Saying that competitors are offering "only pieces," Trautman said TI has put together "the leading modem technology, from our Libit acquisition, plus TI's own lowest-power DSP technology combined with Telogy's voice-over-packet software," which he called "the de facto industry standard."
The result is a three-part solution that consists of the TNETC4042 media-access control and physical-layer chip; the TNET4320 cable-modem processor, which is based on two of TI's low-power C54X DSPs running at 133 MHz; and Telogy's Golden Gateway packet voice software.
TI's announcement came just days after the Federal Communications Commission released figures on high-speed Internet access in the United States. Information filed by qualifying providers, which includes data as of June 30, indicates that the number of high-speed lines linking homes and small businesses to the Internet rose by 57 % during the first half of 2000. They now total 4.3 million lines (or wireless channels), up from 2.8 million at the end of 1999. About 2.8 million of these lines provided speeds of better than 200 kbits/second in both directions, compared with 2 million at the end of last year.
Of these services, asymmetric digital subscriber lines increased by 157%, to almost 1 million lines, against about 370,000 lines by the end of 1999. In comparison, lines over cable systems grew 59% to about 2.2 million, compared with 1.4 million last year.
It is the cable-modem market, which has mushroomed since June, that TI is aiming for.
The TNETC4042 chip is based on the company's Docsis 1.1-certified 4040, which TI touts as the lowest-power MAC/PHY on the market to comply with the data over cable system interface specification.
"This is essential for primary-line operation," said Trautman, referring to residential-gateway applications where the main line must be powered. "Devices for this application mounted on the side of the house must also be industrial strength to withstand the temperature extremes." He said the new TI solution "is fully suited to this."
The second device, and the heart of the system, is the TNET4320 cable modem processor. Each of the pair of low-power C54X DSPs on which it is based come with 96 kwords of local memory and 128 kwords of shared memory. The DSPs are complemented by a 125-MHz MIPS Technologies 4Kc (Jade) CPU with 16 kbits of instruction and 16 kbits of data cache, along with 4 kbytes of on-chip RAM and ROM.
As the brains of the system, the 4320 includes an eight-port USB controller, two 10/100 Ethernet MediaIndependent Interfaces, two UARTs and a general-purpose I/O bus. The device also comes with a PCI master/slave interface, which can be used for wireless 802.11b content distribution.
Another, lower-power version of the chip, the 4310, has all the features of the 4320 except it integrates only one C54X DSP and 128 kwords of local RAM.
Packet telephony proliferation
"While there are multiple ways to distribute content, we believe the final solution will be wireless,"
Trautman said, "either wireless LAN or Bluetooth, depending on whether the distribution is point-to-point
or a network." With a cable modem in the house able to carry voice, and with Bluetooth as the distribution channel, Trautman reasoned that wireless packet-based telephony via cable modem will proliferate. "With one-half the cell phones now putting Bluetooth inside, I can have a BT handset in the house or use my existing cell phone as a local phone line in the house," he said. "Those are the kinds of things we think will win out."
The third leg of TI's cable modem solution is Telogy's voice-over-packet software. "The primary standards for voice are the coding specification and the Media Gateway Control Protocol signaling specification," said Debbie Greenstreet, senior product manager for Telogy's cable modem division. "That's software Telogy has had for well over a year now, and we have been working with CableLabs on integrating those solutions and getting fundamental call capability set up."
MGCP addresses a lot of what happens in terms of the voice-processing features in the DSP. It essentially determines how the cable modem interfaces to the call agent to set up and provision calls.
One key area on which Telogy focused to make the Golden Gateway software work for deployable voice-over-cable was quality of service (QoS). "We had to make sure voice calls have priority and are of the required quality," said Greenstreet. One of the hooks in the Docsis spec that provides for QoS is the unsolicited-grant service, which grants voice calls priority on the cable system. Other hooks include provisions for dynamic QoS and security.
"Security is key," said Greenstreet, "as you want to make sure firstly that voice calls are secure and that no one's listening to the call, and secondly that no one can go in and steal services, so MSOs multiservice operators feel comfortable."
To enhance its security offering, TI recently aligned with RSA Security Inc. of Bedford, Mass., to incorporate that company's BSafe Cert-C software to enhance TI's reference designs for cable modem manufacturers. BSafe provides an end-to-end encryption, decryption and digital certificate capabilities between cable modem termination systems and customer premises equipment.
The company has also included a management information base that makes it possible to manage the setup by collecting all the statistics, providing all the information and allowing configuration alterations.
Voice over cable "is a lot more than just the codecs, the DSP processing and the signaling," Greenstreet said.
Silicon for the TI cable modem solution will sample by year's end, with production due by the second quarter of 2001.