SAN JOSE ( ChipWire)-- With introductions from this week's Voice on the Net show, developers now
have two new options for offering embedded packet voice support in small form factors.
Mitel Semiconductor is challenging DSP giants like Lucent Technologies and Texas Instruments with a full voice-over-Internet Protocol (VoIP) chip set that supports the H.323, Media Gateway Control Protocol and Session Initiation Protocol client protocols. And Tellabs Inc.'s Coherent
Communications OEM operations group has designed a multichip voice-quality engine to provide
VoIP support with echo cancellation and encryption in a PCI mezzanine card (PMC) format.
The Mitel 921XX set is the result of a focused development effort that combined design teams from
Mitel Canada and the former GEC Plessey. At the heart of the chip set is the MT92102 phone
controller, with an ARM7 RISC CPU, an Oak DSP core and a full Ethernet bridge. Product manager
Trefor Davies said the part is a fifth-generation combination RISC/DSP controller. The earlier
devices targeted mobile phone markets.
In June, Mitel design groups examined the status of packet voice chip set efforts at Lucent, TI and 8x8 (now Netergy Networks Inc.) and determined that the wireless phone controller could be adopted as the base for a VoIP chip set. The team set this week's Voice on the Net show in San Jose as a deadline for sampling, and beat the deadline by several weeks.
On the software side, Mitel developed an echo-reduction algorithm, called Trueplex, to track
changes in echo paths caused by packet loss and to provide fast reconvergence times for better
end-to-end voice quality in packet phones. Trueplex offers true full-duplex operation, without
reversion to half-duplex at times of network congestion.
The controller supports on-chip acceleration of packet encryption using Triple DES or IPsec
algorithms. The Ethernet bridge on the controller chip supports 802.1p tagging for packet
prioritization to implement quality-of-service parameters. As the Internet Engineering Task Force finishes its Differentiated Services (DiffServ) standard, the controller will allow establishment of a DiffServ code point.
Surrounding Mitel's main controller are the MT92303 codec and the MT933 physical-layer
Ethernet transceiver. The dual-channel codec includes the hands-free features used in mobile
telephony and adds drivers for office environments, such as speaker-phone operation.
The MT933 is a CMOS transceiver developed as part of Plessey's LAN program. It supports
auto-negotiation for 10 and 100 Base T networks.
Tellabs' OEM operations group in Ashburn, Va., the former Coherent Communications, is applying its expertise in wireless echo cancellation to wireline IP for the first time. David Powell, vice president and general manager of the network-enhancing technologies solutions group, called the
IEC-160MCIP engine "a voice quality enhancement product" as well as an echo cancellation
Tellabs is willing to concede the consumer IP phone market to TI/Telogy, 8 x 8, and other chip
vendors with algorithm-based echo cancellation. The Tellabs hardwired design is optimized for
packing as many channels into media gateway and softswitch systems as possible. The mezzanine
card being introduced this week, for example, will support 160 channels of VoIP. Proprietary echo cancellation is implemented in ASICs; standard codec algorithms are added for voice compression. Tellabs implemented jitter buffering in a special logic block called the Packet Playout Unit, which also compensates for packet loss.
The PMC card is a legitimate two-bus translation device, taking in pulse code modulated (PCM)
voice from an H.110 bus and sending out IP packets across a standard PCI bus. The PCM interface
supports both A-law and Mu-law encoding.
The 5.9-inch x 2.9-inch card also integrates such standard telephony features as fax relay; DTMF
tone generation and detection; and comprehensive self-test logic, including non-interfering testing
for data RAM and convolution RAM.
Like Tellabs' earlier products for wireless environments, the new IEC-160MCIP supports voice
activity detection, in which periods of silence are sensed in the upcoming TDM signal, and all
voice packets are suppressed. At the same time, the system provides some limited noise in the
channel so users perceive they are still connected.
All current Tellabs/Coherent OEM subsystem products will be upgraded with chips from the new
160MCIP engine, which now will become the standard Tellabs echo cancellation technology.
Tellabs will consider chip licensing case by case, though Powell said that card-level
implementations, such as PMC cards, seem to be a preferred form factor for many gateway