Startup Inprocomm hardwires 802.11b baseband functions

Startup hardwires 802.11b baseband functions
By Robert Keenan, CommsDesign.com
December 2, 2002 (2:28 p.m. EST)
URL: http://www.eetimes.com/story/OEG20021202S0063

ROCHESTER, N.Y. - Leaving an ARM processor on the shelf, startup Inprocomm is coming out of stealth mode this week with a baseband/media-access control (MAC) IC that sees many of the IEEE 802.11b wireless LAN functions implemented in hardware. By eliminating dedicated processors-such as an ARM-the chip's architecture is intended to lower the size, cost and power consumption of WLAN transceivers.

Inprocomm is the component arm of Integrated Programmable Communications Inc., a Taiwanese developer of intellectual property (IP) for WLAN and other wireless applications. Founded in 2000, Integrated Programmable Communications started by building IP for Bluetooth, said Craig Conkling, director of marketing and product development at Inprocomm. However, the company quickly saw interest in WLAN growing and focused its algorithm, digital signal processor and analog development activities on 802.11b solutions.

Now Integrated Programmable Communications is taking the next step in its quest to crack the competitive WLAN market. By launching Inprocomm, the former IP-only developer has created a vehicle for building and marketing ICs for the sector.

The IPC2120 is the first chip to hit the market under the Inprocomm name. This IC handles the baseband and MAC tasks in 802.11b systems. At the same time, the chip delivers security functions, including 64- and 128-bit wired-equivalent privacy, Temporal Key Integrity Protocol and Advanced Encryption Standard (AES).

Facing the challenge of gaining market attention in an already overcrowded 802.11b sector, Inprocomm is banking on its architectural approach to overcome the hurdle.

Unlike most baseband/MAC developers, which use an ARM processor on-chip, Inprocomm is taking a totally hardwired approach to its chip architecture. In the Inprocomm architecture, data enters the chip and gets processed by the modem. It is then handed off to a protocol access unit (PAU), which controls all of the protocols on-chip. Data is then sent to first in, first-outs (FIFOs), where it is buffered and prepped to go out over either a mini-PCI or CardBus interface. "We have enough buffering on-chip to handle the full packet string," Conkling said.

The big difference between ARM-enabled processors and the Inprocomm solution lies in the handling of firmware. Most WLAN chip vendors have built their solution around the ARM processor so that firmware tasks can be handled by the on-chip ARM. However, by leaving the ARM off, Inprocomm must shift its handling of firmware off-chip as well. Specifically, Inprocomm turns to the host CPU to handle firmware functions such as the base 802.11b protocol. "The Mips required to handle the firmware are insignificant on many processor architectures these days," Conkling said.

Systems featuring a StrongARM, Xscale or Pentium-class processor should have no issue handling the firmware duties, Conkling said. In other portables, the firmware adds "a little extra work," but doesn't burden the proce ssor, he said.

Smaller die size

Size could be where the hardwired approach shines. The IPC2120 will come in a 128-pin package. As Conkling noted, most WLAN processors are delivered in 196-, 208- or 256-ball grid arrays. "Our hardwired approach shrinks the die considerably, maybe by 40 percent or more."

The hardwired approach also reduces power consumption. Through its architecture, Inprocomm could develop a smart power scheme inside the IPC2120. As data streams into the chip, the modem section is powered up to run at 3.3 volts. Then, as data is passed through the chip, the PAU is powered up at 1.8 V and the modem section begins to ramp down. As data is passed along, the buffers/interfaces are then powered up while the PAU begins to ramp down. "We don't have to keep the entire chip powered up all the time," Conkling said.

Overall, the Inprocomm chip draws 50-mA current on the transmit side in worst-case conditions, and 135- to 140-mA current in receive mode, worst case. "That's bet ter than most," Conkling said.

Inprocomm will likely face tough questions about its hardwired security features, as well as its approach to firmware. With the IEEE 802.11i specification still in development, some would argue that hardwiring security features is a risky venture in the 802.11b space.

The biggest questions, of course, surround support for AES, which is one of the big additions in the 802.11i spec. Conkling maintained that the AES spec under development is pretty stable at this point. "If there are any changes, we expect them to be minor things that can be handled in software," he said.

Developed at foundry Taiwan Semiconductor Manufacturing Co. Ltd., the IPC2120 will start sampling on Dec. 15. Full production is slated for January 2003. Conkling expects the total bill of materials for a chip set using the IPC2120 to be under $18.