networkZONE Products for the week of March 17, 2003
Agere Systems Says…
Practical Idealism - Agere's Dual-Band 802.11a/b/g
Solution Aims For High Performance, Claims Industry's Lowest Bill Of Materials
Agere Systems has introduced the industry's most integrated multimode
wireless local area networking (LAN) solution aimed at protecting network
investments by enabling seamless connectivity to 802.11a, b, and soon-to-be
deployed 802.11g networks. The multimode chip set, which includes a single-chip,
dual-band radio frequency (RF) transceiver, delivers the industry's lowest
bill of materials with half the number of components of competitors' products.
In addition, the chip set's die-size is a fraction of competitors' 802.11b
designs.
Agere will demonstrate the new dual-band RF transceiver, which will be part of its next-generation WaveLAN portfolio, during the CeBIT 2003 Show in Hannover, Germany, March 12-19. With the ability to operate in both the 5 GHz and 2.4 GHz frequency bands, the RF chip supports IEEE 802.11a, 802.11b and the draft standard for 802.11g. This solution delivers superior performance by exceeding all industry standards for range, sensitivity, transmission and robustness.
The radio is coupled with a multimode media access controller (MAC), a multimode baseband processor and a dual-band power amplifier to form a fully interoperable, single platform for both 802.11a/b/g and 802.11g wireless LAN solutions. Agere's complete multimode solution includes evaluation boards, reference designs, firmware and software drivers, certification utilities, manufacturing test software and full customer support.
The solution, which is capable of achieving data transmission speeds of up to 54 Mbits/s, enables manufacturers of networking, computing and multimedia equipment to address the growing demand for high data rate wireless LAN systems. Agere expects to deliver silicon samples of its multimode solution in the second quarter of 2003.
Solution Enables Seamless Connectivity
"Through our integrated, low-cost solution, we are collapsing the cost barrier to widespread adoption of multimode 802.11 technology and truly seamless wireless connectivity," said Stan Swearingen, vice president of computing connectivity at Agere. "We have timed the introduction of our solution to align with the anticipated market ramp for standards-compliant multimode products that are interoperable with the millions of systems already deployed."
Agere's WaveLAN multimode solution was developed as a result of a joint development agreement with Infineon Technologies, AG. In October of 2002, Agere and Infineon agreed to co-develop, supply and support 802.11 multimode reference designs that include all of the components required by network equipment, consumer electronics and PC manufacturers to offer end products with wireless networking capabilities. Each company is independently marketing its next-generation wireless LAN products. Agere and Infineon will offer the industry's first dual-source model, which gives equipment manufacturers greater flexibility to meet accelerating market demand.
"Our multimode solution comes just five months after the formation of the Infineon alliance and draws on Agere's extensive patent portfolio, as well as our more than 15 years of experience in the development of 802.11 technology," Swearingen added.
Agere, with a 30 percent share of the Wi-Fi chip set market *, is a leading provider of wireless LAN solutions for Original Equipment Manufacturers (OEM) and Original Design Manufacturers (ODM). Its WaveLAN, Wi-Fi-compliant chips, PC cards and modules have been incorporated into the current products manufactured by virtually all of the top PC makers. Agere also continues to be at the forefront of standards development and deployment.
According to IDC, an industry analyst firm, the total market for wireless LAN chips is expected to grow at a 30 percent compound annual growth rate, from $331 million in 2001 to $1.2 billion by 2006. Forecasts indicate 802.11b technology will dominate the market through the remainder of this year, with the demand for multimode solutions rapidly increasing in 2004, once the industry's 802.11g interoperability testing program is finalized.
Much like the cellular industry, which has adopted multimode technology to enable broad network roaming, the wireless LAN industry rapidly is moving towards multimode technology to ensure interoperability and seamless connectivity in the home, office and public hotspots. Multimode solutions deliver the best user experience and performance because they are able to dynamically select transmission modes depending on the network and user environment. Supporting all of the standards for 802.11, Agere's WaveLAN multimode solutions are designed to ensure reliable data transmissions for the widest range of applications whether it is accessing e-mail, downloading large files from the Internet or real-time, multimedia streaming. Multimode products will allow users to connect seamlessly to all 802.11 networks using a single PC card or embedded-client solution.
Unique Chip Set Architecture Drives Performance
Agere uses a multi-faceted approach to deliver a multimode 802.11 chip set with the flexibility to address a wide variety of applications including enterprise networking, home applications and multimedia entertainment. Agere's 802.11 solutions separate the MAC from the baseband and RF chips to provide additional flexibility for systems manufacturers. Unlike all-CMOS implementations, Agere's multimode solution combines advanced BiCMOS, CMOS and SiGe technologies to create a highly integrated, low-cost solution that delivers designs that are optimized for cost and performance.
The WaveLAN RF transceiver (WL54040) is designed in 0.25-micron BiCMOS technology. It is capable of automatically switching between low-intermediate frequency conversion (Low-IF) for OFDM and direct-down conversion for CCK modulation, enabling the device to achieve optimal throughput for all of the 802.11 standards. Specifically, Low-IF conversion guards against dynamic range degradation, an inherent limitation of direct-down OFDM architectures, to provide improved system performance.
Agere's WaveLAN Multimode MAC (WL60040) is fabricated in a 0.2-micron CMOS technology and provides the access controller and data management functions for the chip set. Based on Agere's previous generation MACs, which are the most widely deployed in the industry, the WaveLAN Multimode MAC is compliant to the 802.11a, b and draft-g and h standards, while also supporting the draft 802.11i and e standards for security and quality of service.
Hardware-based AES encryption, combined with software support for WPA (Wi-Fi Protected Access), provides the strongest combination of security enhancements available in the industry. In addition, the multimode MAC delivers added flexibility with a broad range of interfaces for PC, consumer electronics and networking applications including Cardbus, MiniPCI, PC Card, PCI, Compact Flash and USB.
The WaveLAN Multimode Baseband Processor (WL64040), which is developed
in 0.13 micron advanced CMOS technology, contains the complete signal processing
functionality for both OFDM and CCK modulation. It also supports Agere's
patented antenna diversity implementation, which provides enhanced data
throughput and improved signal coverage. The baseband uses a 1.5V internal
power supply to dramatically reduce the power dissipation of high-speed
OFDM signal processing, significantly improving battery life. In addition,
the baseband uses a novel method of iterative channel estimation to digitally
enhance the tolerance of weak radio signals, ensuring reliable connections.
The WL64040 baseband supports a digital interface to the WL60040 MAC, enabling
system integration of the MAC with a simple interface to a single-chip radio
module. The WaveLAN WL54240 SiGe-based, dual-band power amplifier includes
analog power control for the 2.4 and 5 GHz frequency bands and an on-chip
power detector.
analogZONE Says . . .
If it were not for its extensive work on pioneering 802.11 products, I'd say that Agere had come too late to the party with its dual-band WiFi chip set. But, given the experience they have in the area (before selling off their original WaveLAN products to Proxim), and the good relationships developed with many leading equipment manufacturers, I'd say they had a fighting chance at succeeding. This of course, is provided their chip set delivers on the promises it makes.
What they seem to have put together is a performance-oriented chip set, designed with an eye to keeping the "solution cost" as low as feasible. Power is the third priority in this first-pass chip set, but only suffers slightly with power consumption comparable to almost any of today's 802.11b-only products. I heartily approve of this strategy since so many of today's chip sets have been aggressively biased towards shaving dimes and quarters off a BOM with performance running a poor second. If WiFi is to have a future, today's products cannot compromise on range, speed, or performance under difficult conditions. As we'll see later, Agere has found ways to keep its BOM costs low as well, making this a good candidate to survive the shakeout that I expect will rip through the 802.11 sector within the next 6-12 months.
Getting back to the issue of power consumption, Agere hemmed and hawed about specific numbers, but said it was comparable to most "b-only" products on the market today (probably around 100 mA in receive and 150-200 mA in transmit.) They indicated that they will address power consumption aggressively on a second spin when the chip set is integrated further.
While the four-chip dual-band transceiver's design is somewhat aggressive in a few areas, the engineers have not been drinking from the all-CMOS Kool-Aid bowl, and segmented the chip set's functions rationally between CMOS, BiCMOS, and SiGe. This is evident in how Agere kept the PA and antenna switch in separate chips. While it adds a bit to component count, this approach is more likely to avoid many noise, cross-talk, and efficiency issues faced by more aggressively-integrated chip sets.
The WL60040 CMOS MAC chip contains an embedded RISC processor (a proprietary architecture) to handle host communications and some MAC chores, but also contains hardwired logic for implementing the security (8021.i), QoS (802.11e), and other calculation-intensive tasks. The relatively new (draft) features like the 802.11h annex (that will govern dynamic frequency selection and transmit power control) are implemented in software on their proprietary RISC CPU that was originally developed for the original WaveLAN products, and improved for this spin.
Moving up the signal chain, the baseband processor is essentially a configurable (not programmable) DSP that handles mod/demod tasks. It also manages the antenna diversity switch according to an algorithm that uses BER and RSSI to select antenna through the antenna switch.
The dual-band transceiver chip uses a unique receiver that functions in a direct-conversion, zero-IF (ZIF) mode for CCK and switches to a low-IF (LIF) configuration for OFDM operations. I was very curious about why they did this and asked Syed Aon Mujtaba, Director, Wireless Systems Research about it. He explained that a ZIF receiver tends to have better adjacent channel rejection for CCK operation, but less sensitivity, while LIF supplies the linearity and dc offset required for higher sensitivity to the wider bandwidth and more complex modulation scheme. He also explained that the receiver can toggle between ZIF and LIF modes quickly enough to handle two sequential frames with different modulation schemes - even with the short preambles used in ."g" and "a."
Mujtaba was also very proud of the on-chip filters used in the transmit and receive chain. To be precise, the filtering is distributed, with some being done in by active analog filters and the remainder in the digital domain. I believe his claim that breaking up the filtering tasks saves power (the analog filters don't have to be as sharp) and external components while preserving performance (especially adjacent channel interference rejection.)
I also think that the decision to run an external SiGe PA makes sense as it keeps noise outside the radio and allows for high power efficiency. I never thought on-chip PAs made sense over about 10 mW, and have been pretty much proven right - at least for the moment. IceFyre has moved its 5-GHz PA off-chip. And my spies tell me that even Marvell has had to adopt an external PA for its 2.4 GHz-only Libertas transceiver that touted an on-chip PA as a competitive advantage.
So while Agere biased its design towards performance, it would seem that they have not done too badly on cost. While I could not pull a firm price out of them they sincerely believe that it will offer a significant cost advantage over competitors because it uses much less silicon real estate. For example, the entire Agere dual-band solution occupies 40% of the chip real estate of Broadcom's 2.4GHz-only chip set. This is in part because they do high-speed functions in the proper technology, reducing the need got huge guard bands in CMOS. The result is a dual-band radio at 12 mm2 and a single-band radio at 6mm² using 0.25 micron biCMOS. Broadcom uses 26 mm² on a side for their 802.11b-only solution. Agere also says it has a smaller MAC than most - even with extra buffers and security logic required for g/e. One reason they gave me is the DMA-based interface to the controller CPU that eliminated several bulky buffers while upping throughput at the same time.
I am willing to believe that the reduced wafer real-estate more than makes up for any incremental cost premium of a BiCMOs or SiGe process - especially since it will probably improve the yield over a CMOS chip that uses a lot of high-speed analog circuitry. I'm still not convinced however that Agere will be able to cut costs so deeply that their four-chip solution (counting antenna switch) will be significantly cheaper than a two-chip all-CMOS product, but expect they will at least be close enough to let their performance shine through. I expect that some integration will occur on the next spin of the chip set, keeping it competitively priced with most other chip sets worth putting in your next design.
Overall, I think Agere has done a great job here, even if I have a few concerns. One of these is with regard to the front-end design. While conservatively engineered and probably able to perform well on either band, it does not receive both bands simultaneously. This is not an unusual situation (many chip sets work the same way), but it does limit a chip set's utility in access point applications where the equipment should be able to detect activity on one band while operating on another. Client applications don't absolutely require simultaneous band operation, but access points (APs) and gateways do. Like many WiFi chip makers Agere says the solution is to use two radios in a dual-band AP. While this will work, it's a bit less cost-effective than say, Synad, which can support simultaneous operations on both frequencies.
Putting this, and a slightly late start aside, Agere has done a great job in putting together what appears to be a soundly-engineered dual-band radio. I'll be interested to see how it performs, and what its actual pricing will be. The lack of pricing data and a far-out delivery date added a bit to the Vaporware Index Rating, but Agere's long-time experience, and conservative design at least in part compensated for this.
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