networkZONE Products for the week of July 26, 2004
Atheros Says…
Hi-Fi Wi-Fi - Atheros Introduces Video Chipset for
Affordable HDTV-Quality Wireless
Integrated support for video/audio controllers and multiple-radio/smart-antenna
technologies enable reliable, low-cost HDTV, DVR and Media Center applications
Atheros Communications, Inc. has introduced the first standards-compliant
WLAN chipset optimized for high-quality multimedia applications. The AR5005VA
chipset implements reliable wireless video and audio connections throughout
the home -- even a Texas-sized home -- by integrating a complete set of
high-performance features. These features range from on-chip interfaces
to multimedia chipsets and quality of service (QoS) to multiple-radio/smart-antenna
technologies such as transmit beamforming and receive combining.
"For the first time, consumers have a low-cost way to eliminate cables between TVs and set-top boxes, DVD players and other video sources," said Craig Barratt, president and chief executive officer of Atheros Communications. "TVs can become portable again, only now they can deliver DVD quality or even HDTV."
By sustaining multiple DVD-quality links (6-8 Mbps each) or a combination of HDTV (19-24 Mbps each) and DVD-quality links throughout homes of up to 6,000 square feet (550 square meters), the AR5005VA chipset provides an easy unplug-and-play experience for consumers. Since the chipset provides enhanced performance using standard 802.11a/b/g technologies and 802.11e quality of service, it also enables TVs to pull multimedia content from personal computers using standard 802.11a/b/g wireless networking. Users can view and organize PC-based photos and videos, play audio sources such as MP3, Apple AAC, and Sony ATRAC files, and play video files from Windows Media Center devices. The chipset can also eliminate the unsightly signal cables now needed to connect wall-mounted flat-screen TVs.
Integrated Video/Audio Controller Support
Addressing one of the biggest barriers to wireless audio/video acceptance,
Atheros has dramatically reduced this technology's cost. Previous wireless
chipsets and video/audio controllers have each been popular, but the complex
and proprietary nature of integrated designs limited the availability of
wireless multimedia.
The AR5005VA chipset brings wireless multimedia within the reach of virtually any consumer by providing direct support for the video/audio chipsets used in high-definition TV (HDTV), digital TV (DTV), digital video recorders (DVRs), set-top boxes (STBs), and Windows Media Center devices. This high level of integration makes it easy and economical to include wireless support in new and existing consumer electronics products. The Atheros multimedia support includes direct interfaces, as well as MPEG-Transport Stream support, host controller, and direct memory access (DMA) acceleration for chipsets from ALi/T-Square, ATI, ESS, Entropic, NEC, Sigma Designs, VWeb, Zoran, and others.
The AR5005VA even includes a universal infrared (IR) modulator and repeater capability for forwarding the consumer's IR remote-control signals to a source device such as a DVD player or set-top box. This functionality allows consumers to use standard IR remote controls with an AR5005VA-based device to control existing IR-controlled products from across the home.
Glitchless Multimedia
The AR5005VA chipset includes quality-of-service capabilities that ensure
high-quality video and audio delivery while simplifying product designs.
The device supports 802.11e Quality of Service and adds a number of features
demanded by consumer electronics manufacturers. To provide wired-quality
reliability and consistency, for example, the chipset includes hardware
packet jitter control and MPEG packet aggregation.
For additional flexibility, the chipset's integrated MIPS R4000-class processor also supports digital rights management (DRM) technology and MPEG encapsulation into other protocols as specified by the Digital Living Networking Alliance (DLNA). With this capability, system designers can treat the wireless interface as a link that is as simple and secure as a wired connection.
Atheros thus eliminates problems with previous generations of products that often made it difficult and expensive to adapt wired video designs to the physical challenges of a wireless environment. The AR5005VA's quality-of-service capabilities allow product designers to treat the radio link as a wireless 1394 or Firewire connection.
Standard wireless networking with a kick
Because the AR5005VA chipset uses standard WLAN protocols, it implements
networks that interact and coexist seamlessly with other standard 802.11a,
b or g wireless devices, as well as Atheros Super G and Super AG devices.
Super G and Super AG products implement innovative performance-enhancement
features that can triple the available throughput of 802.11g or 11a/g networks.
The AR5005VA also introduces multiple-radio/smart-antenna capabilities, including transmit beamforming and multiple receive combining, with support for up to four antennas. The chipset integrates dual orthogonal frequency division multiplexing (OFDM) baseband processors and radio devices to focus radio frequency (RF) energy toward the intended receiver -- a unique feature for a WLAN device.
The receiver also uses up to four antennas for receive combining to extend range and improve robustness. This technique takes advantage of the significant difference in radio signals available to multiple antennas and uses advanced signal processing to combine the signals and thus improve overall signal strength and quality.
Products using the AR5005VA chipset's transmit beamforming and receive
combining allow consumers to use the wireless interface just as they would
a wired connection. The combined technologies increase the effective signal
by up to ten-fold or approximately 10 dB. Transmit beamforming by itself
provides a gain of approximately 5-7dB even when the other end of the link
is a standard 802.11 device; and receive combining provides approximately
3-5dB gain. These capabilities are fully compatible with legacy WLAN devices.
The AR5005VA is the first of a family of Atheros products to support multiple-radio/smart-antenna,
multiple-input/multiple-output (MIMO) and other anticipated 802.11n technologies.
analogZONE Says . . .
It's often true that the most interesting applications for a technology aren't the ones that it was originally intended for. And the imminent proliferation of Wi-Fi for wireless multimedia distribution is a case in point. Atheros's new multi-radio, multi-media-oriented transceiver is being trotted out to help the company grab a big chunk of market for wireless media distribution products that they predict will rival the sales of wireless data networking equipment within a year or two. The AR5005VA chipset is the first of a family of Atheros products intended to address the specific requirements of equipment dishing out wireless audio and video streams.
Atheros has taken a unique architectural approach that combines their proprietary SuperG high-throughput technology with a dual-radio system to produce a Wi-Fi transceiver with the 60+ Mbit/s of actual TCP traffic capacity that they felt would provide the speed margin and reach needed to support conventional and HDTV video streams for TVs, Media Gateways, PVRs, and DVDs across the distances needed to cover a large (6000 ft2) home. We'll cover the radio section first, but be aware that the chip set also has some other important features not found in other products intended for data-only terminal cards, or even broadband gateways that should make multimedia products easier and less expensive to design.
Their dual receiver architecture uses two AR 5112
a/g radio chips (see block diagram) and two, or four, antennas to implement
a "MIMO-like" scheme that does some elementary beam-forming which
significantly improves its link budget. I say that it's a MIMO-like scheme
because it transmits the same data on both radio channels instead of two
different data streams. Previous chipsets use their earlier extended range
(affectionately branded as "XR") technology to enable reception
below the normal noise floor (down to -105 dB). This new technique actually
delivers extra effective signal strength towards the receiver in question.
While both technologies deliver longer, more robust links, the intent of
using beam forming is to deliver a stronger signal that keeps the throughput
high enough, and the bit error rate low enough to support glitch-free multimedia.
Atheros implements its beam forming by working at both the RF land baseband level. First, the baseband section uses 802.11's long training symbol sequence to measure the RSSI on each of the channel's 52 bins and develop both receive (like all companies) and transmit (unique to Atheros) channel estimation parameters for every OFDM tone in use. While not as detailed an analysis as the FFT spectral data that Engim's multi-channel radio can provide, it's more than enough to infer which antenna has the "best" signal path for a given tone.
This channel response data for each OFDM tone is converted to a weighted average value and inverted by the baseband to control the relative amplitudes and phasing of the two transmitters. This transmit power profile allows for precise adjustment of the transmit signal strength between the two radios on a per-carrier basis.
Atheros claims that their beam steering technology adds between 3 and 5 dB to a link budget with Atheros silicon a base station, and 5 - 7 dB (and more under ideal conditions) when both ends of the link are Atheros-equipped. This allows them to offer nearly double the range normally available for A/V channels carrying up to 30 Mbit/s worth of usable data (even with the 30% - 40% channel overhead is factored out). They say that you can expect near-full-rate connections up to 100 ft in homes with standard timber construction, distances that could cover up to 6000 ft2 of floor space (with proper placement of the base station). Of course, your mileage may vary...
But raw throughput isn't enough for multimedia since latency variations, packet loss, and other glitches can ruin the quality of even the fastest link. As the press release above explains, the AR5005VA addresses design issues well beyond the radio with support of the 802.11e QoS standard. But Atheros contends that even 802.11e is insufficient to deliver solid video unless all units in the network are 802.11e-equipped, and there are no significant interferers in the area. To cope with realworld environments where interference is the norm, they've added their own proprietary embedded time stamp the packets within the transmitted frames. This enables reliable reassembly of video frames with minimal packet loss.
The AR5005VA also sports dedicated logic for video processing and transport tasks. This includes hardware packet jitter control to eliminate video glitches, MPEG packet aggregation, MPEG encapsulation, and support for digital rights management. Its on-chip security logic also includes support for AES-level encryption. There is also an embedded MIPS R4000 processor which, among other things, can employ 3rd-party software to handle digital rights management (DRM) and content protection functions.
Atheros is one of the only companies to introduce a solution that's purpose-built for multimedia distribution. About the only other competition on the horizon at the moment is Agere's performance-oriented Wi-Fi chipset that boasts data rates as high as 150 Mbit/s in its latest "turboG" mode. Of course the current Agere chip set does not have all the hardware support for streaming video that Atheros does, but they are very committed to this market and I expect to see comparable products from them by the end of the year. And at the risk of sounding like a shill for Engim, I think that they could easily adapt their current multi-channel transceiver to deliver similar or possibly better functionality -- albeit at a somewhat higher BOM cost.
Competition aside, Atheros has done a great job here by integrating many essential features and functions that would be difficult, expensive, or impossible to implement with discrete components. It's also gratifying to see that they have abandoned their earlier obsession with getting every penny out of the BOM cost regardless of its impact on performance. And I can't even complain that it's too expensive at $19 for the entire chip set.
About the only outstanding issue I feel the need to raise is that, in their race to market, Atheros has released a chip that may or may not be able to support the final 802.11n standard -- when, and if, it ever arrives. But this is understandably Atheros' need to establish its dominance in what it perceives to be a vital, and rapidly-emerging market for multimedia-capable Wi-Fi gear. While I often stress the need for using fully-standards-compliant silicon in applications which run within public infrastructures, using Atheros' pre-standards silicon for dedicated home networking is acceptable -- although it may force consumers to stick to a single brand of networking equipment, and adds the risk of early obsolescence.
The AR5005VA chipset is sampling in both two- and four-antenna configurations with the latter costing under $19 in 10-k piece lots. Production will be in Fall 2004.
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