Fine tuning 802.11n for 'visual networking'

Consumer Electronics Show hears that 802.11n isn't good enough

Beyond basic networking

Network users in homes, home offices and small businesses are moving beyond basic wireless networking, says Phillip Pyo, product marketing director for California-based Netgear. More than email and web surfing, users are focusing on advanced applications, such as high-definition video, on a variety of non-PC devices, including network attached storage boxes, Xboxes and other gaming consoles, and media servers. "All this requires a much more resilient, real-time, high-throughput wireless LAN," Pyo says.

"The wi-fi business has been very PC-centric," says Michael Hurlston, vice president and general manager of Broadcom's home and wireless networking business unit. "We're moving the wi-fi market into consumer electronics, such as set-top boxes and HDTV, and into portable CE devices such as handheld game consoles and smart phones."

The 11n chip makers are racing to make such a network with such devices possible. Broadcom used CES to unveil a single 11n chip,called Intensi-fi, in new 65-nanometer process technology, that can transmit simultaneously on both the 2.4GHz and 5GHz bands, but is highly efficient in power use and dramatically smaller than the previous chipset.

For many of these applications, 11n is attractive not simply because of its raw data rates of 150MB/sec to 350MB/sec, but also because of its consistent, higher throughput at greater distances, Hurlston says.

"Even 802.11g can do high definition [video] streaming," he says. "But it can't do consistent streaming at range. Our goal is to provide 10MB/sec at every point in the [entire] house."

The real 11n differences

Hurlston says the differences in 11n won't be in "speeds and feeds" but in how well it supports emerging applications.

To that end, Broadcom features dynamic power control, to selectively drop radio power levels to clients who are near, so that power can be boosted for those further away. It also offers new bandwidth-management features that shift the amount of bandwidth among the connected clients to meet different application needs. And the company says its 11n reference design was the first certified by the FCC for dynamic frequency selection, a technique for sidestepping military or weather systems. The practical result is that it frees up an additional 15 channels for transmissions.

Rival Atheros Communications is also working on "tailoring the wireless LAN for this [new] kind of traffic — other than data," says Todd Antes, vice president of marketing. One way is to make 11n, in effect, more aware of the broadband WAN connection and prioritize the incoming traffic accordingly.

At CES, Atheros simulated an admittedly generous 6MB/sec internet connection to an 11n dual-band access point with Atheros chips. Over that link came a BitTorrent session and, from a server, a movie clip in standard definition video, essentially simulating a 5MB/sec IPTV session. The access point sent both streams to a notebook PC. A utility on the PC showed the bandwidth allocation that an Atheros algorithm was making, having sensed the simulated, incoming service provider pipe and prioritised the two streams, reserving about 85% of the wireless bandwidth for the movie.

A monitor showed the different, but consistent, bandwidth utilisation of the two sessions, and the notebook's screen showed a perfect display of the movie. When the algorithm was shut off, almost at once the BitTorrent utilisation spiked sharply, and inconsistently, and the movie's image began breaking up.

It's not just the chip

But fine-tuning 11n involves more than the wi-i silicon.

"It's not just the chip," says Michael Tennefos, head of marketing for WLAN vendor Aruba Networks. "It's things like the actual channel mapping, and the dynamic power adjustments [to the radios]." The 11n products will be phased in gradually to most WLANs, he says, creating hybrid nets with a mix of 11n, 11g and 11a access points and clients. "In those cases, how do you assign channels and manage power levels to avoid interference? It's quite an engineering challenge."

Vendors have come out with a broad range of gear in response. Netgear's newest 11n access points and routers, announced at CES, feature multi-antenna arrays now layered on the printed circuit board. These "metamaterial" antennas can be dedicated to either the 2.4GHz or 5GHz bands, and to separate sectors of coverage. Software selects the optimal signals and can change that selection if the radio frequency environment changes.

Indeed, changes are more likely as the environment becomes more complex even in the relatively uncrowded 5GHz band. Some of the wireless high-definition TV demonstrations at CES this year used a 5GHz 11n link. Others, such as Westinghouse Digital's new high-definition LCD TV, use ultra wideband wireless silicon, in this case from PulseLink, and SiBeam announced the first 60GHz chipset that implements the relatively new Wireless-HD standard.

In most enterprises, video has been a niche application — a closed circuit TV link that lets the CEO "talk" to employees nationwide, or a stand-alone videoconferencing system. That seems likely to change, and dramatically, in part due to YouTube and social networking sites like FaceBook that have created a new awareness of video as a communications medium

Perhaps as 11n spreads both within the home and the workspace, WLANs will be designed and optimised for streaming media, especially video. In which case network professionals will be looking much more closely at how prospective suppliers are fine-tuning 11n with that end in mind.

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Tags 802.11nCESNetworking & Telecomms IDvisual networking

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